Passive Solar Design Strategies: Guidelines for . Home Building

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Passive Solar Industries Council National Renewable Energy Laboratory Charles Eley Associates With Support From: U.S. Department of Energy Passive Solar Design Strategies: Guidelines for Bom.e Building

Green Bay, Wisconsin

Passive Solar Industries Council National Renewable Energy Laboratory Charles Eley Associates This document was prepared under the sponsorship of the National Renewable Energy Laboratory and produced with funds made available by the United States Department of Energy. Neither the United States Department of Energy. the National Renewable Energy Laboratory. the Passive Solar Industries Council nor any of its member organizations. nor any of their employees. nor any of their contractors. subcontractors. or their employees. makes any warranty. expressed or imp.1ied. or assumes any legal liability or responsibility for the accuracy. completeness or usefulness of any information. apparatus. product or process disclosed. or represents that its use would not infringe privately owned rights. The views and opinions do not necessarily state or reflect those of the United States government. the National Renewable Energy Laboratory. or any agency thereof. This document was prepared with the assistance and participation of representatives from many organizations. but the views and opinions expressed represent general consensus and available information. Unanimous a~~roval by_ all organizations is not implied. PASSIVE SOLAR DESIGN STRATEGIES C;UNII::.N/~

Guidelines

Part One. Introduction ...... 1 1. The Passive Solar Design Strategies Package ...... 2 2. Passive Solar Performance Potential ...... 5

Part Two. Basics of Passive Solar ...... 7 1. Why Passive Solar? More than a Question of Energy ...... 8 2. Key Concepts: Energy Conservation, Suntempering, Passive Solar ...... 9 3. Improving Conservation Performance ...... 10 4. Mechanical Systems ...... 13 5. South-Facing Glass ...... 14 6. Thermal Mass ...... 15 7. Orientation ...... 16 8. Site Planning for Solar Access ...... 17 9. Interior Space Planning ...... 18 10. Putting it Together: The House as a System ...... 18

Part Three. Strategies for Improving Energy Performance in Green Bay, Wisconsin...... '" ...... 21 1. The Example Tables ...... 22 2. Suntempertng ...... : ...... 23 3. Direct Gain ...... ; ...... 24 4. Sunspaces ...... 27 5. Thermal Storage Wall ...... 30 6. Combined Systems ...... 32 7. Natural Cooling Guidelines ...... 32

Worksheets

Blank Worksheets, Data Tables, and Worksheet Instructions ...... 39

Worked Example

DeSCription of the Example Building ...... 47 Completed Worksheets ...... 51 Annotated Worksheet Tables ...... 56 "Anytown", USA ...... 59

Appendix

Glossary of Terms ...... 81 Summary Tables ...... 82 Technical Basis for the Builder Guidelines ...... 84

Green Bay, Wisconsin PASSIVE SOLAR DESIGN STRATEGIES

Acknowledgements J. Douglas Balcomb. NREL and contributed far beyond the call LANL . whose work is the basis of duty. Stephen Szoke. Passive Solar Design Strategies: of the GUidelines; Robert Director of National Accounts. Guidelines for Home Builders McFarland. LANL. for National Concrete Masonry represents over three years of developing and programming AsSOCiation. Chairman of PSIC's effort by a unique group of the calculation procedures; Alex Board of Directors during the organizations and individuals. Lekov. NREL. for assistance in development of these guidelines; The challenge of creating an the analysis; Subrato Chandra James Tann. Brick Institute of effective design tool that could and Philip W. Fairey. FSEC. America. Region 4. Chairman of be customized for the specific whose research has guided the PSIC's Technical Committee needs of builders in cities and natural cooling sections of the during the development of these towns all over the U.S. called for guidelines; the members of the guidelines; and Bion Howard. the talents and experience of NAHB Standing Committee on Chairman of PSIC's Technical specialists in many different Energy, especially Barbara B. Committee during the areas of expertise. Harwood. Donald L. Carr. development of these guidelines. Passive Solar Design James W. Leach and Craig the Alliance to Save Energy all Strategies is based on research Eymann, for the benefit of their gave unstintingly of their time. sponsored by the United States long experience in building their expertise, and their Department of Energy (DOE) energy-efficient homes; at U. S. enthusiasm. Solar Buildings Program. and DOE. Frederick H. Morse. carried out primarily by the Los Former Director of the Office of Alamos National Laboratory Solar Heat Technologies and (LANL). the National Renewable Mary-Margaret Jenior, Program Energy Laboratory (NREL). Manager; Nancy Carlisle and formerly Solar Energy Research Paul Notari at NREL; Helen Institute (SERI). and the Florida English. Executive Director of Solar Energy Center (FSEC). PSIC; Michael Bell, former The National Association of Chairman of PSIC. and Layne Home Builders (NABB) Standing Evans and Elena Marcheso­ Committee on Energy has Moreno. former Executive provided invaluable advice and Directors of PSIC; Arthur W. assistance during the Johnson. for technical development of the Guidelines. assistance in the development of Valuable information was the Guidelines and worksheets; drawn from the 14-country Michael Nicklas. who worked International Energy Agency on the Guidelines from their (lEA), Solar Heating and Cooling early stages and was program. Task VIII on PaSSive instrumental in the success of and Hybrid Solar Low Energy the first pilot workshop in North Buildings (see next page for Carolina; Charles Eley. for his more about the international. help in every aspect of the context of PasSive Solar Design production of the Guidelines Strategies) . package. PSIC expresses particular Altqough all the members of gratitude to the following PSIC. especially the Technical individuals: Committee. contributed to the financial and technical support of the Guidelines. several

Green Bay, Wisconsin Passive Solar Design Strategies GUIDELINES

Passive Solar Industries Council . National Renewable Energy Laboratory Charles Eley Associates With Support From: U.S. Department of Energy Part One: Introduction

1. The Passive Solar Design Strategies Package

2. Passive Solar Performance Potential

Green Bay. Wisconsin 2 GUIDELINES PART ONE: INTRODUCTION

1. The Passive Solar Passive Solar Design BuilderGuide Strategies is a package in four A special builder-friendly Design Strategies basic parts: computer program caller Package • The GuideUnes contain BuilderGuide has been information about passive solar developed to automate the The concepts of passive solar techniques and how they work. calculations involved in filling are simple. but applying it Specific examples of systems out the four worksheets. The effectively requires specific which will save various program operates like a information and attention to the percentages of energy are spreadsheet; the user fills in details of design and provided. values for the building. and the construction. Some passive • The Worksheets offer a computer completes the solar techniques are modest and simple. fill-in-the-blank method calculations. including all table low-cost. and require only small to pre-evaluate the performance lookups. and prints out the changes in a builder's standard of a specific design. answers. The automated practice. At the other end of the • The Worked Example method of using the Worksheets spectrum. some passive solar demonstrates how to complete allows the user to vary input systems can almost eliminate a the worksheets for a typical values. BuilderGuide helps the house's need for purchased residence in Green Bay. user quickly evaluate a wide energy - but probably at a • The section titled Any Town. range of design strategies. relatively high first cost. USA is a step by step In between are a broad range explanation of the passive solar BuilderGuide is aVailable from of energy-conserving passive worksheets for a generic the Passive Solar Industries solar techniques. Whether or example house. Council. Computer data files not they are cost-effective. containing climate data and practical and attractive enough data on component performance to offer a market advantage to for 228 locations within the any individual builder depends United States. The user can on very specific factors such as then adjust for local conditions local costs. climate and market so performance can be evaluated characteristics. virtually anywhere. Passive Solar Design Strategies: Guidelines for Home Builders is written to help give builders the information they need to make these decisions.

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The Guidelines Part Three gives more The Base Case House is a Some principles of passive solar specific advice about techniques reasonably energy-efficient design remain the same in every for suntempering, direct gain house based on a 1987 National climate. An important aspect of systems, thermal storage mass Association of Home Builders good passive solar design is that walls and sunspaces, and for study of housing characteristics, it takes advantage of the natural cooling strategies to for seven different regions. The opportunities at the specific site. help offset air-conditioning Base Case used for Green Bay, So, many fundamental aspects needs. Wisconsin is from the greater of passive solar design will The Example Tables in Part than 7,000 heating degree days depend on the conditions in a Three are also related to region. The house is assumed to small local area, and even on Worksheet numbers, so that you be built over an unheated the features of the building site. can compare them to the basement. because this is Many of the suggestions in this designs you are evaluating. For typical in Wisconsin. section apply specifically to example, the PasSive Solar The examples show how to Green Bay, Wisconsin, but there Sunspace Example Case which achieve 20%. 40% and 60% is also information which will be uses 40% less energy than the energy-use reductions using useful in any climate. Base Case House (page 29) has: three basic strategies: Part One introduces Passive • A Conservation Performance • Added Insulation: Solar DeSign Strategies, and Level of approximately 40,226 Increasing thermal resistance presents the performance Btu/yr-sf, insulation levels without adding potential of several different • An Auxiliary Heat solar features. passive solar systems in the Performance Level of • Suntempertng: Increasing Green Bay climate. Although in apprOximately 31.447 Btu/yr-sf. south-faCing glazing to a practice many factors will affect and maximum of 7% of the house's actual energy performance, this • A Summer Cooling total floor area, without adding information gives a general idea Performance Level of 2,298 thermal mass (energy storage) of how various systems might Btu/yr-sf. beyond what is already in the perform in Green Bay. In this example. the energy framing. standard floor Part Two discusses the basic savings are achieved by coverings and gypsum wall­ concepts of passive solar design increasing insulation about 31 % board and ceiling surfaces. and construction: what the over the Base Case House. Suntempering is combined with advantages of passive solar are, adding a sunspace with south increased levels of thermal how passive solar relates to glazing area equal to 9% of the resistance insulation. other kinds of energy house's floor area. and using a conservation measures, how the ceiling fan to cut some of the air primary passive solar systems conditioning load. work, and what the builder's A Base Case House is most important considerations compared with a series of should be when evaluating and example cases to illustrate using different passive solar exactly how these increased strategies. levels of energy-efficiency might be achieved.

Green Bay, Wisconsin 4 GUIDELINES PART ONE: INTRODUCTION

• Solar Architecture: Using could first calculate the thermal units per square foot three different design performance of the basic house per year (Btu/ sf-yr) - the lower approaches: Direct Gain. you build now. then fill out the heat loss. the better. Sunspace. and Thermal Storage Worksheets for that house with • Worksheet U: Auxiliary Wall. with increased levels of a variety of energy performance Heat Performance Level: thermal resistance insulation. strategies such as increased Determines how much heat has For all strategies. the energy insulation. suntempering and to be supplied (that is. provided savings indicated are based on specific passive solar by the heating system) after the assumption that the energy­ components. taking into account the heat efficient design and construction The Worksheets provide a contributed by passive solar. gUidelines have been followed. way to calculate quickly and This worksheet arrives at a so the houses are properly sited with reasonable accuracy how number estimating the amount and tightly built with high­ well a design is likely to perform of heating energy the house's quality windows and doors. in four key ways: how well it will non-solar heating system has to . The Guidelines section has conserve heat energy; how much provide in Btu/yr-sf. Again. the been kept as brief and the solar features will contribute lower the value. the better. straightforward as possible. but to its total heating energy needs; • Worksheet m: Thermal more detailed information is how comfortable the house will Mass/Comfort: Determines aVailable if needed. References be; and how much the annual whether the house has adequate are indicated in the text. Also cooling load (need for air thermal mass to assure comfort included at the end of this book conditioning) will be. and good thermal performance. are a brief glossary; a summary The Worksheets are Worksheet III calculates the of the Example Tables for Green supported by "look-up" tables number of degrees the Bay. Wisconsin. and the containing pre-calculated temperature inside the house is Technical Basis for the Builder numbers for the local area. likely to vary, or "swing". during GUidelines which explains the Some of the blanks in the a sunny winter day without the background and assumptions Worksheets call for information heating system operating. A behind the Guidelines and about the house - for example. well-designed house should Worksheets. floor area and proj ected area of have a temperature swing of no passive solar glazing. Other more than 13 degrees. and the The Worksheets blanks require a number from less the better. The Worksheets are specifically one of the tables - for example. tailored for Green Bay. from the Solar System Savings Wisconsin. and are a very Fraction table or from the Heat important part of this package Gain Factor table. because they allow you to The Worksheets allow compare different passive solar calculation of the following strategies or combinations of performance indicators: strategies. and the effect that • Worksheet I: Conservation changes will have on the overall Performance Level: Determines performance of the house. how well the house's basic The most effective way to use energy conservation measures the Worksheets is to make (insulation. sealing. caulking. multiple copies before you fill etc.) are working to prevent them out the first time. You can unwanted heat loss or gains. then use the Worksheets to The bottom line of this calculate several different Worksheet is a number designs. For instance. you measuring heat loss in British

Green Bay, Wisconsin • Worksheet IV: Summer 2. Passive Solar system has 145 sf.The energy Cooling Performance Level: savings presented in this Indicates how much air Performance example assume that all the conditioning the house will need Potential systems are deSigned and built in the summer (It is not, according to the suggestions in however, intended for use in The energy performance of these Guidelines. It's also sizing equipment, but as an passive solar strategies varies important to remember that the indication of the reductions in significantly, depending on figures below are for annual net annual cooling load made climate, the specific design of heating benefits. The natural possible by the use of natural the system, and the way it is cooling section in Part Three cooling). The natural cooling built and operated. Of course, gives advice about shading and gUidelines should make the energy performance is not the other techniques which would house's total cooling load - the only consideration. A system make sure the winter heating bottom line of this Worksheet, in which will give excellent energy benefits are not at the expense Btu/yr-sf - smaller than in a performance may not be as of higher summer cooling loads. "conventional" house. The lower marketable in your area or as Please note that throughout the cooling performance level, easily adaptable to your designs the Guidelines and Worksheets the better the design. as a system which saves less the glazing areas given are for So, the Worksheets provide energy but fits other needs. the actual net area of the glass four key numbers indicating the In the following table, itself. A common rule of thumb projected performance of the several different passive solar is that the net glass area is 80 various designs you are systems are presented along percent of the rough frame evaluating. with two numbers which .opening. For example, if a • The Worked Example: To indicate their performance. The south glass area of 100 sf is aSSist in understanding how the Percent Solar Savings is a deSired, the required area of the design strategies outlined in the measure of how much the rough frame opening would be GUidelines affect the overall passive solar system is reducing about 125 sf. performance of a house, a the need for purchased energy. worked example is included. For example, the Percent Solar The example house is assumed Savings for the Base Case House to be constructed of materials is 3.5%, because even in a non­ and design elements typical of solar house, the south-facing the area. Various design windows are contributing some features, such as direct gain heat energy. spaces, sunspaces, increased The Yield is the annual net levels of insulation and thermal heating energy benefit of adding mass, are included to illustrate the passive solar system, the effects combined systems measured in Btu saved per year have on the performance of a per square foot of additional house. Also, many features are south glazing. covered to demonstrate how The figures given are for a various conditions and 1,500 sf, Single-story house with situations are addressed in the a basement. The Base Case worksheets. A description of the House has 45 sf of south-facing design features, along with the glazing. For the purposes of this house plans, elevations and example, the Suntempered sections, is included for house has 100 sf of south-faCing additional support information. glass, and each passive solar

Green Bay. Wisconsin 6 GUIDELINES PART ONE: INTRODUCTION

Performance Potential of Passive Solar Strategies in Green Bay, Wisconsin 1,500 sf, Single Story House Yield Btu Saved per Percent Solar Square Foot of Case Savings South Glass

Base Case 3.5 not applicable (45 sf of south-facing double glass) Suntempered 6.5 26,682 (100 sf of south-facing double glass)

Direct Gain (145 sf of south glass) Double Glass 8.2 22,210 Triple or low-e glass 11.0 49,557 Double glass with R-4 night 13.8 73,500 insulationl Double glass with R-9 night 15.0 83,594 insulation 1

Sunspace (145 sf of south glass) Attached with opaque end walls2 10.6 50,518 Attached with glazed end walls2 9.9 44,636 Semi-enclosed with vertical glazing3 9.0 31,555 Semi-enclosed with 50° sloped 13.3 69,199 glazing3

Thermal Storage Wall - Masonry/Concrete (145 sf of south glass) Black surface, double glazing 8.4 31,141 Selective surface, single glazing 12.5 64,498 Selective surface, double glazing 12.3 63,798

Thermal Storage Wall - Water Wall (145 sf of south glass) Selective surface, single glazing 14.6 78,882

1. Night insulation is assumed to cover the south glass each night and removed when sun is available. Experience has shown that many homeowners find this inconvenient and so the potential energy savings are often not achieved. Using low-e or other energy-efficient glazing is more reliable. 2. The attached sunspace is assumed to have, in addition to glazed walls, roof glazing at a slope of 30 degrees from the horizontal, or a 7:12 pitch. (See diagram SSB1 in the Worksheets.) 3. The semi-enclosed sunspace has only the south wall exposed to the out­ of-doors. The glazing has a slope of 50° from the horizontal, or a 14:12 pitch. The side walls are adjacent to conditioned space in the house. (See diag"ram SSD1 in the Worksheets.)

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Part Two: Basics of Passive Solar

1. Why Passive Solar? More than a Question of Energy

2. Key Concepts: Energy Conservation, Suntempering,

3. "Improving Conservation Performance

4. Mechanical Systems

5. South-Facing Glass

6. Thermal Mass

7. Orientation

8. Site Planning for Solar Access

9. Interior Space Planning

10. Putting it Together: The Bouse as a System

Green Bay, Wisconsin 8 GUIDELINES PART TWO: BASIS OF PASSIVE SOLAR

1. Why Passive Solar? improve energy-efficiency - but as the state of the art in energy­ More than a Question added insulation is invisible to efficiency and style, and they the prospective home buyer. A use passive solar as a part of the of Energy sunny, open living area lit by package. south-facing windows, on the The U.S. Department of Houses today are more energy­ other hand, may be a key selling Energy and the National Renew­ efficient than ever before. pOint. Windows in general are able Energy Laboratory (NREL) However, the vast majority of popular with homebuyers, and conducted extensive national new houses still ignore a lot of passive solar can make windows surveys of passive solar homes, energy saving opportunities - energy producers instead of home owners and potential opportunities available in the energy liabilities. buyers. Some key findings: sunlight falling on the house, in Another example: high­ • Passive solar homes work - the landscaping, breezes and efficiency heating equipment they generally require an other natural elements of the can account for significant average of about 30% less site, and opportunities in the energy savings - but it won't be , energy for heating than structure and materials of the as much fun on a winter "conventional" houses, with house itself, which, with morning as breakfast in a some houses savi~g much more. thoughtful design, could be bright, attractive sunspace. • Occupants of passive solar used to collect and use free The point is not that a homes are pleased with the energy. Passive solar (the name builder should choose passive performance of their homes distinguishes it from "active" or solar instead of other energy­ (over 90% "very satisfied"), but mechanical solar technologies) conseIVing measures. The they rank the comfort and is simply a way to take important thing is that passive pleasant living environment as maximum advantage of these solar strategies can add not only just as important (in some opportunities. energy-efficiency, but also very regions, more important) to their Home buyers are also saleable amenities - style. satisfaction, and in their increasingly sophisticated about comfort. attractive interiors, deCision to buy the house, as energy issues, although the curb appeal and resale value. energy considerations. average home buyer is probably In fact. in some local • Passive solar home owners much more familiar with markets, builders report that and lenders perceive the insulation than with passive they don't even make specific resale value of passive solar solar. The "energy crisis" may reference to "passive solar". houses as bigh. come and go, but very few They just present their houses people perceive their own Advantages of Passive Solar household energy bills as • Energy performance: Lower energy bills all year-round getting smaller - quite the opposite. So a house with • Attractive living environment: large windows and views, sunny significantly lower monthly interiors, open floor plans energy costs year-round will • Comfort: quiet (no operating noise), solid construction, warmer in have a strong market advantage winter, cooler in summer (even during a power failure) over a comparable house down the street, no matter what • Value: high owner satisfaction, high resale value international oil prices may be. • Low Maintenance: durable, reduced operation and repairs There are many different ways to reduce energy bills, and • Investment: independence from future rises in fuel costs, will. continue some are more marketable than to save money long after any initial costs have been recovered others. For instance, adding • Environmental Concerns: clean, renewable energy to combat growinr insulation can markedly concerns over lobal warmin ,acid rain and ozone de letion

Green Bay. Wisconsin 2. Key Concepts: Many of the measures that Although the concept is simple. are often conSidered part of in practice the relationship Energy Conservation, suntempertng or passive solar - between the amounts of glazing Suntempering, such as orienting to take and mass is complicated by Passive Solar advantage of summer breezes. or many factors. and has been a landscaping for natural cooling. subject of conSiderable study or facing a long wall of the and experiment. From a comfort The strategies for enhancing house south - can help a house and energy standpoint, it would energy performance which are conserve energy even if no be difficult to add too much presented here fall into four "solar" features are planned. mass. Thermal mass will hold general categories: The essential elements in a warmth longer in winter and • Energy Conservation: passive solar house are south­ keep houses cooler in summer. insulation levels. control of air facing glass and thermal mass. The following sections of the infiltration. glazing type and In the simplest terms. a GUidelines discuss the size and location. mechanical equipment passive solar system collects location of glass and mass. as and energy effiCient appliances. solar energy through south­ well as other considerations • Suntempering: a limited use faCing glass and stores solar which are basic to both of solar techniques; modestly energy in thermal mass - suntempered and passive solar increasing south-facing window materials with a high capaCity houses: improving conservation area, usually by relocating for storing heat (e.g .. briCk. performance; mechanical windows from other sides of the concrete masonry. concrete systems; orientation; site house. but without adding slab. tile. water). The more planning for solar access; thermal mass. south-facing glass is used in the interior space planning; and • Solar Architecture: going house. the more thermal mass approaching to the house as a beyond conservation and must be provided. or the house totally integrated system. suntempering to a complete will overheat and the solar system of collection. storage and system will not perform as use of solar energy: using more expected. south glass. adding appropriate Improperly done. passive thermal mass. and taking steps solar may continue to heat the to control and distribute heat house in the summer. causing energy throughout the house. discomfort or high air­ • Natural Cooling: using conditioning bills. or overheat design and the environment to the house in the winter and cool the house and increase require additional ventilation. comfort. by increasing air movement and employing shading strategies. What is immediately clear is that these categories overlap. A good passive solar design must include an appropriate thermal envelope. energy efficient mechanical systems. energy effiCient appliances and proper solar architecture. specifically the appropriate amounts and locations of mass and glass.

Green Bay t Wisconsin 10 GUIDELINES PART TWO: BASIS OF PASSIVE SOLAR

3. Improving The thennal resistance of Slab edge insulation should ceiling/roof assembUes. walls be at least two feet deep, Conservation and floors is affected not only extending from the surface of Performance by the R-value of the insulation the floor or above. Materials for itself, but also the resistance of slab edge insulation should be The techniques desCribed in this other elements in the selected for underground section relate to Worksheet I: construction assembly - framing durability. One material with a Conservation Performance effects, exterior sheathing, and proven track record is extruded Level, which measures the finishes and interior finishes. polystyrene. Exposed insulation house's heat loss. The energy The Worksheets include tables should be protected from conseIVation measures that that show Equivalent ,. physical d~age by attaching a reduce heat loss also tend to Construction R-Values which protection board, for instance, reduce the house's need for air account for these and other or by covering the insulation conditioning. effects. For instance, ventilated with a protective surface. The The most important crawlspaces and unheated use of termite shields may be measures for improving the basements provide a buffering required. house's basic ability to conseIVe effect which is accounted for in Heated basement walls the heat generated either by the the Worksheet tables. should be fully insulated to at sun or by the house's With attics, framing effects least four feet below grade, but conventional heating system are are minimized if the insulation the portion of the wall below in the following areas: covers the ceiling joists, either that depth only needs to be • Insulation by using blown-in insulation or insulated to about half the R­ • Air infiltration by running an additional layer value of the upper portion. • Non-solar glazing of batts in the opposite direction Insulation can be placed on the of the ceilingjoists. Ridge outside surface of the wall, or on Insulation and/ or eave vents are needed for the inside surface of the wall, or Adding insulation to walls, ventilation. in the cores of the masonry floors, ceilings, roof and units. foundation improves their lf the basement walls are thennal resistance (R-value) - insulated on the outside. the their resistance to heat flowing materials should be durable out of the house. underground. and exposed A quality job of installing the insulation should be protected insulation can have almost as from damage. Exterior much effect on energy insulation strategies only perfonnance as the R-value, so Insulation in an Attic require the use of a tennite Insulation should extend over the top ceiling shield. In the case of a finished careful construction supervision joists and ventilation should be provided at the is important. An inspection just eaves. basement or walk-out basement. before the drywall is hung may placing insulation on the identify improvements which are In cathedral ceilings, an interior or within the cores of easy at that time but might insulating sheathing over the architectural masonry units make a big difference in the top decking will increase the R­ may be less costly than energy use of the home for the value. insulating the exterior life of the building. foundation.

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Air Infiltration Checklist for Minimizing Air Leakage Sealing the house carefully to ./ Tighten seals around windows and doors. and weatherstripping around reduce air infiltration - air all openings to the outside or to unconditioned rooms; leakage - is as necessary to ./ Caulk around all windows and doors before drywall is hung; seal all energy conservation as adding penetrations (plumbing, electrical. etc.); insulation. The tightness of houses is ./ Insulate behind wall outlets and/or plumbing lines in exterior walls; generally measured in the ./ Caulk under headers and sills; number of air changes per hour ./ Chink spaces between rough openings and millwork with insulation, or (ACH). A good. comfortable. for a better seal, fill with foam; energy-efficient house. built along the guidelines in the table ./ Seal larger openings such as ducts into attics or crawlspaces with taped polyethylene covered with insulation; on this page. will have approximately 0.35 to 0.50 air ./ Locate continuous vapor retardants located on the warm side of the changes per hour under normal insulation (building wrap, continuous interior polyethylene, etc.); winter conditions. ./ Install dampers and/or glass doors on fireplaces; combined with outside Increasing the tightness of combustion air intake; the house beyond that may ./ Install backdraft dampers on all exhaust fan openings; improve the energy performance. ./ Caulk and seal the joint between floor slabs and walls; but it may also create problems with indoor air quality. moisture ./ Remove wood grade stakes from slabs and seal; build-Up. and inadequately ./ Cover and seal sump cracks; vented fireplaces and furnaces. Some kind of additional ./ Close core voids in top of concrete masonry foundation walls; mechanical ventilation - for ./ Control concrete and masonry cracking; example. small fans. heat pump heat exchangers. integrated ./ Use of air tight drywall methods are also acceptable; ventilation systems or air~to-air ./ Employ appropriate radon mitigation techniques. heat exchangers - will probably ./ Seal seams in exterior sheathing. be necessary to avoid such problems in houses with less than 0.35 ACH (calculated or measured). Tighter houses may perform effectively with appropriate mechanical ventilation systems. The use of house sealing subcontractors to do the tightening and check it with a blower door can often save the builder time and problems. especially when trying to achieve particularly high levels of infiltration control.

Green Bay. Wisconsin 12 GUIDELINES PART TWO: BASIS OF PASSIVE SOLAR

Non-50lar Glazing R-values that result from be balanced against the South-faCing windows are procedures account for the benefits. considered solar glazing. The glass. the frame. the air gap and As many windows as south windows in any house are any special (low-e) coatings. possible should be kept operable contributing some solar heat North windows should be for easy natural ventilation in energy to the house's heating used with care. Sometimes summer. (See also Ortentation. needs - whether it's a views or the diffuse northern page 16. Recommended Non­ signtficant. usable amount or light are desirable. but in South Glass Guidelines. page hardly worth measuring will general north-facing windows 34. and Shading. page 35) depend on design. location and should not be large. Very large other factors which are dealt north-facing windows should Low-e Glass with later under the discussions have high insulation value. or The principle mechanism of heat of suntempering and passive R-value. Since north windows transfer in multi-layer glazing is solar systems. receive relatively little direct sun thermal radiation from a warm North windows in almost in summer. they do not present pane of glass to a cooler pane. every climate lose signtficant much of a shading problem. So Coating a glass surface with a heat energy and gain very little if the chOice were between an low-emissivity (low-e) metallic useful sunlight in the winter. average-sized north-facing oxide material and facing that East and west windows are window and an east or west­ coating into the gap between the likely to increase air facing window. north would glass layers significantly conditioning needs unless heat actually be a better chOice. reduces the amount of heat gain is minimized with careful considering both summer and transfer. The improvement in attention to shading. winter performance. insulating value due to the But most of the reasons East windows catch the low-e coating is roughly people want windows have very morning sun. Not enough to equivalent to adding another little to do with energy. so the provide Significant energy. but. layer of glass to the multi-pane best design will probably be a unfortunately. usually enough glass unit. Two panes of glass. good compromise between to cause potential overheating one with a low-e coating. will energy efficiency and other problems in summer. If the have about the same insulating. benefits. such as bright living views or other elements in the value as three clear panes. Add spaces and views. house's design dictate east argon gas to this two pane low-e Triple-glazing or double­ windows. shading should be unit and the system will be glazing with a low-e coating is done with particular care. nearly as effective as four layers advisable. Low-e glazing on all West windows may be the of clear glass. The net effect to non-solar windows may be an most problematic. and there are the building occupant is an especially useful solution few shading systems that will be improvement in comfort in both because some low-e coatings effective enough to offset the winter and summer. can insulate in winter and potential for overheating from a In the market today. there shield against unwanted heat large west-facing window. Glass are three basic types of low-e gain in summer. with a low shading coefficient coatings: (1) high transmission A chart is provided with the may be one effective approach - low-e. (2) selective transmission worksheets that gives typical for example. tinted glass or low-e. and: (3) tinted low-e or window R-values for generic some types of low-e glass which tinted glass with low-e. window types. When possible. provide some shading while These categories are related however. manufacturer's data allowing almost clear views. The to the windows' transmission of based on National Fenestration cost of properly shading both sunlight. or Solar Heat Gain Rating Council (NFRC) east and west windows should (SHG) coefficient. The SHG· procedures should be used. The coefficient will soon be made

Green Bay, Wisconsin t'AtitilVI:: tiUlJ\H Uc;:,/u/v ;:, I MM I CU/Cv available to builders and 4. Mechanical • Ducts: One area often consumers from uniform ratings neglected but of key importance made by the NFRC. Systems to the house's energy High transmission products performance is the design and are best suited to passive solar The passive solar features in the location of the ducts. Both the buildings designs located in house and the mechanical supply and return ducts should heating dominated climates heating. ventilating and air be located within insulated where high solar gains can be conditioning systems (HVAC) areas. or be well insulated if utilized by thermal mass and will interact all year round. so they run in cold areas of the where overhangs are the most effective approach will house. All segments of ducts incorporated to prevent be to design the system as an should be sealed at the jOints. unwanted summer heat gains. integrated whole. HVAC design The joints where the ducts turn Selective transmission is. of course. a complex subject. up into exterior walls or products are ideal for those but four areas are particularly penetrate the ceiling should be buildings that have both winter worth noting in energy-efficient particularly tight and sealed. heating and summer cooling houses: • System Efficiency: Heating requirements. The low • System Sizing: Mechanical system efficiency is rated by the emittance characteristics of this systems are often oversized for annual fuel utilization efficiency glass ensure winter performance the relatively low heating loads (AFUE). Cooling system by a reduction in heat loss. In in well-insulated passive solar efficiency is rated by the summer. the selective properties houses. Oversized systems will seasonal efficiency is rating allow natural daylighting. but cost more in the first place. and (SEER). The higher the number. block a large fraction of solar will cycle on and off more often. the better the performance. infrared energy. reducing the wasting energy. The back-up In the National Association cooling load. systems in passive solar houses of Home Builders' Energy­ Putting a low-e coating on should be sized to provide 100% Efficient House Project. all the tinted glass. or coloring the of the heating or cooling load on rooms were fed with low. central coating itself. creates a product the design day. but no larger. air supplies. as opposed to the with the U-value. or insulating Comparing estimates on system usual placement of registers capability. of both the products sizes from more than one under windows at the end of above. However. this glass also contractor is probably a good long runs. This resulted in good provides glare control along with idea. comfort and energy a high level of solar heat • Night Setback: Clock performance. rejection. helping control solar thermostats for automatic The performance of even the gains in cooling dominated setback are usually very most beautifully designed areas. effective - but in passive solar passive solar house can easily With this range of products systems with large amounts of be undermined by details like available in the market. nearly thermal mass (and thus a large uninsulated ducts. or by all buildings can benefit from capacity for storing energy and overlooking other basiC energy the application of low-e glass. releasing it during the night). conservation measures. Home owners will enjoy setback of the thermostat may increased comfort and livability not save very much energy in interior spaces. reduced unless set properly to account operating costs. and possibly for the time lag effects resulting first cost savings from reduced from the thermal mass. HVAC eqUipment sizing.

Green Bay, Wisconsin - 14 GUIDELINES PART TWO: BASIS OF PASSIVE SOLAR

5. South-Facing Glass The third limit on south­ When the solar glazing is facing glass is the total of all tilted. its winter effectiveness as South-facing solar glass is a key passive solar systems combined. a solar collector usually component of any passive solar which should not exceed 20% of increases. However. tilted system. The system must total floor area. Using more glazing can cause serious include enough solar glazing for south glass than this limit could overheating in the summer if it good performance in winter. but lead to overheating even in is not properly shaded. not so much that cooling winter. Ordinary vertical glazing is easier to sha~e. less likely to performance in summer will be For example. a passive solar overheat. less susceptible to compromised. The amount of system for a 1, 500 sf house might combine 150 sf of direct damage and leaking. and so is solar glazing must also be almost always a better year­ carefully related to the amount gain glazing with 120 sf of round solution. Even in the of thermal mass. Suntempered sunspace glazing for a total of 270 sf of solar glazing. or 18% of winter. with the sun low in the houses use no additional sky and reflecting off snow thermal mass beyond that the total floor area. well within the direct gain limit of 12% and cover. vertical glazing can often already in the wallboard. the overall limit of 20%. For a offer energy performance just as framing and furnishings of a effective as tilted. typical house. Houses with design like this. thermal mass would be required both in the solar architecture must have additional thermal mass. house and within the sunspace. There are three types of The Natural Cooling gUidelines in Part Three include limits on the amount of south­ facing glass that can be used recommendations on the effectively in a house. The first window area that should be is a limit on the amount of operable to allow for natural glazing for suntempered houses. ventilation. 7% of the house's total floor area. Above this 7% limit. mass must be added. For direct gain systems in passive solar houses. the maximum amount of south­ facing glazing is 12% of total floor area. regardless of how much additional thermal mass is provided. This limit will reduce the problems associated with visual glare or fabriC fading. Further details about the most effective sizing of south glass and thermal mass for direct gain systems are provided in Part Three.

Green Bay. Wisconsin 6. Thermal Mass The thermal storage The design issues related to capabilities of a given material thermal mass depend on the Some heat storage capacity. or depend on the material's passive system type. For thermal mass. is present in all conductivity. specific heat and sunspaces and thermal storage houses. in the framing. gypsum density. Most of the concrete wall systems. the required mass wallboard. typical furnishings and masonry materials typically of the system is included in the and floor coverings. In used in passive solar have design itself. For direct gain. suntempered houses. this similar specific heats. the added mass must be within Conductivity tends to increase the rooms receiving the modest amount of mass is sunlight. The sections on Direct sufficient for the modest amount with. increasing density. So the Gain Systems. Sunspaces and . of south-facing glass. But more major factor affecting thermal mass is required in performance is density. Thermal Storage Walls contain passive solar houses. and the Generally. the higher the more information on techniques question is not only how much. density the better. for sizing and locating thermal but what kind and where it mass in those systems. should be located. The thermal mass in a passive solar system is usually a conventional construction Heat Storage Properties of Materials material such as brick, poured Material Specific Density Heat concrete. concrete masonry. or Heat (lb/ft3) Capacity tile. and is usually placed in the (BtU/lb OF). (BtU/in-sf-OF) floor or interior walls. Other materials can also be used for Poured Concrete 0.16-0.20 120 -150 2.0 - 2.5 thermal mass. such as water or "phase change" materials. Clay Masonry 0.19-0.21 Phase change materials store Molded Brick 120 -130 2.0 - 2.2 and release heat through a Extruded Brick 125 - 135 2.1 - 2.3 chemical reactions. Water Pavers 130 -135 2.2 - 2.3 actually has a higher unit thermal storage capacity than Concrete Masonry 0.19-0.22 concrete or masonry. Water Concrete Masonry Units 80 - 140 1.3 - 2.3 tubes and units called "water Brick 115-140 1.9 - 2.3 walls" are commercially Pavers 130 -150 2.2 - 2.5 available (general recommendations for these Gypsum Wallboard 0.26 50 1.1 systems cu:e included in the section on Thermal Storage Wall Water 62.4 5.2 systems).

Green Bay. Wisconsin 16 GUIDELINES PART TWO: BASIS OF PASSIVE SOLAR

7. Orientation When glazing is ortented In the ideal Situation. the more than 15 degrees off true house should be ortented east­ The ideal ortentation for solar south. not only is winter solar west and so have its longest wall glazing is within 5 degrees of performance reduced. but facing south. But as a practical true south. This ortentation will summer air conditioning loads matter. if the house's short side provide maximum performance. also significantly increase. has good southern exposure it Glazing ortented to within 15 especially as the ortentation will usually accommodate degrees of true south will goes west. The warmer the sufficient glazing for an effective perform almost as well. and climate. the more east- and passive solar system. provided ortentations up· to 30 degrees off west-facing glass will tend to the heat can be transferred to the northern zones of the house. - although less effective - will cause overheating problems. In still provide a substantial level general. southeast ortentations of solar contrtbution. present less of a problem than In Green Bay. magnetic southwest. Magnetic north as indicated on the North compass is actually 1 degrees East of true north. and this North should be corrected for when planning for ortentation of south glazing.

Magnetic De"iatlll)n Magnetic Diviation is the angle between true north and magnetic north.

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8. Site Planning for situation for providing unshaded southern exposure Solar Access during the winter. See also the figure on page 35 showing The basic objective of site landscaping for summer shade. planning for maximum energy performance is to allow the cm __ ,_~ __ m,1 I south side as much unshaded exposure as possible during the ~~ winter months. :...... L ...... ) ...... : Solar Subdivision Layouts As discussed above. a good Solar access may be provided to the rear solar orientation is possible yard, the side yard or the front yard of solar homes. within a relatively large ~ 2 Story Buildings Allowed southern arc. so the flexibility Ideal Solar Access exists to achieve a workable Buildings, trees or other obstructions should balance between energy not be located so as to shade the south wall of solar buildings. At this latitude, A = 19 ft., B = performance and other 34 ft., and C = 77 ft. important factors such as the slope of the site. the individual Of course. not all lots are large house plan. the direction of enough to accommodate this prevailing breezes for summer kind of optimum solar access. so cooling. the views. the street lay­ it's important to carefully assess out. and so on. shading patterns on smaller lots But planning for solar to make the best compromise. access does place some Protecting solar access is restrictions even on an easiest in subdivisions with ~ Solar Subdivision Layouts individual Site. and presents streets that run within 25 Short east-west CUl-de-sacs tied into north­ even more challenges when degrees of east-west. because all south collectors is a good street pattern for solar access. planning a complete lots will either face or back up to subdivision. Over the years. south. Where the streets run Two excellent references for developers and builders of many north- south. creation of east­ ideas about subdivision lay-out different kinds of projects all west cul-de-sacs will help to protect solar access are over the country have come up ensure solar access. Builder's Guide to Passive Solar with flexible ways to provide Home Design and Land adequate solar access. Development and Site Planning Once again. there is an ideal jar Solar Access. situation and then some degree of flexibility to address practical concerns. Ideally. the glazing on the house should be exposed to sunlight with no obstructions within an arc of 60 degrees on either side of true south. but reasonably good solar access will still be guaranteed if the glazing is unshaded within an arc of 45 degrees. The figure on this page shows the optimum

Green Bay. Wisconsin 18 GUIDELINES PART TWO: BASIS OF PASSIVE SOLAR

9. Interior Space Another general principle is 10. Putting it that an open floor plan will Planning allow the collected solar heat to Together: The House circulate free1y through natural as a System Planning room lay-out by convection. considering how the rooms will Other ideas from effective Many different factors will affect be used in different seasons, passive solar houses: a house's overall performance. and at different times of day, • Orienting internal mass and these factors all interact: can save energy and increase walls as north-south partitions the mechanical system, the comfort. In houses with passive that can be "charged" on both insulation. the house's solar features, the lay-out of sides. tightness. the effects of the rooms - and interior zones • Using an east-west partition passive solar features, the which may include more than wall for thermal mass. appliances, and, very one room - is particularly • Avoid dividing the house important1y. the actions of the important. between north and south zones. people who live in the house. In In general, living areas and • Using thermal storage walls each of these areas. changes are other high-activity rooms should (see page 30); the walls store possible which would improve be located on the south side to energy all day and slowly release the house's energy performance. benefit from the solar heat. The it at night. and can be a good Some energy savings are closets, storage areas, garage alternative to ensure privacy relatively easy to get. Others and other less-used rooms can and to buffer noise when the can be more expensive and more act as buffers along the north south side faces the street; difficult to achieve, but may side, but entry-ways should be • Collecting the solar energy provide benefits over and above located away from the wind. in one zone of the house and good energy performance. Clustering baths, kitchens and transporting it to ariother by A sensible energy-efficient laundry-rooms near the water fans or natural convection house uses a combination of heater will .save the heat that through an open floor plan. techniques. would be lost from longer water • PrOviding south-facing In fact. probably the most lines. clerestories to "charge" north important thing to remember ...... "' ...... ~ ...... ;...... ; ...... :" zones. about designing for energy ....." .. m." .. ,. ../' Buffer Spaces \ .f \: i Bed- 1( Closets, Stairs, 'it Garage 'i performance in a way that will also enhance the comfort and ~~~~'~ value of the house is to take an \ room ;: / L" \ :: Kltchen/Dlmng> integrated approach. keeping in •••••••".~ ...... / (\~.~::•••• ) •••••••••••••• h •••. ~_• ..,.~ ••,····'>' mind the house as a total system. On the the following ~ page is a basiC checklist for Interior Space Planning energy-efficient design. These Uving and high activity spaces should be techniques are dealt with in located on the south. more detail, inclUding their impact in your location. in Part Three.

Green Bay, Wisconsin Checklist for Good Design ./ 1. Building Orientation: A number of innovative techniques can be used for obtaining good solar access. No matter what the house's design, and no matter what the site, some options for orientation will be more energy­ efficient than others, and even a very simple review of the site will probably help you choose the best option available . ./ 2. Upgraded levels of insulation: It is possible, of course, to achieve very high energy-efficiency with a "superinsulated" design. But in many cases, one advantage of passive solar design is that energy-efficiency can be achieved with more economical increases in insulation. On the other hand, if very high energy performance is a priority - for example, in areas where the cost of fuel is high - the most cost-effective way to achieve it is generally through a combination of high levels of insulation and passive solar features . ./ 3. Reduced air infiltration: Air tightness is not only critical to energy performance, but it also makes the house more comfortable. Indoor air quality is an important issue, and too complex for a complete discussion here, but in general, the suntempered and passive solar houses built according to the Guidelines provide an alternatiVe approach to achieving improved energy efficiency without requiring air quality controls such as air to air heat exchangers, , which would be needed if the house were made extremely airtight. ./ 4. Proper window sizing and location: Even if the total amount of glazing is not changed, rearranging the location alone can often lead to significant energy savings at little or no added cost. Some energy-conserving designs minimize window area on all sides of the house - but it's a fact of human nature that people like windows, and windows can be energy producers if located correctly . ./ 5. Selection of glazing: Low-emissivity (low-e) glazing types went from revolutionary to commonplace in a very short time, and they can be highly energy-efficient choices. But the range of glazing possibilities is broader than that, and the choice will have a significant impact on energy performance. Using different types of glazing for windows with different orientations is worth considering for maximum energy performance; for example, using heat-rejecting glazing on west windows, high R-value glazing for north and east windows, and clear double-glazing on solar glazing . ./ 6. Proper shading of windows: If windows are not properly shaded in summer - either with shading devices, or by high-performance glazing with a low shading coefficient - the air conditioner will have to work overtime and the energy savings of the winter may be canceled out. Even more important, unwanted solar gain is uncomfortable . ./ 7. Addition of thermal mass: Adding thermal mass - tiled or paved concrete slab, masonry walls, brick fireplaces, tile floors, etc. - can greatly improve the comfort in the house, holding heat better in winter and keeping rooms cooler in summer. In a passive solar system, of course, properly sized and located thermal mass is essential. ./ 8. Interior design for easy air distribution: If the rooms in the house are planned carefully, the flow of heat in the winter will make the passive solar features more effective, and the air movement will also enhance ventilation and comfort during the summer. Often this means the kind of open floor plan which is highly marketable in most areas. Planning the rooms with attention to use patterns and energy needs can save energy in other ways, too - for instance, using less-lived-in areas like storage rooms as buffers on the north side . ./ 9. Selection and proper sizing of mechanical systems, and selection of energy-efficient appliances: High-performance heating, cooling and hot water systems are extremely energy-efficient, and almost always a good investment. Mechanical equipment should have at least a 0.80 Annual Fuel Utilization Efficiency (AFUE). Well-insulated passive solar homes will have much lower energy loads than conventional homes, and should be sized accordingly. Oversized systems will cost more and reduce performance.

Green Bay. Wisconsin 20 GUIDELINES PART TWO: BASIS OF PASSIVE SOLAR

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Part Three: Strategies for ~mproving Energy Performance in Green Bay, Wisconsin 1. The Example Tables

2. Suntempering

3. Direct Gain

4. Sunspaces

5. Thermal Storage Wall

6. Combined Systems

7. Natural Cooling Guidelines

Green Bay, Wisconsin 22 GUIDELINES PART THREE: STRATEGIES FOR IMPROVING ENERGY PERFORMANCE

1. The Example • Three numbers The R-values indicated in corresponding to those on the the Example tables are. of Tables Worksheets: Conservation. course. approximate and are Auxillary Heat. and Cooling intended to show how In the following sections of the Performance incremental improvemeI.1ts can Guidelines. the primruy passive The Example tables then show be achieved. All R-values in the solar energy systems - how the house design could be Examples and Worksheets are Suntempertng. Direct Gain. changed to reduce winter equivalent R-values for the Thermal Storage Walls and heating energy by 20. 40 and entire construction assembly. Sunspaces - are described in 60%. compared to this Base not just for the cavity insulation more detail. Case House. itself. and take into account As part of the explanation of There are. of course. other framing and buffering effects. each system. an Example table ways to achieve energy savings Other assumptions are is provided. The Examples than those shown in the noted for each Example. present the following Examples. The Examples are However. one more general information about a Base Case designed to show an effective assumption is important to note House. based on a National integration of strategies. and a here. When the Examples were Association of Home Builders useful approach to the design of calculated. it was assumed that study of a typical construction: the house as a total system. natur~ cooling strategies such • Insulation levels (ceilings. Using any of these combinations as those described in these walls. floors); would result in excellent Guidelines were used. • Insulation added to the performance in your area. particularly in the very high­ perimeter of the basement walls; However. they are general performance systems. The • Tightness (measured in air indications only. and using the greater the percentage reduction changes per hour. ACH); . Worksheets will give you more in heating energy needs using • The amount of glass area on information about your specific passive solar design. the more each side (measured as a design. shading and natural cooling percentage of floor area; the The Example assumes a were assumed. actual square footage for a 1.500 1.500 sf house. but the The Examples show passive sf house is also given as a percentages apply to a house of solar strategies. but an Added reference point); any size or configuration. Insulation Example table • The "percent solar savings" (achieving energy savings only (the part of a house's heating by increasing insulation levels. energy saved by the solar without specific solar features) features); and is provided in the Summary beginning on page 82.

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2. Suntempering Examples of Heat Energy Savings Suntempered Both suntempered and passive 1,500 sf Single Story House (in a specific location) solar houses: • begin with good basic Base energy-conservation. Case 20% 40% 60% • take maximum advantage of R-Values the building site through the Ceiling/Roof 31 36 44 60 Walls 19 22 27 38 right orientation for year-round Basement Wall 11 13 16 23 energy savings. and Glass 1.8 1.8 2.7 3.3 • have increased south-facing glass to collect solar energy. Air Changes/Hour 0.50 0.42 0.37 0.26 Suntempering refers to Glass Area (percent of total floor area) modest increases in windows on West 3.0% 2.0% 2.0% 2.0% the south side. North 3.0% 4.0% 4.0% 4.0% No additional thermal mass East 3.0% 4.0% 4.0% 4.0% South 3.0% 6.7% 6.7% 6.7% is used. only the "free mass" in the house - the framing. Solar System Size (square feet) gypsum wall-board and South Glass 45 100 100 100 furnishings. Percent Solar Savings In a "conventional" house. 3% 10% 12% 16% about 25% of the windows face south. which amounts to about Performance (Btu/yr-sf) 3% of the house's total floor Conservation 52,730 46,732 36,139 25,497 Auxiliary Heat 50,890 41,719. 31,522 21,298 area. In a suntempered house, Cooling 5,138 2,556 1,556 564 the percentage is increased to a maximum of about 7% of the Summary: Insulation values and tightness of the house (as measured in ACH) have been increased. The window area has been slightly floor area. decreased on the west, increased slightly on the east and north, and The energy savings are more increased significantly on the south. modest with this system. but suntempering is a very low-cost Note: These examples should not be construed as recommendations - the numbers represent the effect of changes in design required to achieve the strategy. exact savings in annual auxiliary heat. In practice, the designer has great Of course, even though the latitude in selecting values to use. necessity for precise sizing of glazing and thermal mass does not apply to suntempering (as long as the total south-facing glass does not exceed 7% of the total house floor area), all other recommendations ,about energy­ effiCient design such as the basic energy conservation measures, room lay-out. siting, glazing type and so on are still important for performance and comfort in suntempered homes.

Green Bay, Wiscons~ 24 GUIDELINES PART THREE: STRATEGIES FOR IMPROVING ENERGY PERFORMANCE

3. Direct Gain used in the design, as discussed where the winter sun will fall below. directly on it. The most common passive solar Effective materials for floors strategy system is called direct Glazing include painted, colored or gain: sunlight through south­ Triple glazing or double glazing vinyl- covered concrete, brick facing glazing falls directly into with a low-e coating is (face brick or pavers have even the space to be heated, and is recommended for direct gain higher density than ordinary stored in thermal mass glazing in Green Bay. The building brick), quarry tile, and incorporated into the floor or Performance Potential table on dark-colored ceramic tile lead interior walls. The south page 6 shows the relative directly on the slab. window area is increased above performance of different types of For houses built with the 7% limit of a suntempered direct gain glazing. You will crawlspaces or basements, the house, and additional thermal note from this table that yield incorporation of significant mass is added to store the increases by 123% between amounts of heavy thermal mass additional solar gains and thus double and triple or low-e is a little more difficult. Thermal prevent overheating. glazing. Night insulation also mass floor coverings over improves energy performance basements, crawlspaces and dramatically. In fact. as the lower stories would generally be Performance Potential table limited to thin set tile or other shows, covering the windows at thin mass floors. night or on cloudy days with the When more mass is required, equivalent of R-4 shades or the next best option is for other material will save almost interior walls interior finishes or as much energy as with R-9 exterior walls or interior material. But studies have masonry fireplaces. When shown that only relatively few evaluating costs, the dual homeowners will be diligent function of mass walls should Direct Gain enough about operating their be remembered. They often Direct gain is the most common passive solar night insulation to achieve those serve as structural elements or system in residential applications savings. Energy-efficient for fire protection as well as for glazing, on the other hand, thermal storage. Another option Sizing Limit needs no operation, and is to switch to another passive Total direct gain glass area therefore is a more convenient solar system type such as should not exceed about 12% of and reliable option. attached slab-on-grade the house's floor area. Beyond sunspaces or thermal storage that, problems with glare or Thennal Mass walls built directly on exterior fading of fabriCS are'more likely Thermal mass can be foundation walls. to occur, and it becomes more incorporated easily into houses Sunlit thermal mass floors difficult to provide enough with slab-on-grade floors by should be relatively dark in thermal mass for year:-round exposing the mass. The mass is color. to absorb and store energy comfort. much more effective if sunlight . more effectively. However. mass So the total south-facing falls directly on it. Covering the walls and ceilings should be glass area in a direct gain mass with any insulation light in color to help distribute system should be between 7% material. such as carpet, greatly both heat and light more evenly. (the maximum for suntempered reduces its effectiveness. A good houses) and 12%, depending on strategy is to expose a narrow how much thermal mass will be strip about 8 ft. wide along the south wall next to the windows

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Ratio of Mass to Glass. The added for each 8.3 sf of thermal After that. the effectiveness simplest rule of thumb states: mass placed in the wall or doesn't increase as significantly. For each added ft2 of direct-gain . ceiling of the room. Mass in the A two-inch mass floor will be glass (above the 7% wall or ceiling does not have to about two-thirds as effective in a suntempering limit). 6 ft2 of be located directly in the direct gain system as a four­ exposed mass surlace should be sunlight. as long as it is in the inch mass floor. But a six-inch added within the direct-gain same room. with no other walls mass floor will only perform space. The following procedure between the mass and the area about eight percent better than can be used to determine a where the sunlight is falling. a four-inch floor. somewhat more accurate (The 8.3 value is typical. but the The effectiveness of thermal estimate. This procedure gives true value does depend on mass mass is relative to the density the maximum amount of direct­ density and thickness. Refer to and thickness. The vertical axis gain glazing for a given amount the mass thickness graph for shows how many square feet of of thermal mass. If the amount more specific values to use.) mass area are needed for each of direct-gain glazing to be used More south-facing glazing added square foot of direct gain. is already known. thermal mass than the maximum as As you can see. performance can be added until this determined here would tend to increases start leveling off after procedure produces the desired overheat the room. and to a few inches of thermal mass. proportions: reduce energy performance as 40 .2 • Start with a direct gain glass well. 50#/cf ,---..... ~ area equal to 7% of the house's / ...... / ...... ~ 30 total floor area. As noted above. / .... / ...... III / .... III 75#/cf the "free mass" in the house will / ...... ~ ~ 20 be able to accommodate this ~ .... ~ 100#/cf II, ...... :"' a. much solar energy. I, 01 I I 125#/cf I ~ 10 • An additional 1.0 sf of direct III 150#/cf gain glazing may be added for ~ every 5.5 sf of uncovered. sunlit 0 0 5 10 15 mass. Carpet or area rugs will Thickness (inches) seriously reduce the Mass Thickness effectiveness of the mass. The The effectiveness of thermal mass depends Mass Location and Effectiveness on the density of the material and thickness. maximum mass that can be Additional mass must be provided for south This graph is for wall or ceiling mass in the considered as "sunlit" may be . faCing glass over 7% of the floor area. The direct gain space. The ratio of 8.3 was used ratio of mass area to additional glass area earlier as a representative value. More estimated as about 1.5 times the depends on its location within the direct gain accurate values can be read from this graph south window area. space. and used in the fourth step of the procedure. • An additional 1.0 square foot of direct gain glazing may be Thickness. For most materials. In cases in which you are still added for every 40 sf of thermal the effectiveness of the thermal uncertain if thermal mass is mass in the floor of the room. mass in the floor or interior wall adequate. you can go to but not in the Sull. increases proportionally with Worksheet III: Thermal • An additional 1.0 square foot thickness up to about 4 inches. Mass/Comfort. which is more of direct gain glazing may be comprehensive.

Green Bay. Wisconsin 26 GUIDELINES PART THREE: STRATEGIES FOR IMPROVING ENERGY PERFORMANCE

Examples of Heat Energy Savings Passive Solar-Direct Gain 1,500 sf Single Story House

Base Case 20% 40% 60% R-values Ceiling/Roof 31 35 43- 56 Walls 19 22 27 35 Basement Wall 11 13 16 21 Glass 1.8 1.8 2.7 3.3

Air Changes/Hour 0.50 0.43 0.40 0.28

Glass Area (percent of total floor area) West 3.0% 2.0% 2.0% 2.0% North 3.0% 4.0% 4.0% 4.0% East 3.0% 4.0% 4.0% 4.0% South 3.0% 7.5% 9.2% 12.0%

Added Thermal Mass Percent of Floor Area 0.0% 3.1% 13.3% 30.0%

Solar System Size (square feet) South Glass 45 112 138 180 Added Thermal Mass 0 46 199 450

Percent Solar Savings 3% 11% 16% 23%

Performance (Btu/yr-sf) Conservation 52,730 47,239 37,492 27,791 Auxiliary Heat 50,890 41,713 31,505 21,255 Cooling 5,138 2,700 1,970 1,439

Summary: Insulation and tightness have been increased. South-facing glazing has been substantially increased. For these examples, added mass area is assumed to be six times the excess south glass area.

Green Bay, Wisconsin 4. Sunspaces The sunspace should not be The sunspace floor is a good on the same heating system as location for thermal mass.· The The sunspace is a very popular the rest of the house. A well mass floors should be dark in passive solar feature, adding an designed sunspace will probably color. No more than 15-250/0 of need no mechanical heating the floor slab should be covered attractive living space as well as system, but if necessary, a small with rugs or plants. The lower energy performance. There are fan or heater may be used to edge of the south-facing many variations on the basic protect plants on extremely cold windows should be no more theme of the sunspace, and the winter nights. than six inches from the floor to possibilities f«;>r sunspace design The sunspace should be just make sure the mass in the floor are extraordinarily diverse. As as tightly constructed and receives sufficient direct used in this guide, a sunspace insulated as the rest of the sunlight. If the windows sills is a separate direct-gain room are higher than that, additional on the south side of the house. house. The wall that separates the mass may have to be located in house from the sunspace is the walls. called a common wan. The Another good location for common wall should include thermal mass is the common operable windows and doors wall (the wall separating the that may be closed so that when sunspace from the rest of the the sunspace is not providing house). Options for the heat to the house it is not common wall are discussed in draining heat from the house. more detail later . The sunspace concept used Water in various types of in these Guidelines can be used containers is another form of energy storage often used in year-round, will provide most or Sunspaces all of its own energy needs, and Sunspaces provide useful passive solar sunspaces. heating and also provide a valuable amenity to will contribute to the energy homes. needs of the rest of the house as Glazing Clear. double-glazing is well. Thermal Mass recommended for sunspaces. Sunspaces are referred to as A sunspace has extensive Adding the second pane makes "isolated gain" passive solar south-faCing glass, so sufficient a l~ge improvement in energy systems, because the sunlight is thermal mass is very important. savings. Triple-glazing or low-e collected in an area which can Without it, the sunspace is coatings, on the other hand, will be closed off from the rest of the liable to be uncomfortably hot further improve comfort, but will house. During the day, the during the day. and too cold for have little effect on energy doors or windows between the plants or people at night. saVings. sunspace and the house can be However. the temperature in Windows on the east and opened to circulate collected the sunspace can vary more west walls should be small (no heat, and then closed at night, than in the house itself, so more than 100/0 of the total and the temperature in the about three square feet of four sunspace floor area) but they sunspace allowed to drop. It inch thick thermal mass for are useful for cross-ventilation. should be noted that the each square foot of sunspace common wall is often mass, and glazing should be adequate. not necessarily sufficient for the With this glass-to-mass ratio, on sunspace to be considered truly a clear winter day a temperature thermally isolated. swing of about 30°F should be expected.

Green Bay. Wisconsin 28 GUIDELINES PART THREE: STRATEGIES FOR IMPROVING ENERGY PERFORMANCE

Summer Overheating Common Wall Some solar energy may be Probably the single biggest There are a number of options transferred from the sunspace to problem encountered in for the sunspace common wall. the rest of the house by sunspaces is summer The common wall may be a conduction through the overheating. Largely, this stems masonry wall, it can also be common wall if it is made of directly from poor design used for thermal mass, in which thermal mass. But energy is practice and can be avoided. case it should be solid masonry mainly transferred by natural The problem can usually be approximately 4 to 8 inches convection through openings in traced directly to poor glazing thick. Another option is a frame the common wall - doors, orientations - too much non­ wall with masonry veneer. . windows and/or vents. south glazing. Glass on the roof In mild climates, and when • Doors are the most common or on the west walls can create the sunspace is very tightly opening in the common wall. If major overheating. constructed, an uninsulated only doorways are used, the Like tilted or sloped glazing, frame wall is probably adequate. open area should be at least glazed roofs can increase solar However, insulating the 15% of the sunspace south­ gain, but they can also present common wall to about R-10 is a glass area. big overheating problems and good idea, especially in cold • Windows or sliding glass become counter-productive. If climates. An insulated common doors will provide light and either glazed roofs or tilted wall will help guard against heat views. The window area in the glazing are used in the loss during prolonged cold, common wall should be no sunspace, special care should cloudy periods, or if the thermal larger than about 40% of the be taken to make sure they can storage in the sunspace is entire common wall area. Per be effectively shaded during the insufficient. unit. area, window and slider summer and, if necessary, on Probably the most important ?penings are about one-half as sunny days the rest of the year, factor in controlling the effective for natural convection too. The manufacturers of temperature in the sunspace, as are door openings. sunspaces and glazing are and thus keeping it as developing products with better comfortable and efficient as ability to control both heat loss possible, is to make sure the and heat gain (for example, roof exterior walls are tightly glazing with low shading constructed and well-insulated. coefficients, shading treatments and devices, etc.). You'll note that in the Performance Potential chart on page 6, sunspaces with glazed roofs or sloped glazing perform very well. This analysis assumes effective shading in the summer. If such shading is not economical or marketable in your area, you should consider using only vertical glazing, and accepting somewhat less energy performance in winter.

Green Bay. Wisconsin Summer ventilation The sunspace must be vented to Examples of Heat Energy Savings Passive Solar-Sunspace the outs~de to avoid overheating in the summer or on warm days 1,500 sf Single Story House in spring and fall. A properly vented and shaded sunspace Base Case 20% 40% 60% can function much like a R-Values screened-in porch in late spring. Ceiling/Roof 31 34 41 53 summer. and early fall. Walls 19 21 25 33 Operable windows and/or Basement Wall 11 12 15 19 Glass 1.8 1.8 1.8 3.3 vent openings should be located for effective cross-ventilation. Air Changes/Hour 0.50 0.47 0.29 0.29 and to take advantage of the prevailing summer wind. Low Glass Area (percent of total floor area) West 3.0% 2.0% 2.0% 2.0% inlets and high outlets can be North 3.0% 4.0% 4.0% 4.0% used in a "stack effect", since East 3.0% 4.0% 4.0% 4.0% warm air will rise. These South (windows) 3.0% 3.0% 3.0% 3.0% 0.0% ventilation areas should be at Sunspace 6.4% 8.9% 13.0% least 15% of the total sunspace Solar System Size (square feet) south glass areas. South Glass 45 45 45 45 Where natural ventilation is Sunspace Glass 0 96 132 195 insufficient, or access to natural Sunspace Thermal Mass 0 289 398 586 breezes is blocked. a small. Percent Solar Savings thermostat-controlled fan set at 3% 16% 21% 29% about 76°F will probably be a Performance (Btu/yr-sf) useful addition. Conservation 52,730 50,040 40,226 29,924 Auxiliary Heat 50,890 41,667 31,447 21,176 Cooling 5,138 3,005 2,298 1,754

Summary: Insulation and tightness have been increased. North and east­ facing glazing have been increased slightly. The sunspace assumed here is semi-enclosed (surrounded on three sides by conditioned rooms of the house, as in Figure SSD1 of the worksheets), with its south glazing tilted at 50 degrees. The common wall is a thermal mass wall made of masonry. Sunspace glazing is assumed to be double.

Green Bayt Wisconsin 30 GUIDELINES PART THREE: STRATEGIES FOR IMPROVING ENERGY PERFORMANCE

5. Thermal Storage Selective Surfaces A selective surface is a special Wall adhesive foil applied to the exterior side of the mass of The Thermal Storage Wall- also Thermal Storage Walls. referred to as a Trombe wall or Selective surfaces absorb a large an indirect gain system - is a percentage of solar radiation but south-facing glazed wall. usually radiate very little heat back to built of masonry. but sometimes the out-of-doors (low emittance). using water containers or phase Thermal Storage Wall To be effective. selective change materials. The masonry A thermal storage wall is an effective passive surfaces must be applied is separated from the glazing solar system, especially to provide nighttime heating. carefully for 100% adheSion to only by a air space. Sunlight is the mass surface. absorbed directly into the wall A masonry Thermal Storage Wall In Green Bay. Wisconsin. a instead of into the living space. should be solid. and there selective surface will improve The energy is then released into should be no openings or vents Thermal Storage Wall the living space over a relatively either to the outside or to the perfonnance by about 107%. long period. The time lag varies living space. Although vents to with different materials. the living space were once Mass Material and thicknesses and other factors. commonly built into Thennal Thickness but typically. energy stored in a Storage Walls. experience has In general. the effectiveness Thennal Storage Wall during the demonstrated that they are of the Thennal Storage Wall will day is released during the ineffective. Vents between the increase as the density of the evening and nighttime hours. Thermal Storage Wall and the material increases. The outside surface of a house tend to reduce the The optimum thickness of thermal storage wall should be a system's nighttime heating the wall depends on the density very dark color - an absorptance capability. and to increase the of the material chosen. but greater than 0.92 is temperature fluctuation in the performance is not very recommended .. house. Vents to the outside are sensitive to thickness. The The summer heat gain from similarly ineffective. and do little following chart indicates the a Thermal Storage Wall is much to reduce summer heat gains. recommended thickness of less - roughly 89% less - than Thermal Storage Walls made of from a comparable area of direct Glazing various materials. As thickness gain glazing. Double glazing is recommended is increased. the time delay of for Thennal Storage Walls. heat flow through the wall is unless a selective surface is increased. and the temperature used. In this case. single variation on the inside surface is glazing perfonns about the same decreased. as double glazing. The space between the glazing and the thermal mass .should be one to three inches.

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Mass Wall Thickness Examples of Heat Energy Savings Passive Solar-Thermal Storage Wall (inches) Density Thick- 1,500 sf Single Story House ness Material (Ib/cf) (inches) Base Case 20% 40% 60% R-Values Concrete 140 8-24 Ceiling/Roof 31 34 40 49 Concrete Masonry 130 7-18 Walls 19 21 25 31 Clay Brick 120 7-16 Basement Wall 11 12 15 18 Glass 1.8 1.8 1.8 2.7 Ltwt. Concrete 110 6-12 Masonry Air Changes/Hour 0.50 0.45 0.31 0.28 Adobe 100 6-12 Glass Area (percent of total floor area) West 3.0% 2.0% 2.0% 2.0% Water Walls North 3.0% 4.0% 4.0% 4.0% Water provides about twice the East 3.0% 4.0% 4.0% 4.0% heat storage per unit volume as South 3.0% 3.0% 3.0% 3.0% masonry. so a smaller volume of Thermal Storage Wall 0.0% 7.3% 11.1% 17.0% mass can be used. In "water Solar System Size (square feet) walls" the water is in light, rigid South Glass 45 45 45 45 containers. The containers are Thermal Storage Wall 0 109 166 255 shipped empty and easily Percent Solar Savings installed. Manufacturers can 3% 15% 23% 35% provide information about durability. installation. Performance (Btu/yr-sf) protection against leakage and Conservation 52,730 49,560 41,300 32,826 Auxiliary Heat 50,890 41,712 31,472 21,200 other characteristics. At least Cooling 5,138 2.312 1,368 566 30 pounds (3.5 gallons) of water should be provided for each Summary: In the case of a Thermal Storage Wall, south-facing glazing square foot of glazing. This is and thermal mass are incorporated together. The estimates here assume a 12-inch thick concrete Thermal Storage Wall with a selective surface equivalent to a water container and single glazing. about six inches thick. having the same area as the glazing.

Green Bay, Wisconsin 32 GUIDELINES PART THREE: STRATEGIES FOR IMPROVING ENERGY PERFORMANCE

6. Combined Systems 7. Natural Cooling Fortunately. many of the features that help maintain Guidelines Although the previous sections comfort and reduce energy needs in winter also work well in have presented separate The term "natural cooling" is summer. For instance. discussions of four different used here to describe systems. it isn't necessary to additional thermal mass techniques which help a house performs well year-round. choose one and only one stay cool in summer but which Masonry materials are equally system. In fact. passive solar require little or no energy. effective in staying cool and features work well in Natural cooling techniques work storing heat. lf mass surfaces combination. to help reduce air-conditioning. can be exposed to cool night­ For example. direct gain not replace it. time temperatures - a technique works very well in conjunction These techniques are useful referred to as "night ventilation" with a sunspace or thermal not only in passive solar houses. - they will help the house stay storage wall. Since thermal but in "conventional" houses as cooler the next day. A California storage walls release energy well. The strategies outlined utility found during studies of more slowly than direct gain below - attention to the location. small test buildings that on hot systems. they are useful for size and shading of glazing. summer days the workmen at supplying heat in the evening using the opportunities on the the facility always ate lunch in and at night. whereas the direct site for shading and natural the masonry test building gain system works best during ventilation. and using fans - can because it stayed much cooler the day. Although using a reduce air conditioning needs than any of the others. sunspace. thermal storage wall and increase comfort even if the The additional insulation and direct gain system in the house has no passive solar that increases winter same house may result in heating features. performance will also work to excellent performance. such But shading is particularly improve summer performance combinations do require a large important in passive solar by conserving the conditioned south-facing area. and careful houses. because the same air inside the house. And some design to make sure the systems features that collect sunlight so low-e windows and other glazing are well-integrated with each effectively in winter will go right with high R-value can help other and with the house's on collecting it in summer - shield against unwanted heat mechanical system. resulting in uncomfortably hot gain in summer. rooms and big air conditioning bills - unless they are shaded and the house is designed to help cool itself.

Green Bav. Wisconsin The potential of some Cooling Potential natural and low-energy cooling Basecase 5,138 Btu/yr-sf strategies is shown in the following table for Green Bay. Energy Savings Percent Worksheet IV: Cooting Strategy (Btu/yr-sf) Savings Performance Level indicates the total annual cooling load, No Night Ventilation 1 0 0% and so can give an idea of how without ceiling fans with ceiling fans 1,740 34% the passive solar features increase the cooling load and Night Ventilation1 how much reduction is possible without ceiling fans 930 18% with ceiling fans 2,540 49% when natural cooling techniques are used. High Mass2 It should be noted that the without ceiling fans 420 8% Cooling Performance numbers with ceiling fans 380 7% presented in the Examples for 1 With night ventilation, the house is ventilated at night when each passive solar strategy temperature and humidity conditions are favorable. assume that the design also includes the recommended 2 A "high mass" building is one with a thermal mass area at least equal to the house floor area. natural cooling techniques. This is especially true of the higher percentage reductions: these assume better heating performance, but also better shading and other natural cooling strategies.

Green Bay. Wisconsin 34 GUIDELINES PART THREE: STRATEGIES FOR IMPROVING ENERGY PERFORMANCE

Glazing and so they may interfere with As mentioned earlier, poorly Added Window Cooling Load desirable views. It is important placed windows can increase air to note, however, that some conditioning loads dramatically. Added Annual types of low-e windows' block Cooling It is generally best in terms of solar transmission but also Orientation Load(Btu/yr-sf) energy performance to carefully allow clear views. These size non-solar glazing as treatments are not North 19,790 indicated in the following table. recommended for south East 39,190 windows. South 31,930 Recommended Non-south Glass As the table shows, skylights West 43,800 Guidelines present a high potential for Skylights 65,500 Percent of Total overheating, and are usually difficult to shade properly. But Orientation Floor Area These values are based on double skylights are very popular glass with a shading coefficient of features, and they save East 4% 0.88. When glazing with a different electricity by providing good North 4% shading coefficient is used the natural daylight to the house. West 2% values may be scaled In some parts of the country proportionally. almost every new house has at West-facing windows present least one skylight. A good These numbers can be reduced particularly difficult shading working compromise can by shading as described in the problems. If glazing is added usually be achieved if skylight next section. above the levels indicated, the area is limited, and if careful Using special glazing or need for shading will become attention is paid to shading, window films that block solar even more critical. either by trees or by devices transmission (low shading Cooling loads increase as such as roller shades or blinds. coeffiCient) is an option often window area increases. This The manufacturer can usually used in particularly hot relationship for Green Bay is give guidance on shading climates, but the more effective shown in the following table for options for a particular skylight they are at blocking sunlight, each of the cardinal window design. the less clear they are, as a rule, orientations. For instance when a square foot of west area is added or subtracted, the annual cooling load increases or decreases by 43,800 Btu/yr-sf.

Green Bay, Wisconsin Shading Roof Overhangs. Fixed Shading strategies generally fall overhangs are an inexpensive into three categories: feature. and require no landscaping. roof overhangs and operation by the home owner. exterior or interior shading They must be carefully devices. designed. however. Otherwise. an overhang that blocks Landscaping. The ideal site for Landscaping for Summer Shade summer sun may also block sun summer shading has deCiduous Trees and other landscaping features may be in the spring. when solar effectively used to shade east and west trees to shade the east and west windows from summer solar gains. heating is deSired. and. by the windows. Even small trees such same token. an overhang sized as fruit trees can help block sun Other landscaping ideas for for maximum solar gain in hitting the first story of a house.' summer shade: winter will allow solar gain in Trees on the south side can • Trellises on east and west the fall on hot days. The present a difficult choice. Even covered with vines. following figure may be used to deciduous trees will shadow the • Shrubbery or other plantings determine the optimum solar glazing during the winter to shade paved areas. overhang size. and interfere with solar gain. In • Use of ground cover to In Green Bay. an ideal fact. trees on the south side can prevent glare and heat overhang projection for a four all but eliminate passive solar absorption. foot high window would be 31 performance. unless they are • Trees. fences. shrubbery or inches and the bottom of the v~ry close to the house and the other plantings to "channel" overhang would be 15 inches low branches can be removed. summer breezes into the house. above the top of the window. allowing the winter sun to • Deciduous trees on the east penetrate under the tree canopy. and west sides of the house. as A However. in many cases the shown above. to balance solar trees around the house are gains in all seasons. bigger selling points than the energy efficiency and the builder must make a choice. If a careful study of the shading patterns is done before construction. it should be possible to accomodate the south-facing glazing while South Overhang Sizing In Green Bay, an ideally sized south overhang leaving in as many trees as should allow full exposure of the window when possible (see page 17. Site the sun has a noon altitude of 27 degrees Planning for Solar Access). (angle A) and fully shade the window when the sun has a noon altitude of 64 degrees (angle B).

Green Bay. Wisconsin 36 GUIDELINES PART THREE: STRATEGIES FOR IMPROVING ENERGY PERFORMANCE

A combination of carefully sized Ceiling Fans overhangs on the south Ceiling fans will probably save Ceiling Fan Sizes windows and shading devices on more energy than any other Largest Room Minimum Fan the other windows will probably single cooling strategy. Studies Dimension Diameter be an effective solution. show that air movement can (inches) Adjustable overhangs that can make people feel comfortable at be seasonally regulated are higher temperatures. As a 12 feet or less 36 another option. general rule. the thermostat can 12 -16 feet 48 be set 4 degrees higher without 16 - 17.5 feet 52 Shading Devices. External affecting comfort if the air is 17.5 - 18.5 feet 56 shades are the most effective moving at 100-150 feet per 18.5 or more feet 2 fans because they stop solar gain minute. This is enough air before the sun hits the building. movement to greatly improve A ceiling fan should have a A wide range of products are comfort but not enough to minimum clearance of ten aVailable. from canvas awnings disturb loose papers. inches between ceiling and fan to solar screens to roll-down to provide adequate ventilation blinds to shutters to vertical in a standard room with eight­ louvers. They are adjustable foot ceilings. In rooms with and perform very well. but their higher ceilings. fans should be limitation is that they require mounted 7.5 to 8.0 feet above the home owner's cooperation. the floor. Usually external screens that can be put up and taken down once a year like storm windows are more acceptable to home owners than those requiring more frequent operation. Interior shades must be operated. too. and have the further disadvantage of permitting the sun to enter the house and be trapped between the window and the shading device. But highly reflective interior blinds and curtains are relatively low-cost and easy to operate. Another shading "device" well worth considering is a porch. Especially on the east and west sides. porches add pleasant spaces to houses and are excellent for providing shade to windows. Carports located on the east or west are another option.

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Ventilation The best possible When possible. the house performance of a whole-house should be positioned on the site fan results when a timer. a to take advantage of prevailing thermostat and a "humidistat" winds. The prevailing wind are used. so that the fan would direction is from the south west only operate when there is less during the cooling season. than 60% relative hUmidity and Windows. stairwells. transoms a temperature of less than 76°F. and other elements should be Natural ventilation and located for maximum cross­ Ventilation for Summer Cooling whole-house fans are effective at Natural ventilation is often impaired by ventilation in each room. The vegetation and topography. Ventilation fans removing heat. but not at free vent area (unobstructed do not depend !,n surroundings to be effective. moving air. Ceiling fans. on the openings like open windows) other hand. can often create should be between 6-7.5% of In cooling climates. a whole­ enough of a breeze to maintain total floor area, half located on house fan is a good idea for comfort at higher temperatures. the leeward and half on the assisting ventilation. especially and still use less power than windward side of the building. in houses with sites or designs required by air conditioning. By Insect screens can reduce the that make natural ventilation using natural cooling strategies effective free vent area by as difficult. On the other hand. and low-energy fans. the days much as 50%. Casement or when the temperature is higher when air-conditioning is needed awning windows have a 90% than about 76°F. a whole-house can be reduced substantially. open area; double hung fan will not be very effective. windows have only 50%. Research indicates that a Casement windows extend whole-house fan should pull outward from the house. apprOximately 10 ACH. A rule tending to channel breezes of thumb: for rooms with eight through the opening if properly foot ceilings. total floor area placed. Improperly placed multiplied by 1.34 will equal the casements might deflect breezes. necessary CFM of the fan. For Double-hung windows do not 10 foot ceilings. multiply floor have this advantage. area by 1.67. Natural ventilation can help keep houses cool and comfortable at the beginning and end of the cooling season and thus shorten the time when air conditioning is required. But natural ventilation can seldom do the entire cooling job. especially for less than ideal sites with little natural air movement.

Green Bay. Wisconsin 38 GUIDELINES PART THREE: STRATEGIES FOR IMPROVING ENERGY PERFORMANCE

Green Bay. Wisconsin Passive Solar Design Strategies WORKSHEETS

......

...; .. ; .... ; .. ; .. ;.... ; .. ; ......

Passive Solar Industries COWlcil National Renewable Energy Laboratory Charles Eley Associates With Support From: U.S. Department of Energy PASSIVE SOLAR DESIGN STRATEGIES 39

NOTE: Please make copies of the blank worksheets and tables before entering numbers so that the worksheets may be used to evaluate several design options.

Green Bay, Worksheets Wisconsin 4U PASSIVE SOLAR DESIGN STRATEGIES General Pro' ect Information

Project Name Floor Area ~------~------Desjgner

Worksheet I: Conservation Performance Level

A. Envelope Heat Loss

Construction R-value Heat Description Area [Table A] Loss

Q!liliC9lll[QQt~

~

IOllUI51!!lrJ EIQQ[ll

~QC-llQI51[ ~15lZiCg

.P.Qw.

Btu/oF-h Tolal B. Foundation Perimeter Heat Loss Heat Loss Factor Heat Description Perimeter [Table B] Loss

~151bll-QC-~[51rJ!l X t:J!l51!!lrJ 65111!lID!lO!1l X UCb!l51!!lrJ El5!ll!lID!lC!~ X E!l[ilD!l!!l[ IOllUI51!!lrJ Q[srlillll25lQ!lll X Btu/oF-h Total

C. Infiltration Heat Loss X X .018 Btu/OF-h Building Air Changes Volume per Hour

D. Total Heat Loss per Square Foot 24 X Btu/DO-sf Tolal Heat Loss Floor Area (A+B+C)

E. Conservation Performance Level

x X Btu/yr-sf Total Heat Heating Degree Heating Degree Loss per Days [Table C] Day Multiplier Square Foot [Table C]

F. Comparison Conservation Performance (From PrevIous Calculation or from Table D) Btu/yr-sf Com are Line E to Line F

Green Bay, Wisconsin PASSIVE SOLAR DESIGN STRATEGIES 41 Worksheet II: A1Irili Heat Performance Level A. Projected Area of Passive Solar Glazing Solar System Rough Frame Net Area Adjustment Projected Reference Code Area Factor Factor [Table E] Area X 0.80 X X 0.80 X X 0.80 X = X 0.80 X = X 0.80 X = X 0.80 X = X 0.80 X = sf Total Area Total Projected Area

+ = Total Floor Total Projected Projected Area Area per Area Square Foot

B. Load Collector Ratio 24 X + = Total Total Heat Loss Projected [Worksheet I] Area

C. Solar Savings Fraction System Solar Savings Solar System Projected Fraction Reference Code Area [Table F] X = X = X = X = X X X

+ Total Total Solar Projected Savings Area Fraction

D. Auxiliary Heat Performance Level

[1 - X = Btu/yr-sf Solar Conservation Savings Performance Fraction Level [Worksheet I, Step E]

E. Comparative Auxiliary Heat Performance (From Previous Calculation or from Table G) Btu/yr-sf Compare UneDto LmeE

Green Bay, W1scoDSiD 42 PASSIVE SOLAR DESIGN STRATEGIES Worksheet III: Thermal Mass/Comfort A. Heat Capacity of Sheetrock and Interior Furnishings Unit Total Heat Heat Floor Area Capacity Capacity Rooms with Direct Gajn X 4.7 SPaceS Connected to Direct Gajn SPaces ______X 4.5 Btu/OF Total B. Heat Capacity of Mass Surfaces Enclosing Direct Gain Spaces Unit Heat Mass Description Capacity Total Heat (include thickness) Area rrable H) Capacity Trombe Walls X 8.8

~rwwls ______X 10.4 = ExPOsed Slab in Syn ______X 13.4 Exposed Slab Not in Syn X 1.8 = X = X = X = Btu/OF Total

C. Heat Capacity of Mass Surfaces Enclosing Spaces Connected to Direct Gain Spaces Unit Heat Mass DeSCription c~acity Total Heat (include thickness) Area [T Ie H) Capacity IrQmbi WWlli X 3.8 Wate[wwlli X 4.2 X = X = X = Btu/OF Total

D. Total Heat Capacity Btu/OF (A+B+C)

E. Total Heat Capacity per Square Foot + Btu/OF-sf Total Heat Conditioned Capacity Roor Area

F. Clear Winter Day Temperature Swing Total Comfort Projected Area Factor [Worksheet II] rrable I] Di[ect Gajn X

SynliPaceli Q[ X = Vented Trombi WWlli + Total Total Heat Capacity G. Recommended Maximum Temperature Swing OF Compare Line F to Line G

~ ____ D__ ftft ____ -.l_ PASSIVE SOLAR DESIGN STRATEGIES 43 Worksheet IV: Summer Coolin Performance Level A. Opaque Surfaces Radiant Barrier Absorp- Heat Gain Heat Loss Factor tance Factor Description [Worksheet I] [Table J) [Table K] [Table L] Load

Ceilings/roofs X X X = X X X X X X ~ X na X X na X QQw. X na X kBtulyr Total B. Non-solar Glazing Rough Frame Net Area Shade Factor Heat Gain Description Area Factor [Table M] Factor [Table L] Load

North Glass X 0.80 X X = X 0.80 X X East Glass X 0.80 X X X 0.80 X X ltiiat !:alaaa X 0.80 X X = X 0.80 X X Slsllligbta X 0.80 X X = X 0.80 X X = kBtulyr Total C. Solar Glazing Solar System Rough Frame Net Area Shade Factor Heat Gain Description Area Factor [Table M] Factor [Table L] Load

Qi[i!Bedrooms [Table N] [Table N] E. Cooling Load per Square Foot 1,000 X + = Btu/yr-sf (A+B+C+D) Floor Area F. Adjustment for Thermal Mass and Ventilation Btu/yr-sf [Table 0] G. Cooling Performance Level Btu/yr-sf (E-F) H. Comparison Cooling Performance (From Previous Calculation or from Table P) Btu/yr-sf Compare Lme Gto LmeH

Green Bay. WlscolUdn 44 PASSIVE SOLAR DESIGN STRATEGIES

Table A-continued •• Table A-Eqaivalent Thermal Performance of AsaembUes Table D-Base Case R-values (hr-F-sf/Btu) Conservation Performance (Btu/yr­ As-Doors sf) Solid wood w~h 2.2 Base Case 52,730 Weatherstripping A1-CeilingsIRoofs Metal with rigid 5.9 Attic Insulation R-value foam core Table E-Projected Area Construction R-30 R-38 R-49 R-6O Adjustment Factors 27.9 35.9 46.9 57.9 Degrees off Solar System Type Framed Insulation R-value Table B-Perimeter Heat Lo.. True DG, TW, SSA SSB, Construction R-19 R-22 R-30 R-38 Factors for Slabs-on-Grade and South WW, SSC SSD SSE Unheated Basements (Btu/h-F-ft) o 1.00 0.77 0.75 2x6 at 16'oc 14.7 15.8 16.3 5 1.00 0.76 0.75 2x6 at 24'oc 15.3 16.5 17.1 Heated Unheated Insulated 10 0.98 0.75 0.74 2x8 at 16'oc 17.0 18.9 20.6 21.1 Perimeter Siabs-on· Base- Base- Crawl- 15 0.97 0.74 0.73 2x8 at 24'oc 17.6 19.6 21.6 22.2 Insulation Grade ments ments spaces 20 0.94 0.72 0.70 2xl0atl6'oc 18.1 20.1 24.5 25.7 None 0.8 1.3 1.1 1.1 25 0.91 0.69 0.68 2xl0 at 24'oc 18.4 20.7 25.5 26.8 R-5 0.4 0.8 0.7 0.6 30 0.87 0.66 0.65 2x12 at 16'oc 18.8 21.0 25.5 30.1 R-7 0.3 0.7 0.6 0.5 2x12 at 24 'oc 19.0 21.4 27.3 31.4 R·ll 0.3 0.6 0.5 0.4 R-19 0.2 0.4 0.5 0.3 Table F-Soiar System Saving R-30 0.1 0.3 0.4 0.2 Fractions A2-framed Walls Single F1-{)irect Gain Wall Insulation R-value Table C-Heating Degree Days Framing R-ll R-13 R-19 R-25 (F-day) Load DGCl DGC2 DGC3 2x4 at 16'oc 12.0 13.6 Collector Double Low-e R-9 Night 2x4 at 24'oc 12.7 13.9 Ratio Glazing Glazing Insulation 2x6 at 16'oc 14.1 15.4 17.7 19.2 C1-Heating Degree Days (Base 65°F) 400 0.02 0.03 0.04 2x6 at 24'oc 14.3 15.6 18.2 19.8 300 0.03 0.04 0.05 Green Bay 8,143 200 0.04 0.05 0.07 Double Antigo 8,624 150 0.05 0.07 0.09 Wall Total Thickness (inches) Appleton 7,728 100 0.06 0.10 0.13 Framing 8 10 12 14 80 0.07 0.11 0.16 Menominee 7,913 25.0 31.3 37.5 43.8 60 0.09 0.14 0.20 New London 7,n8 50 0.10 0.16 0.23 Octonto 8,024 45 0.11 0.18 0.25 The R-value of insulating sheathing should be added to Oshkosh 7,692 40 0.11 0.19 0.27 the values in this table. 35 0.12 0.21 0.30 Roshott 8,328 30 0.13 0.23 0.34 Shawano 7,953 25 0.14 0.26 0.38 A3-Insulated Floors Stevens Point 8,107 20 0.14 0.30 0.44 Sturgeon Bay 7,898 15 0.15 0.35 0.52 Insulation R-value Framing R-ll R-19 R-30 R-38 Two Rivers 7,802 Waupaca 7,724 2x6s at 16'oc 18.2 23.8 29.9 F2-Trombe Walls 2x6s at 24'oc 18.4 24.5 31.5 Wasau AP 8,565 TWF3 TWA3 TWJ2 TWI4 2x8s at 16'oc 18.8 24.9 31.7 36.0 Load Unvented Vented Unvenled Unvented 2xBs at 24 'oc 18.9 25.4 33.1 37.9 Collector Non- Non- Selec- Night 2xl0 at 16'oc 19.3 25.8 33.4 38.1 C2-Heating Degree Day Multiplier Ratio selective selective live Insulation 2xl0 at 24 'oc 19.3 26.1 34.4 39.8 Passive Solar 400 0.01 0.03 0.00 0.00 2x12 at 16'oc 19.7 26.5 34.7 39.8 Heat Loss Glazing Area per 300 0.01 0.04 0.01 0.00 2x12 at 24 'oc 19.6 26.7 35.5 41.2 per Square per Square Foot 200 0.03 0.05 0.04 0.01 Foot .00 .05 .10 .15 .20 150 0.04 0.06 0.07 0.04 These R-values include the buffering effect of a 100 0.06 0.09 0.12 0.08 ventilated crawlspace or uncond~ioned basement. 12.00 1.07 1.08 1.08 1.08 1.09 11.50 1.07 1.07 1.08 1.08 1.08 80 0.07 0.10 0.15 0.11 11.00 1.06 1.07 1.07 1.07 1.08 60 0.09 0.12 0.20 0.15 10.50 1.06 1.06 1.07 1.07 1.07 50 Qll Q14 Q24 Q19 A4-Windows 10.00 1.05 1.06 1.06 1.06 1.07 45 0.12 0.15 0.26 0.21 40 0.13 0.16 0.29 0.23 Air Gap 9.50 1.04 1.05 1.05 1.06 1.06 9.00 1.04 1.04 1.05 1.05 1.06 35 0.14 0.17 0.32 0.26 30 0.16 0.19 0.35 0.29 1/4 in. 1/2 in. 1/2 in. argon 8.50 1.03 1.03 1.04 1.04 1.05 8.00 1.02 1.03 1.03 1.04 1.04 25 0.18 0.21 0.40 0.34 Standard Metal Frame 7.50 1.01 1.02 1.02 1.03 1.04 20 0.20 0.23 0.46 0.39 Single .9 7.00 0.99 1.00 1.01 1.02 1.03 15 0.23 0.26 0.54 0.47 Double 1.1 1.2 1.2 6.50 0.98 0.99 1.00 1.01 1.02 Low-e (e<:O.40) 1.2 1.3 1.3 6.00 0.96 0.98 0.99 1.00 1.01 Metal frame with thermal break 5.50 0.94 0.96 0.97 0.98 0.99 Double 1.5 1.6 1.7 5.00 0.92 0.93 0.95 0.97 0.98 Low-e (e<:O.40) 1.6 1.8 1.8 4.50 0.89 0.91 0.93 0.94 0.96 Low-e (e<:020) 1.7 1.9 2.0 4.00 0.86 0.88 0.90 0.92 0.94 Wood frame with vinyl cladding 3.50 0.81 0.85 0.87 0.89 0.91 Double 2.0 2.1 2.2 3.00 0.76 0.80 0.83 0.86 0.88 Low-e (e<:O.40) 2.1 2.4 2.5 2.50 0.69 0.74 0.78 0.82 0.85 Low-e (e<:020) 2.2 2.6 2.7 2.00 0.58 0.66 0.72 o.n 0.81 Low-e (9<:0.1 0) 2.3 2.6 2.9 These R-values are based on a 3 mph wind speed and are typical for the entire rough framed opening. Manufacture's data, based on National Fenestration Rating Council procedures, should be used when available. One half the R-value of movable insulation should be added, when appropriate.

Green Bav. ~co~ F3-Water Walls Table H-Unit Heat Capacities Table lr-Heat Gain Factors (Btu/F-sf) Ceilinglroofs 27.3 Load WWA3 WWB4 WWC2 Watls and Doors 11.8 CoUector No Night Night Selectiv& North Glass 19.8 Ratio Insulation Insulation Surface H1-Mass Surfaces Enclosing Direct Gain Spaces East Glass 39.2 400 0.02 0.00 0.00 West Glass 43.8 300 0.02 0.00 0.00 Skylights 65.5 200 0.04 0.02 0.03 Thickness (inches) Direct Gain Glazing 31.9 150 0.06 0.05 0.05 Material 1 2 3 4 6 8 12 Trombe Walls and 3.4 100 0.08 0.10 0.10 Poured Conc. 1.8 4.3 6.7 8.8 11.3 11.5 10.3 Water Walls 80 0.10 0.14 0.14 Conc. Masonry 1.8 4.2 6.5 8.4 10.2 10.0 9.0 Sunspaces 60 0.12 0.19 0.19 Face Brick 2.0 4.7 7.1 9.0 10.4 9.9 9.0 SSAl 12.8 50 0.14 0.23 0.22 Flag Stone 2.1 4.8 7.1 8.5 8.6 8.0 7.6 SSBI 12.8 45 0.15 0.26 0.25 Builder Brick 1.5 3.7 5.4 6.5 6.6 6.0 5.8 SSC1 3.4 40 0.16 0.28 0.27 Adobe 1.3 3.2 4.8 5.5 5.4 4.9 4.8 SSDI 12.8 35 0.18 0.32 0.30 Hardwood 0.4 1.4 1.8 1.7 1.5 1.5 1.5 .. SSEI 12.8 30 0.19 0.36 0.34 Water 5.2 10.4 15.620.831.2 41.662.4 25 0.21 0.41 0.38 20 0.24 0.47 0.44 15 0.27 0.55 0.52 H2-Rooms with no Direct Solar Gain Table M-Sbading Factors F4-Sunspaces Projection Thickness (inches) Factor South East North West Load Material 1 2 3 4 6 8 12 0.00 1.00 1.00 1.00 1.00 Collector Sunspace Type Poured Conc. 1.7 3.0 3.6 3.8 3.7 3.6 3.4 0.20 0.85 0.97 0.94 0.97 Ratio SSAl SSBl SSCl SSDl SSEl Cone. Masonry 1.6 2.9 3.5 3.6 3.6 3.4 3.2 0.40 0.44 0.85 0.84 0.85 400 0.08 0.06 0.02 0.06 0.04 Face Brick 1.8 3.1 3.6 3.7 3.5 3.4 3.2 0.60 0.28 0.56 0.69 0.58 r:)...... ,1"1 '.,,''''',,) 0.08 0.07 0.02 0.07 0.05 Flag Stone 1.9 3.1 3.4 3.4 3.2 3.1 3.0 0.80 0.19 0.45 0.45 0.46 200 0.10 0.00 0.04 0.09 0.07 Builder Brick 1.4 2.6 3.0 3.1 2.9 2.7 2.7 1.00 0.10 0.36 0.36 0.36 150 0.12 0.09 0.05 0.11 0.08 Adobe 1.2 2.4 2.8 2.8 2.6 2.4 2.4 1.20 0.04 0.26 0.27 0.27 100 0.14 0.11 0.07 0.14 0.11 Hardwood 0.5 1.1 1.3 1.2 1.1 1.0 1.1 EJ 0.16 0.13 0.08 0.16 0.12 Muniply by 0.8 for low-e glass, 0.7 for tinted glass and 60 0.18 0.15 0.10 0.19 0.15 0.6 for iow-e tinted glass. 5Q 0.20 0.16 0.12 0.21 0.16 45 0.21 0.17 0.12 0.22 0.17 Table I-Comfort Factors 40 0.22 0.18 0.13 0.24 0.18 (Btu/sf) Table N-Intemal Gain Factors 35 0.23 0.19 0.14 0.25 0.19 .:;,; 0.25 0.21 0.16 0.27 0.20 Direct Gain 780 25 0.26 0.22 0.17 0.29 0.22 Constant Component 1,000 2C 0.29 0.24 0.19 0.32 0.23 Suns paces and 260 kBtuiyr 15 0.32 0.27 0.21 0.35 0.25 Vented Trombe Walls Variable Component 420 kBtuiyr-BR

Table J-Radiant Barrier Factors Table 0-Thermal Mass and Ventilation Adjustment (Btu/yr-sf) Radiant Barrier 0.75 Total Heat Night Night No Night No Night No Radiant Barrier 1.00 Capacity Vent wi Vent wi No Vent wi Vent wi No per SF Ceil. Fan Ceil. Fan Ceil. Fan Ceil. Fan 0.0 2,330 510 1,520 -420 1.0 3.110 1,430 2,310 500 Table K-Solar Absorptances 2.0 3.570 1,960 2.770 1,030 3.0 3,840 2,280 3,040 1,340 Color Absorptance 4.0 4,000 2,460 3,200 1,530 5.0 4,100 2,560 3,300 1,630 Gloss Whrte 0.25 6.0 4,150 2,630 3.350 1,700 Semi-gloss Whrte 0.30 7.0 4,190 2,660 3.380 1,730 Light Green 0.47 8.0 4,210 2,680 3,400 1,750 Kelly Green 0.51 9.0 4,220 2,690 3,410 1,760 Medium Blue 0.51 10.0 4,220 2,700 3,420 1,770 Medium Yellow 0.57 Medium Orange 0.58 Total heat capacrty per square foot is calculated on Medium Green 0.59 Worksheet III, Step E. Licht Buff Brick 0.60 Bare Concrete 0.65 Red Brick 0.70 Medium Red 0.80 Medium Brown 0.84 Table P-Base Case Cooling Performance (Btu/sf-yr) Table G-Base Case Auxiliary Dark Blue-Grey 0.88 Dark Brown 0.88 Heat Performance (Btu/yr-sf) Base Case 5,138

Base Case 50,890

Green Bay. Wisconsin 46 PASSIVE SOLAR DESIGN STRATEGIES

General on Worksheet I. Step D and Worksheet II, An exposed slab is one finished with The Worksheets provide a Step A. vinyl tile. ceramic tile or other highly calculation procedure to estimate the Should the estimated conservation conductive materials. Carpeted slabs performance level of passive solar performance level be greater than should not be considered exposed. The building designs. It is recommended desired. the designer should consider exposed slab area should be further that the results be compared to additional building insulation or reduced by about 50 percent to account Worksheet calculations for the builder's reducing non-south glass area. for throw rugs and furnishings. typical house. Performance levels for the As a rule-of-thumb. exposed slab NAHB Base Case House used in the Worksheet n-Auziliary Heat area should be considered to be in the Performance Level Guidelines are also provided for sun only when it is located directly This is an estimate of the amount of comparison. A separate worksheet is behind south glazing. The maximum heat that must be provided each year provided for the four separate slab area that is assumed to be in the from the auxiliary heating system. It performance levels and associated base sun should not exceed 1.5 times the accounts for savings due to solar energy. cases. adjacent south glass area. In Step A ,the user may enter the The worksheets are supported by a In Step F. the projected area of solar rough frame area of solar glazing. since number of data tables. The tables are glazing calculated on Worksheet II is it is generally easier to measure the given a letter designation and are used to calculate the comfort rough frame area than it is the net referenced next to each worksheet entry. performance level. The projected area of glazing area. The worksheet includes a when applicable. water walls and unvented Trombe walls net area factor of 0.80 to account for The floor area used in the is excluded in this step. window frames and mullions. If the calculations should not include A high temperature swing indicates designer enters the net glass area. then sunspaces, garages or other inadequate thermal mass or too much the net area factor is 1.00. unconditioned spaces. direct gain solar glazing. If the comfort The projected area of the solar performance level is greater than desired Worksheet I-Conservation energy systems may be calculated using (13°F recommended). additional thermal Performance Level the adjustment factors in Table E or by mass should be added to the building or This is an estimate of the amount of making a scaled elevation drawing of the direct gain glazing should be reduced. heat energy needed by the building each building facing exactly south and year from both the solar system and the measuring the glazing area from the Worksheet IV-Swnmer Cooling auxiliary heating system. scaled drawing. Performance Level For Step A. it is necessary to The projected area per square foot is This is an estimate of the annual cooling measure the net area of surfaces that calculated as the last part of Step A. load of the building-the heat that needs enclose conditioned space. For walls, This is used to determine the heating to be removed from the building by an the net surface area is the gross wall degree days adjustment used on air conditioner in order to maintain area less the window and door area. Worksheet I, Step E. comfort during the summer. Rough frame dimensions are The load collector ratio is calculated In Step A. only the envelope generally used to measure window area. in Step B. This is used to determine the surfaces that are exposed to sunlight are The R-values in Table A4 are for the solar savings fractions in Step C. to be included. For instance. floors over rough frame window area. The solar energy systems used in crawlspaces and walls or doors adjacent Heat loss from passive solar Step C should be identical to those used to garages are excluded. systems is excluded. The surface area of in Step A. The first and last columns of Steps B and C of the worksheet direct gain glazing, Trombe walls. water Step A are simply carried down. account for solar gains. They use the walls and the walls that separate The solar savings fraction is rough frame area since this is easier to sunspaces from the house are ignored. determined separately for each type of measure. The worksheets include a net Step A includes consideration of passive solar system by looking up area factor of 0.80 to account for window insulated floors over crawlspaces. values in Tables Fl through F4. The frames and mullions. If the net window unheated basements or garages. sunspace system types are shown area is used. the net area factor is 1.00. R-values are prOvided in Table A3 that beneath Table F4. Table M gives the shade factor for account for the buffering effect of these If the auxiliary heat performance windows with overhangs based on a unconditioned spaces. When insulation level calculated in Step D is larger than projection factor. The projection factor is not installed in the floor assembly, but desired, the designer should consider is the ratio between the horizontal rather around the perimeter of a increasing the size of the solar energy projection of the overhang from the crawlspace or unheated basement. Step systems or adding additional solar surface of window and the distance from B should be used. energy systems. i.e. thermal storage the bottom of the window to the bottom The perimeter method of Step B is walls. of the overhang. When windows have used for slabs-on-grade. the below-grade sunscreens. tints or films, the shade Worksheet m-Comfort portion of heated basements, unheated factors in Table M should not be used. Performance Level basements (when the floor is not Instead, a shading coefficient should be This is the temperature swing expected insulated), and perimeter insulated determined from manufacturers' on a clear winter day with the auxiliary crawlspaces (when the floor is not heating system not operating. insulated). Heated basement walls that This worksheet requires that two are above grade should be considered in sub-areas be defined within the building: Step A. those areas that receive direct solar Slab edge perimeter. unheated gains and those areas that are basements or perimeter insulated connected to rooms that receive direct crawlspaces adjacent to sunspaces B Projection = A solar gains. Rooms that are separated Factor B should not be included. from direct gain spaces by more than The conservation performance level one door should not be included in is calculated as the product of the heat either category. loss per degree day per square foot (Step Thermal mass elements located in If the cooling perlormance level is DI and the heating degree days. adjusted unconditioned spaces such as sunspaces for the heat loss and solar glazing per greater than desired. the designer are not included. square foot. The adjustment is taken should consider reducing non-south from Table C. based on data calculated glass. providing additional shading or ~.AAft RQ'U' moia,..ftftaoi", Passive Solar Design Strategies EXAMPLE

...: .. :.... :.. : ...... : .. : ......

Passive Solar Industries Council National Renewable Energy Laboratory Charles Eley Associates With Support From: U.S. Department of Energy PASSIVE SOLAR DESIGN STRATEGIES 47

Green Bay, The Worked Wisconsin Exam.ple 48 WORKED EXAMPLE

The Worked Example The house has a semi­ The house is equipped with enclosed sunspace with glazing a ceiling fan to help reduce the Description of sloped at 50 degrees. The air-conditioning load. North Example Building sunspace floor has a four-inch windows have an overhang with thick slab-on-grade with quarry a projection factor of 0.30. East A 1,504 square foot passive tile set in a mortar bed. The and west windows are small and solar, single-family home with sunspace is separated from the have no effective overhang an 8.3 ft. average ceiling height conditioned portion of the house because of the gable roof. South is used to illustrate how to fill in by sliding glass doors and a windows, including the the worksheets. See sketches' masonry fireplace wall. sunspace windows, have an for the building layout. A Sunspace ventilation is provided overhang with a proj ection variety of design features have to the outside by awning factor of 0.20. been incorporated into the windows located at the top and Titke-offs from the house are house to help illustrate how to bottom of the south wall. given in the worksheets. Refer handle different situations in South facing windows to the Circled values in the the worksheets. provide direct gain solar heating worksheet tables to locate where The building selected has to the dining area, kitchen and the various values which show good insulation as described on master bedroom. The south up in the worksheets come from. Worksheet I. glazing in the kitchen and Performance is found to be The east portion of the dining area provides heat to an satisfactory on all four house is slab on grade. The exposed slab-on-grade finished worksheets. great room and master bedroom with ceramic tile to provide are constructed over a direct gain heat storage. basement. The house faces 10 degrees to the east of true south.

js:I;r--~2~O~'--~T~-_----,22==--' ------:)i)li(:(; ...... J~~: ...... ~

Garage

.~

4040 Bedroom

Great Room

soss ' ~ 24' ~ ~ ...., ...... ,.. ,...... , ..... ;*...... , ...... ,········!':·~·····························x············ ...... l!

Green Bay. Wisconsin PASSIVE SOLAR DESIGN STRATEGIES

SOUTH ElEVATION

o 2 4 8 12 NORTH ELEVATION ......

·············································1

c::==::n2 '\ ABOVE GRADE SECTION o...... 2 4 8 12

Green Bay. Wisconsin 50 WORKED EXAMPLE

11iH"~-lnsulation

Insulation --l."''''''''''AOl Insulation.------4~~<91

. .~ .,.. -. ";" " ...... ,) ~ ::~r. .~_~ .' __ I . . ..•. : 1111 § 1111 §1II1§ 1111 ~11II§11I1§1II1 ' ,", "'1 §IIII § 1111 ';/ '., '. ...' 4, II" '''~IIII~' . • 4 ...• 4, • ~~(Xn~:7i' -1111 ;§ 1111 § 1111 § 1111 § I

," .. ~ '),'. ~: -~ ')'. ~ ," "~IIII§IIII§11II "', ..'." "'I§IIII§II .' .' .... ·"'§IIIIt..,~""",~:::",,:;~...c:...:J SLAB-ON-GRADE CRAWLSPACE FULL BASEMENT

TYPES OF FOUNDATIONS

Green Bay. Wisconsin PASSIVE SOLAR DESIGN STRATEGIES ~I

NOTE: These worksheets are completed for the example house described on the previous pages. Also the reference tables are marked up showing how the numbers are selected.

Green Bay, Worked Exam.ple Wisconsin

Green Bay. Wisconsin 52 WORKED EXAMPLE WORKSHEETS

General Project Information

Worksheet I: Conservation Performance Level

A. Envelope Heat Loss

Construction R-value Heat Description Area [Table A] Loss Qiilioga£[QQta 1Z-~D 'M A"n'~c:..- la"''''' + ~:::z.q 19 1Z:- ~6 ~. c...£iu..n:. 4~ + ~L~ 13 "R..¥\ ~ j:'" 'R.-lA> S'w~,.'" ""'1- + 1.'].1 = l' 1l-\C\ ~ ~~, law + ,...... ' = I loaulamd EIQQ[a + = + = ~Qo-aQIaJ: !:alaz:iog ~u.-.. f'c.- ~1W£AM. 1S~ S'Z.. + I." = 2..:1 - 'IJ." A'" ~f'1 &.AI-&. ".~ + = .I2!2w. lMefA,", \>WI £e4""" U1.f..' '"WJ + ~~ = 1 + = HD Btu/oF-h Total

B. Foundation Perimeter Heat Loss Heat Loss Factor Heat Description Perimeter [Table B] Loss Slaba-Qo-!:a[w;li U,..-"\ a 2.. X #.~ ~ l::IiiMig f3aailDiom ~.u 11'2.. X "!~ = '-'S !.!ob61fK.1 f3aailIlmJm X = ~i[ilDiti[ loauliMig Q[awla12ilQi!a X :::tLl. Btu/oF-h Total

C. Infiltration Heat Loss \1..... 63 X eJ,SQ X .018 = \ 'L.. Btu/oF-h Building Air Changes Volume per Hour

D. Total Heat Loss per Square Foot 24 X lA, + '5~ = 't.1l. Btu/DD-sf Total Heat Loss Floor Area (A+B+C)

E. Conservation Performance Level

Lt.1"1. X ~1't3 X 6.41~ :3'51~ Btu/yr-sf Total Heat Heating Degree Heating Degree Loss per Days [Table C] Day Multiplier Square Foot [Table C]

F. Comparison Conservation Performance (From Previous Calculation or from Table 0) 52.""\"30 Btu/yr-sf Com are Line E to Line F

Green Bay. Wisconsin PASSIVE SOLAR DESIGN STRATEGIES ::»~ Worksheet II: Auxili Heat Performance Level

A. Projected Area of Passive Solar Glazing

Solar System Rough Frame Net Area Adjustment Projected Reference Code Area Factor Factor [rable E] Area b<::=C-'Z- 88 X 0.80 X O.~6 ,~ 5S:D' Y18 X 0.80 X Q.-,s = ''25 X 0.80 X = X 0.80 X = X 0.80 X = X 0.80 X = X 0.80 X = 2.1' \9~ sf Total Area Total Projected Area

)~"'" + IS04- = Q!r!. Total Floor Total Projected Projected Area Area per Area Square Foot

B. Load Collector Ratio

24 X 2..~' + l4\"+ = 3J Total Total Heat Loss Projected [Worksheet I] Area

C. Solar Savings Fraction

System Solar Savings Solar System Projected Fraction Reference Code Area [rable F] ~t:..L ~q X O·Z.D r:t.fD ~.{""']) ( lIS X D.US = 3,·25 X = X = X X = X =

-r lq4 = 1!J.1.~ "'oDSTotal Total Solar Projected Savings Area Fraction

D. Auxiliary Heat Performance Level

[1 - D.7:l X ~'3 Z.9US Btu/yr-sf Solar Conservation Savings Performance Fraction Level [Worksheet I, Step E]

E. Comparative Auxiliary Heat Performance (From Previous Calculation or from Table G) ~~" Btu/yr-sf Com are Line D to Line E Green Bay, Wisconsin 54 WORKED EXAMPLE WORKSHEETS Worksheet III: Thermal Mass Comfort

A. Heat Capacity of Sheetrock and Interior Furnishings

Unit Total Heat Heat Floor Area Capacity Capacity Booms with Direct Gajn La''''' X 4.7 = 2 ..1(,1 Spaces Connected to Direct Gajn SPaces ______g~ X 4.5 = ~z..11 {/-t$1- Btu/OF Total

B. Heat Capacity of Mass Surfaces Enclosing Direct Gain Spaces

Unit Heat Mass Description Capacity Total Heat (include thickness) Area [Table H] Capacity TrombeWalls X 8.8

~Wrwruls ______X 10.4 Exposed Slab in Syn ______'03 X 13.4 = '3i41 ExPosed Slab Not in Syn I'll X 1.8 = ~] X = X = X = "2.1 Btu/oF Total

C. Heat Capacity of Mass Surfaces Enclosing Spaces Connected to Direct Gain Spaces

Unit Heat Mass Description Capacity Total Heat (include thickness) Area [Table H] Capacity TrombeWalls X 3.8 WWBrwruls ______~------X 4.2 4'" ,\\ X ~:l LUi X = X LtU Btu/OF Total

D. Total Heat Capacity g~o Btu/oF (A+B+C)

E. Total Heat Capacity per Square Foot a"'GD + lS:o~ ~, Btu/OF-sf Total Heat Conditioned Capacity Floor Area

F. Clear Winter Day Temperature Swing

Total Comfort Projected Area Factor [Worksheet,g II] [Table I] Di[!~!

QiiliDg~QQtli l!j X I.DO X O.~'J X 2.1.3 = '2.H'-' IJ X ,.ao X ~!"" X 2.-'1.'3 = "J X X X = ~ lL X nfa c:'I.]D X u.s = ViJ X nfa X = QQQm J X nfa 6.~ X "·s = II "9- kBtu/yr Total B. Non-solar Glazing Rough Frame Net Area Shade Factor Heat Gain Description Area Factor [fable M] Factor [fable L] Load t),':\ , ~QctI:l~liillili LtO X 0.80 X X 1~.6 = ~io X 0.80 X X I'; , !;iillit ~Iiillili 6 X 0.80 X D.eD X l!l·'Z- = X 0.80 X X = Wilit~liillili , X 0.80 X ~." X "'1.1 = "S X 0.80 X X = Slsl!ligbtli X 0.80 X X X 0.80 X X = :u.q kBtu/yr Total C. Solar Glazing

Solar System Rough Frame Net Area Shade Factor Heat Gain Description Area Factor [fable M] Factor [fable L] Load

l:li[i:Qt !3ii1iD 68. X 0.80 X tJ.Izi X 31.~ \52..1 X 0.80 X X = StQ[iiI!;Ii Wiilllli X 0.80 X X = X 0.80 X X = SUDliAiilQi '2.t:IS X 0.80 X \.00 X 12.S = 2.'~C X 0.80 X X = ~J kBtu/yr Total D. Internal Gain IDtJO +( Ltz.o X :l ) = ZZI!O kBtu/yr Constant Variable Number of Component Component Bedrooms [fable N] [fable N] E. CooUng Load per Square Foot 1,000 X .,~ + \~o,+ Lt~'U+ Btu/yr-sf (A+B+C+D) Floor Area F. Adjustment for Thermal Mass and Ventilation Btu/yr-sf Me) ... LC::act vc,...n'• '-Ji4.L''-'N4: -:SllLt r.A" [fable 0] G. CoollDg- Performance Level \~O Btu/yr-sf (E -F) H. Comparison CooUng Performance (From Previous Calculation or from Table P) Slole Btu/yr-sf Com are Line G to Line H

Green Bay, Wisconsin 56 WORKED EXAMPLE TABLES

Table A-continued .. Table A-Equivalent Thermal Table D-Base Case Conservation Performance of Assemblies A5-Doors Performance (Btu/~ R-values (hr-F-sf/Btu) Solid wood with 2.2 Base Case ~ Weatherstripping A1-Ceillngs/Roofs Metal with rigid @ foam core Attic Insulation R-value Table E-Projected Area Adjustment Construction R-30 R-38 R-49 R-SO Factors 27.9 35.9 4S.9 ~ Table B-Perimeter Heat Loss Degrees off ~ Solar System Type Factors for Slabs-on-Grade and True G" ~ SSB, Framed Insulation R-value Unheated Basements (Btu/h-F-ft) South , SSC SSE Construction R-19 R-22 R-30 R-38 o 1.00 . 0.75 Heated Unheated Insulated 2xS at IS'oc 14.7 15.8 IS.3 Perimeter Siabs-on- Base- Base- Crawl- 105 4W0.9 I'.75 0.750.74 2xS at 24'oc 15.3 IS.5 17.1 Insulation Grade ments ments spaces 15 .7 0.4 0.73 2xB at IS'oc 17.0 18.9 20.S 21.1 20 0.94 0.72 0.70 2XB at 24'oc 17.S 19.5 21.S 22.2 None O.B 1.3 1.1 1.1 R-5 0.8 0.7 O.S 25 0.91 0.69 0.68 2xl0 at IS'oc 18.1 20.1 24.5 25.7 30 0.87 0.66 0.65 2xl0 at 24'oc 18.4 20.7 25.5 2S.8 R-7 ~ O.S 0.5 2x12 at IS'oc 18.8 21.0 25.5 R-ll 0.3 0.5 0.4 2x12 at 24 'oc 19.0 21.4 27.3 R-19 0.2 ~ 0.5 0.3 R-30 0.1 0.3 0.4 0.2 ~ Table F-8olar System Saving Fractions A2-FramedWalls Single Table C-HeatiDg Degree Days Wall Insulation R-value (F-day) F1-Direct Gain R-19 R-25 Framing R-ll R-13 Load DGC1 DGC2 DGC3 2X4 at IS'oc 12.0 13.S Collector Double Low-e R-9 Night Ratio Glazing Glazing Insulation 2x4 at 24'oc 12.7 13.9 C1-Heating Degree Days (Base 65~ 2XS at 16'oc 14.1 15.4 19.2 400 0.02 0.03 0.04 2xS at 24'oc 14.3 15.S 4W 19.8 Green Bay 8,143 300 0.03 0.04 0.05 Antigo , 4 200 0.04 0.05 0.07 Double Appleton 7,728 150 0.05 0.07 0.09 Wall Total Thickness (inches) 0.13 Menominee 7,913 100 0.06 0.10 Framing B 10 12 14 80 0.07 0.11 0.16 25.0 31.3 37.5 43.8 New London 7,77B 60 0.09 0.14 0.20 Octonto .8,024 50 0.10 0.16 0.23 0.11 0.18 0.25 The R-value of insulating sheathing should be added to Oshkosh 7,S92 Rosholt 8,328 0.11 0.27 the values in this table. 0.12 iro.• ~ 0.30 Shawano 7,953 4P 0.13 . 3 0.34 Stevens Point 8,107 25 0.14 0.26 0.38 A3-Insulated Floors Sturgeon Bay 7,89B 20 0.14 0.30 0.44 15 0.15 0.35 0.52 Insulation R-value Two Rivers 7,802 Framing R-l1 R-19 R-30 R-38 Waupaca 7,724 2xss at IS'oc 18.2 23.8 29.9 Wasau AP 8,5S5 F2-Trombe Walls 2XSs at 24'oc lB.4 24.5 31.5 TWF3 TWA3 TWJ2 TWI4 2x8s at IS'oc 18.B 24.9 31.7 3S.0 Load Unvented Vented Unvented Unvented 2xBs at 24'oc 18.9 25.4 33.1 37.9 C2-Heatlng Degree Day Multiplier Collector Non- Non- Selec- Night 2xl0 at IS'oc 19.3 25.B 33.4 3B.l Passive Solar Ratio selective selective live Insulation 34.4 39.B 2Xl0 at 24'oc 19.3 2S.1 Heat Loss Glazing Area per 400 0.01 0.03 0.00 0.00 19.7 2S.5 34.7 39.B 2x12 at IS'oc per Square per Square Foot 300 0.01 0.04 0.01 0.00 19.5 2S.7 35.5 41.2 2x12 at 24'oc Foot .00 .05 .10 .15 .20 200 0.03 0.05 0.04 0.01 These R-values include the buffering effect of a 12.00 1.07 1.08 1.08 1.08 1.09 150 0.04 0.06 0.07 0.04 ventilated crawlspace or uncondHioned basement. 11.50 1.07 1.07 1.0B 1.0B 1.08 100 0.06 0.09 0.12 O.OB 11.00 1.0S 1.07 1.07 1.07 1.08 80 0.07 0.10 0.15 0.11 10.50 1. OS 1.0S 1.07 1.07 1.07 60 0.09 0.12 0.20 0.15 10.00 1.05 1.06 1.06 1.06 1.07 50 0.11 0.14 0.24 0.19 A4-Windows 9.50 1.04 1.05 1.05 1.06 1.06 45 0.12 0.15 0.26 0.21 Air Gap 9.00 1.04 1.04 1.05 1.05 1.06 40 0.13 0.16 0.29 0.23 8.50 1.03 1.03 1.04 1.04 1.05 35 0.14 0.17 0.32 0.26 1/4 in. 1/2 in. 1/2 in. argon 8.00 1.02 1.03 1.03 1.04 1.04 30 0.16 0.19 0.35 0.29 7.50 1.01 . 1.02 1.02 1.03 1.04 25 0.18 0.21 0.40 0.34 Standard Metal Frame 7.00 0.99 1.00 1.01 1.02 1.03 20 0.20 0.23 0.46 0.39 Single .9 6.50 0.98 0.99 1.00 1.01 1.02 15 0.23 0.26 0.54 0.47 Double 1.1 1.2 1.2 6.00 0.96 0.98 0.99 1.00 1.01 Low-e (e<=0.40) 1.2 1.3 1.3 5.50 0.94 0.96 0.99 Metal frame with thermal break 0.92 0.93 .9 7 0.98 Double 1.5 I.S 1.7 (:f) 0.89 0.91 o. 0.9 0.96 Low-e (e<:O.40) I.S I.B 4.00 0.86 0.88 0.90 . 0.94 Low-e (e<=0.20) 1.7 @ 2.0 H0.89 0.91 3.50 0.81 0.85 0.87 Wood frame with vinyl cladding 3.00 0.76 0.80 0.B3 0.86 0.88 Double 2.0 2.1 2.2 2.50 0.69 0.74 0.78 0.82 0.85 Low-e (e<:O.40) 2.1 2.4 2.5 2.00 0.58 0.66 0.72 0.77 0.81 Low-e (e<=0.20) 2.2 2.S 2.7 Low-e (e<=O.1 0) 2.3 2.S 2.9 These R-values are based on a 3 mph wind speed and are typical for the entire rough framed opening. Manufacture's data, based on National Fenestration Rating Council procedures, should be used when available. One half the R-value of movable insulation should be added, when appropriate.

Green Bay, Wisconsin PASSIVE SOLAR DESIGN STRATEGIES '-JI

F3-Water Walls Table H-Umt Heat Capacities (Btu/F-st) Load WWA3 WWB4 WWC2 Ceiling/roofs Collector No Night Night Selective Walls and Doors Ratio Insulation Insulation Surface North Glass 400 0.02 0.00 0.00 H1-Mass Surfaces Enclosing Direct Gain East Glass 300 Q.02 0.00 0.00 Spaces West Glass 200 0.04 0.02 0.03 Skylights 150 0.06 0.05 0.05 Thickness (inches) Material 2 3 4 6 8 12 Direct Gain Glazing 100 0.08 0.10 0.10 Trombe Walls and 80 0.10 0.14 0.14 Poured Conc. 1.8 4.3 6.7 8.8 11.3 11.5 10.3 Water Walls 60 0.12 0.19 0.19 Conc. Masonry 1.8 4.2 6.5 8.4 10.2 10.0 9.0 Sunspaces 50 0.14 0.23 0.22 Face Brick 2.0 4.7 7.1 9.0 10.4 9.9 9.0 SSAl 12.8 45 0.15 0.26 0.25 Flag stone 2.1 4.8 7.1 8.5 8.6 8.0 7.6 SSBI 12.8 40 0.16 0.28 0.27 Builder Brick 1.5 3.7 5.4 6.5 6.6 6.0 5.8 SSCl 35 0.18 0.32 0.30 Adobe 1.3 3.2 4.8 5.5 5.4 4.9 4.8 SSDl 30 0.19 0.36 0.34 Hardwood 0.4 1.4 1.8 1.7 1.5 1.5 1.5 SSEI 25 0.21 0.41 0.38 Water 5.2 10.4 15.6 20.8 31.2 41.6 62.4 ~ 20 0.24 0.47 0.44 . 15 0.27 0.55 0.52 H2-Rooms with no Direct Solar Gain Table M-Sbading Factors F4-Sunspaces Thickness (inches) Projection Material 2 3 4 6 8 12 Load Factor ~ East North West Collector Sunspace Type Poured Conc. 1.7 3.0 3.6 3.8 3.7 3.6 3.4 0.00 1.00 ~. 1.00 1.00) Ratio SSAl SSBl SSCl SSDl SSE 1 Conc. Masonry 1.6 2.9 3.5 4.¥ 3.6 3.4 3.2 0.20 0.97 0.94 0.97 400 0.08 0.06 0.02 0.06 0.04 Face Brick 1.8 3.1 3.6 3. 3.5 3.4 3.2 0.40 .68. 1»0 300 0.08 0.07 0.02 0.07 0.05 Flag stone 1.9 3.1 3.4 .4 3.2 3.1 3.0 0.60 0.28 .~ ~~"11 ~.go 200 0.10 0.08 0.04 0.09 0.07 Builder Brick 1.4 2.6 3.0 3.1 2.9 2.7 2.7 0.80 0.19 0.45 &rs. 0.46 150 0.12 0.09 0.05 0.11 0.08 Adobe 1.2 2.4 2.8 2.8 2.6 2.4 2.4 1.00 0.10 0.36 0.36 0.36 100 0.14 0.11 0.07 0.14 0.11 Hardwood 0.5 1.1 1.3 1.2 1.1 1.0 1.1 1.20 0.04 0.26 0.27 0.27 80 0.16 0.13 0.08 0.16 0.12 60 0.18 0.15 0.10 0.19 0.15 ~MuHiply by 0.8 for low-e glass, 0.7 for tinted glass and 50 0.20 0.16 0.12 0.21 0.16 0.6 for low-e tinted glass. 45 0.21 0.17 0.12 0.22 0.17 A 0.22 0.18 0.13 ~ 0.18 Table I-Comfort Factors (Btu/st) Oi' 0.23 0.19 0.14 0.25 0.19 Direct Gain 30 0.25 0.21 0.16 . 0.20 dJf)) 25 0.26 0.22 0.17 0.29 0.22 Suns paces and @) Table N-Intemal Gain Factors 20 0.29 0.24 0.19 0.32 0.23 Vented Trombe Walls Constant Component ~ kBtulyr 15 0.32 0.27 0.21 0.35 0.25 Variable Component (!!§) kBtulyr-BR

Table J-Radiant Barrier Factors Radiant Barrier 0.75 Table O-Thermal Mass and No Radiant Barrier ~ Ventilation Adjustment (Btu/yr-st) Total Heat Night Night No Night No Night Capacity Vent w/ Vent w/ No Vent w/ Vent w/ No per SF Ceil. Fan Ceil. Fan Ceil. Fan Ceil. Fan 0.0 2,330 510 1,520 -420 Table K-Solar Absorptances 1.0 3,110 1,430 2,310 500 Color Absorptance 2.0 3,570 1,960 2,770 1,030 3.0 3,840 2,280 3,040 1,340 Gloss WhHe 4,000 2,460 &!'0 1,530 Semi-gloss WhHe . 4,100 2,560 , 1,630 Light Green 6.0 4,150 2,630 1,700 Kelly Green .0 4,190 2,660 3,380 1,730 Medium Blue ~0.51 dP 8.0 4,210 2,680 3,400 1,750 Medium Yellow 0.57 9.0 4,220 2,690 3,410 1,760 Medium Orange 0.58 10.0 4,220 2,700 3,420 1,770 Medium Green 0.59 Light Buff Brick 0.60 Total heat capacity per square foot is calculated on Bare Conc'rete Worksheet III, Step E. Red Brick ~ Medium Red 'ira Medium Brown 0.84 Dark Blue-Grey 0.88 Dark Brown 0.88 Table P-Base Case Cooling Table G-Base Case AuDliary Heat Performance (Btu/s~ Perfonnance (Btu/~ Base Case ~ Base Case ~

Green Bay. Wisconsin 58 WORKED EXAMPLE TABLES

Green Bay. Wisconsin PASSIVE SOLAR DESIGN STRATEGIES 59

Note: This is a generic example to explain how to fill out the worksheets. For an example specific to this book, refer to the worked example on the prior pages. The actual house design used for both examples is the same, but specific numerical values will be different.

Anytown , USA

Anytown, USA 60 INTRODUCTION Introduction A separate worksheet is The estimates from provided for each of four Worksheets I and II are based on Purpose separate performance levels a heating thermostat setting of perfo~ance level and 70°F. The .estimates from The purpose of the Any Town, associated target. These are Worksheet IV are based on a USA section is to explain how to deSCribed below: cooling thermostat setting of use the passive solar Worksheet I: Conservation 78°F with no ceiling fans and worksheets in the Passive Solar Performance Level: the 82°F with ceiling fans. Design Strategies: Guidelines for estimated heat energy needed by The worksheets are Home BUilding. Separate the building each year from both supported by a number of data Worksheets booklets are the solar and auxiliary heating tables. The data tables are given available for specific locations systems. The units are a letter deSignation and are throughout the continental Btu/yr-sf. referenced when applicable next USA. Each booklet contains Worksheet II: Auxiliary Heat to each worksheet entry. detailed technical data for a Performance Level: the A description and drawings specific location. Although the estimated heat that must be of the example building are example presented in this provided each year by the provided below, followed by booklet is for a moderate mid­ auxiliary heating system. This completed worksheets. Data Atlantic climate, the procedure worksheet accounts for the solar tables have also been included is presented in a general savings. The units are when appropriate. manner and is intended to be . Btu/yr-sf. Each step of the worksheets used for all locations. Worksheet III: Thermal is then explained in detail. Mass / Comfort: the temperature General Description swing expected on aclear winter day with the auxiliary heating of Worksheets system not operating. The units \ are OF. The Worksheets booklet for each location provides an easy-to-use Worksheet N: Summer Cooling calculation procedure, allowing Performance Level: the the designer to estimate the estimated annual cooling load of performance level of a particular the building. The units are building design and compare it Btu/yr-sf. against a base-case performance level or against the performance of the builder's more conventional house.

Anytown, USA PASSIVE SOLAR DESIGN STRATEGIES 61

Description of The building has an South facing windows attached sunspace. The provide direct gain solar heating Example Building ( sunspace floor has a four-inch to the dining area. kitchen and ) thick slab-on-grade with quarry master bedroom. The south A 1.504 square foot passive tile set in a mortar bed. The glazing in the kitchen and solar. single-family home with sunspace is separated from the dining area provides heat to an an 8.3 ft. average ceiling height conditioned portion of the house exposed slab-on-grade. is used to illustrate how to use by sliding glass doors and a The east portion of the the worksheets. A floor plan. masonry fireplace wall. Awning house is slab-on-grade building elevations. building windows located at the top and construction. The great room sections and details are shown bottom of the south wall provide and master bedroom suite are below. outside ventilation for the raised floor construction. The sunspace. slab-on-grade floor in the kitchen and dining area is finished with ceramic tile so that the floor may function as thermal mass. The exterior doors are metal with a foam core center.

~r--~2~O~' --.....;*~i~ __ ..!:2=2-'--~r· ...... ·.... ·...... g4.'...... :...... \

Garage

4040

Bedroom

Great Room

Master Bedroom ;...,... Suns pace

8088 8088 14' o 2 4 8 12 FLOOR PLAN ----

AnytOWD, USA 62 INTRODUCTION

SOUTH ELEVATION

024 B 12 NORTH ELEVATION

'...... ---- ...... ::::::::::::::J

"r ABOVE GRADE SECTION ) 02...... 4 B 12

Insulation,.---i''ti"*t:=;::::::l I . ., ...... ' : .r'''<:'.:l.-m~'-'-:! """"!1rf"'_'11IT'nl-.LA .' .' • § 1111 § III I;, : .....: . ini~),i~, §1I11 § 1111 ., ..•• ". 1I11§1Il1t=' •.• ' :." .•• 1I11§1II" .• : .' ~'. 1111" ", ....• "II .~. ", . ....111' . .'" .•.... . " . ",'.' . . . -... '. -. .' ... ", .. ' ... " . ,' . • ' II' .' II'

SLAB-ON-GRADE CRAWLSPACE FULL BASEMENT

\ TYPES OF FOUNDATIONS /

Anytown, USA PASSIVE SOLAR DESIGN STRATEGIES 63

General pro~ect Information

~:Area 1504 sf

Worksheet I: Conservation Performance Level

A. Envelope Heat Loss Construction R-value Heat Description Area [Table A] Loss

Q!!iliog~L[QQt~ B-;36 io 8!liQ ]Q64 + ;3f2!:! = ;3Q B-;3Q io Qrull!!Qml Q!!iliog 42Q + 24f2 = ]I ..,... WiillI~ B-l!:!± B-Z SIl!!iillIliog io BigiQ IO~!JliiI!iQO !:!!:!2 24Z = 4Q B-1!:! io ~iilmg!! 14Q + lZZ 6 IO~!JliiI!!!Q EIQQ[~ B-1!:! io EIQQ[ Qll!![ ~!!ois!Q Q[5nIl1~I2ii1Q!! Z64 + 2f26 = ;3Q + = ~Qo-~QliiI[ ~Iiili:iog OQ!Jbl!! !:aliilZ!!Q WQQQ E[iillD!! liZ' iili[ giill2 f22 + 16 2!:! - L.QY:l-i; (!!:;;- 4Q) + OQQ[~ M!!!iilllI:li!1l EQiillD QQ[!! 4Q + f2!:! = Z + = 1121 Btu/OF-h Total B. Foundation Perimeter Heat.Loss Heat Loss Factor Heat Description Perimeter [Table B] Loss

Sliilb~-QO-!:a[iilQ!! B-Z 62 X Q;3Q 2f2 ~ H!!iilis!Q BiilS!!ID!!O!S X = I Uoll!!ru!!Q Eliil~!!ID!!O!~ X = E!![iID!!t!![ IO~!Jliilt!!Q Qmll:ll~I2ii1Q!!~ X = 2f2 Btu/oF-h Total

C. Infiltration Heat Loss 1246;3 X Qf2Q X .018 112 Btu/OF-h Building Air Changes Volume per Hour

D. Total Heat Loss per Square Foot

24 X 2~6 + lf2Q4 = 4Z!2 Btu/DD-sf Total Heat Loss Floor Area (A+B+C)

E. Conservation Performance Level

H!2 X nQ;3 X Qn = lZQn Btu/yr-sf Total Heat Heating Degree Heating Degree Loss per Days [Table C] Day Multiplier Square Foot [Table C]

F. Comparison Conservation Performance (From Previous Calculation or from Table O) 2f2 ;3!2Q Btu/yr-sf Com are Line E to Line F

Anytown, USA 64 CONSERVATION PERFORMANCE LEVEL

Worksheet I: Step A. Envelope Heat Loss Ceilings/Roofs Conservation The first step is to calculate the There are two types of Performance Level heat loss through the building ceiling/roof construction in the) Worksheet I is essentially a heat envelope. The building envelope example building. R-38 mineral \ loss calculation, similar to the consists of all walls, roofs, insulation is located in an attic type of calculation made to size floors, non-solar windows and space, and R-30 insulation is heating and cooling equipment. doors that enclose the located in the framed cathedral The major difference is that the conditioned space of the house. ceiling. The total R-value is calculation does not consider Heat loss for each envelope selected from Table Al for each heat loss through any of the component is calculated by ceiling/ roof component. The passive solar systems. The dividing the surface area of the values in Table Al account for following building corriponents component by the total R-value. the buffering effect of the attic in the example building are not The total envelope heat loss is (when applicable), the ceiling considered in the calculation: the sum of the heat loss for all material (sheetrock) and the • Heat loss through direct gain of the envelope components. effect of framing. solar glazing. Table A in the Worksheets • Heat loss through walls and booklet contains R-values that A 1-Ceilings/Roofs Attic Insulation R-value windows that separate the may be used in the calculation. Construction R-30 I!1J R-49 R-60 house from the sunspace. There are actually five separate 27.9 35 46.9 57.9 Framed Insulation R-value If the example building had tables labeled AI, A2, A3, A4 Construction R-19 R-22 R-30 R-38 2x6 at 16"oc 14.7 15.8 16.3 - Trombe walls or water walls, and A5. A separate table is 2x6 at 24'oc 15.3 16.5 17.1 - heat loss through these passive provided fQr ceilings/roofs, 2x8 at 16"oc 17.0 18.9 20.6 21.1 2x8 at 24"oc 17.6 19.6~ 22.2 solar systems would also be walls, floors, windows and 2x10 at 16"oc 18.1 20.1 24. 25.7 2x10 at 24"oc 18.4 20.7 . 26.8 excluded from the calculation. doors. The R-values' in these 2x12 at 16"oc 18.8 21.0 25.5 30.1 Heat loss from the passive tables include the thermal 2x12 at 24 'oc 19.0 21.4 27.3 31.4 solar energy systems is excluded resistance of both the insulation The area and R-value of the ) since the solar savings fractions and other materials that two different types of in Worksheet II take these losses typically make up the construction are entered on two into account. construction assembly such as lines of the table under exterior sheathing and "ceilings/roofs" and the heat sheetrock. They also account loss is calculated by dividing the for framing members that surface area by the total . penetrate the insulation and R-value. Note that the ceiling reduce the effectiveness. over the sunspace is not included in this calculation.

Anytown, USA PASSIVE SOLAR DESIGN STRATEGIES 65

Walls The R-value of each wall The total R-value is selected There are two types of wall type is detennined from Table from Table A3, which considers '\ construction in the example A2 in the Worksheets booklet. the buffering effect of the ) building. The typical exterior The R-value of both wall types is crawlspace as well as framing wall is of 2x6 wood frame 17.7 from the table, but since and the floor materials. The construction with R-19 mineral the first wall type has R-7 area and R-value is entered on insulation in the cavity. An insulating sheathing, this is one line of the table and the insulating sheathing with an R- added to the value from the heat loss is calculated by . 7 rating is attached to the table so that 24.7 is used in the dividing the area by the R-value. exterior surface of the framing. calculations. These R-values The wall is finished with 1/2 along with the associated areas A3-lnsulated Floors Insulation R·value inch sheetrock on the inside are entered on two lines of the Framing R-11 R-19 R-30 R-38 2x6s at 16"oc 18.2 23.8 29.9 and a brick veneer on the table and the heat loss is 2x6s at 24"oc 18.4 24.5 31.5 outside. calculated by dividing each 2x8s at 16"oc 18.8 24.9 31.7 36.0 2x8s at 24"oc 18.9 33.1 37.9 The second type of wall surface area by the 2x10 at 16"oc 19.3 4W25.8 33.4 38.1 2x10 at 24"oc 19.3 .1 34.4 39.8 construction separates the corresponding R-value. 2x12 at 16"oc 19.7 26.5 34.7 39.8 house from the garage. This 2x12 at 24"oc 19.6 26.7 35.5 41.2 These R·values include the buffering effect of a wall is also of 2x6 wood frame A2-Framed Walls ventilated crawlspace or unconditioned basement. Single Wall Insulation R·value construction With R-19 in the Framing R-11 R-13 R-19 R-25 Had there been different cavity, but it does not have the 2x4 at 16"oc 12.0 13.6 insulation conditions for the 2x4 at 24"oc 12.7 13.9 ~ - insulating sheathing or the 2x6 at 16"oc 14.1 15.4 17. 19.2 raised floor, an additional line of 2x6 at 24"oc 14.3 15.6 . 19.8 brick veneer. Note that the Double the table would be completed for Wall Total Thickness (inches) walls that separate the house Framing 8 10 12 14 each condition. from the sunspace are not 25.0 31.3 37.5 43.8 If the example building had included...... The R·value of insulating. sheathing should be insulated floors over a garage or \ added to the values in this table. / It is necessary to measure unheated basement, these the surface area of each type of components would also be wall construction. The surface Floors included in this step. area may be determined by Only the raised floor is As an alternative to multiplying the length of wall by considered in this step of the insulating between the floor the average height and heat loss calculation; heat loss joists, the perimeter walls of the subtracting the area of doors from the slab-on-grade floor is crawlspace could have b~en and windows. conSidered in Step B. There is insulated and floor insulation one type of raised floor eliminated. When this construction in the example technique is used, the perimeter building. R-19 mineral heat loss method in Step B insulation is placed between should be used. Step A only 2xlO floor joists at 16 inches on includes floors when insulation center; the crawlspace beneath is placed in the floor assembly. is ventilated.

Anytown, USA 66 CONSERVATION PERFORMANCE LEVEL

Non-solar Glazing Windows in the example These values are entered in Next, heat loss from the non­ building are all double-pane the table and the heat loss is solar glazing is calculated. Note wood windows with a 1/2 inch calculated by dividing the door that the passive solar direct gain air space between the panes. areas by the R-value. If the glazing is not included. Also the The R-value for this window example building had more than windows that separate the type is 2.1, selected from Table one door type (different house from the sunspace are A4. R-values), then additional lines not included. The non-solar window area of the table would be completed. The rough frame opening of is taken from the building plans. each window is generally used These values are entered in the Total for the window area. This is table and the heat loss is The heat loss of all components because the R-values presented calculated by dividing the of the building envelope is in Table A4 and most heat loss window area by the window summed at the bottom of the data presented by window R-value. If the example building table and this completes Step A manufacturers is for the rough had more than one window type of the worksheet. frame opening. Using the rough (different R-values), then frame opening also makes it additional lines of the table easier to estimate window areas would be completed. since windows are usually specified on the plans in terms Doors of the rough frame dimensions. The doors are the last component of the envelope to A4-Windows Air Gap consider. The example building 1/4 in. 1/2 in. 1/2 in. argon has two exterior doors: the main Slandar'd Metal Frame Single .9 entrance and an additional door Double 1.1 1.2 1.2 Low-e (e<=0:40) 1.2 1.3 1.3 to the garage. These have a Metal frame with thermal break total surface area of 40 square Double 1.5 1.7 Low-e le<=0.40} 1.6 '. I.S feet and an R-value is selected Low-e e<=0.20} 1.7 2.0 Wood frame with vinyl cladding from Table A5. Note that the Double 2.0 2.1 2.2 Low-e (e<=0.40l 2.1 2.4 2.5 door that separates the garage Low-e le<=0.20 2.2 2.6 2.7 Low-e e<=0.10 2.3 2.6 2.9 from the exterior is not included since the garage is These R-values are based on a 3 mph wind speed and are typical for the entire rough framed opening. unconditioned. Manufacture's data, based on National Fenestration Rating Council procedures, should be used when available. One half the R-value of AS-Doors movable insulation should be added, when Solid wood with 2.2 appropriate. Weatherstripping Metal with rigid C1i) foam core

Anytown, USA PASSIVE SOLAR DESIGN STRATEGIES 67

Table B-Perimeter Heat Loss Factors Step B. Foundation for Slabs·on·Grade and Unheated The building volume is Perimeter Heat Loss . Basements (Btuth·F·ft) calculated by multiplying the Heated Unheated Insulated ) Foundation heat loss from Perimeter Siabs-on- Base· Base- Crawl· average ceiling height by the slabs-on-grade. basements and Insulation Grade ments ments spaces conditioned floor area. In this None 0.8 1.3 1.1 1.1 insulated crawispaces is R 5 ~ 0.8 0.7 0.6 example the average ceiling R:7 0.3 0.7 0.6 0.5 estimated by multiplying the R·11 . 0.6 0.5 0.4 height is 8.3 ft. The conditioned R-19 0.2· 0.4 0.5 0.3 length of perimeter times an R-30 0.1 0.3 0.4 0.2 floor area is 1,504 sf which does appropriate heat loss factor When a raised floor assembly is not include the garage or the taken from Table B. not insulated, for instance, over sunspace. The resulting The dining area, kitchen and crawlspaces insulated at the building volume is 12,483 cubic secondary bedrooms in the perimeter or basements, heat feet. example house have slab-on­ loss occurs primarily at the The units of infiltration heat grade construction. R-7 perimeter. loss are Btu;oF-h, the same as insulation is installed around The example house does not for the building envelope and the perimeter. have a basement or a heated the foundation perimeter. The heat loss factor for the crawlspace, but if it did, the Step D. Total Heat Loss per slab edge is 0.3, selected from foundation heat loss would be Square Foot Table B. The heat loss factor is calculated by multip1ying the The total building heat loss is multiplied by the perimeter to perimeter of these elements by a the sum of the heat loss for the calculate the heat loss. The heat loss factor selected from building envelope (Step A), the units of heat loss, using the Table B. foundation perimeter (Step B) perimeter method, are the same When houses have heated and infiltration (Step C). For as for the building envelope basements, heat loss from , residences this value will range calculated in the previous step. basement walls located above between 200 and 500. It Note that sunspace slab is not grade would be included in represents the Btu of heat loss included in this calculation. Step A. The slab edge perimeter from the building envelope over adjacent to the crawlspace and Step C. Infiltration Heat Loss the period of an hour when it is the sunspace is also excluded. The heat loss from infiltration or one OF colder outside than air leakage is estimated by inside. This total heat loss, of multiplying the building volume course, does not include heat times the air changes per hour loss from the solar systems, times a heat loss factor of 0.018. including direct gain glazing. The example building is The result of Step D, estimated to have an infiltration however, is the annual heat loss rate of 0.50 based on local per degree day per square foot. building experience. This value is calculated by mUltiplying the total heat loss by 24 hours/ day and dividing by the conditioned floor area.

Anytown, USA 68 CONSERVATION PERFORMANCE LEVEL

Step E. Conservation The heating degree days are Step F. Comparison Performance Level selected from Table C 1 and Conservation Performance Once the total heat loss per based on specific locations. The The conservation performance square foot is calculated, the heating degree day multiplier is level for the proposed design conservation perfonnance level selected from Table C2 and is may be compared to the base may be calculated by based on the total heat loss per case perfonnance level for the multiplying the total heat loss square foot (Step D) and the area, given in Table D. per square foot (Step D) by the passive solar glazing area per Table D-Base Case Conservation heating degree days times the square foot of floor area Performance (Btu/v. • heating degree day multiplier. (Worksheet II, Step A). Base Case 25,38 Alternatively, the C1-Heating Degree Days ~ 65°F) C2-Heating Degree Day Multiplier conservation perfonnance level Raleigh·Durham ~ Passive Solar Heat Loss Glazing Area per may be compared to other This value is from TMY weather tapes and per Square per Square Foot should be used for Worksheet Calculations. Foot .00 .05 .10 .15 .20 building designs considered by It will vary from long term averages. 8.00 1.03 1.05 1.07 1.09 1.11 7.50 1.01 1.04 1.06 1.07 1.10 the builder to be typical of the 7.00 0.99 1.02 1.04 1.06 1.08 6.50 0.97 1.00 1.02 1.04 1.06 area. In this case, the 6.00 0.94 0.97 1.00 1.03 1.05 worksheets would first be 0.90 0.94 0.98~. 1.03 .00 0.86 0.91 0.95 . 1.01 completed for the typical design ~5 Q~ Q~ Q~ Q9 Q~ ~. 0 0.77 0.83 0.88 . 2 0.96 and the results of these 3.50 0.72 0.78 0.83 0.88 0.93 calculations would be entered in The conservation Step F. perfonnance level for the If the conservation example building is compared to per.(onnance level of the the base case conservation proposed building (Step E) is perfonnance level in the next greater than the base case or ) step. typical-design conservation perfonnance level. the designer should conSider additional building insulation or reduced non-solar glass area.

Anytown; USA PASSIVE SOLAR DESIGN STRATEGIES 69

Worksheet II: Auxili Heat Performance Level / A. Projected Area of Passive Solar Glazing I. ) Solar System Rough Frame Net Area Adjustment Projected Reference Code Area Factor Factor [Table E] Area

Q~QI ee X 0.80 X ~e fl~ SSQI 2Qe X 0.80 X ~e jfl~ X 0.80 X X 0.80 X = X 0.80 X = X 0.80 X = X 0.80 X = 2~fl 2~2 sf Total Area Total Projected Area

2~2 -;- jf!Q4 = jf! Total Floor Total Projected Projected Area Area per Area Square Foot

B. Load Collector Ratio

24 X 2~a + 2~2 = ~Q e~ Total Total Heat Loss Projected [Worksheet I] Area

C. Solar Savings Fraction ) System / Solar Savings Solar System Projected Fraction Reference Code Area [Table F]

Q~Qj fl~ X 44 ~Q ~fl SSQl jfl~ X 4f! = Z~~f! X = X = X = X = X =

jQ~ Zj + 2~2 Q4f! Total Total Solar Projected Savings Area Fraction D. Auxiliary Heat Performance Level

[1 - Q4f! jx 1ZQ~Z = ~Q4~ Btu/yr-sf Solar Conservation Savings Performance Fraction Level [Worksheet I, Step E]

E. Comparative Auxiliary Heat Performance (From Previous Calculation or from Table G) 23 Q99 Btu/yr-sf Com are Line D to Line E ,

Anytown, USA 70 AUXILIARY HEA T PERFORMANCE LEVEL

Worksheet II: The reference codes are shown Auxiliary Heat on Tables FI through F4 for Performance Level various types of solar systems. Worksheet II is used to estimate More information about the the savings from passive solar system types is provided in the systems and to estimate the discussion under Step C of this auxiliary heat performance level.. worksheet. The reference code This is the amount of heat that for the direct gain system is must be provided to the building "DGC 1" because night each year after the solar savings insulation is not proposed. The have been accounted for. reference code for the sunspace The example building has is "ssc 1" since all the sunspace two solar systems: direct gain glazing is vertical. south glazing and a sunspace. The south wall of the

South example building actually faces Step A. Projected Area of Projection 10° east of south because of site Passive Solar Glazing Projected Area of Passive Solar Glazing conditions. The adjustment The solar savings fraction is based on the The first step is to calculate the projected area of solar glazing. factor is therefore 0.98 for both projected area of the solar The worksheet allows the solar systems as selected from glazing. The proj ected area of user to enter the rough frame Table E. Each solar system area passive solar glazing is the area area of solar glazing. since it is is multiplied by the net area projected on a plane facing true generally easier to measure this. factor and the appropriate south (the actual glazing may be The rough frame area is adj ustment factor to calculate oriented slightly east or west of multiplied by a net area factor of the projected area. Both the true south). The projected solar 0.80 to account for window total projected area and the total . glazing also accounts for sloped framing and mullions. If the net area are summed at the bottom glazing in certain types of glass area is entered. the net of the table. sunspaces. area factor is 1.00. For most solar systems the Table E-ProJected Area The example building has Adjustment Factors projected area may be calculated two separate passive solar Degrees off ~solar System Type True D SSA SSB, by multiplying the actual glazing systems: direct gain and a South ,S SSD SSE area times an adjustment factor sunspace. This means that two o 1.00 0.77 0.75 5 c$? 0.76 0.75 taken from Table E. lines of the table must be 10 0.98 0.75 0.74 15 . 0.74 0.73 Alternatively. the projected completed. If the example 20 0.94 0.72 0.70 25 0.91 0.69 0.68 area may be determined by building had other types of solar 30 0.87 0.66 0.65 making a scaled elevation systems. for instance Trombe The last part of Step A is to drawing of the building. looking walls or water walls. additional divide the total projected area by exactly north. Surface areas lines in the table would be the conditioned floor area. giving may then be measured from the completed. the total projected area per scaled elevation drawing. This In the first column. the square foot. This value is used concept is illustrated in the reference code for each type of in Worksheet I. Step E to figure below. solar system is entered along determine the heating degree with a description of the system. day multiplier.

, ./

Anytown, USA PASSIVE SOLAR DESIGN STRATEGIES 71

Step B. Load Collector Ratio A reference code, for The solar savings fraction for The load collector ratio is instance "DGC 1", is also each system is multiplied by the calculated by taking the total provided for each solar system projected area and totaled at the heat loss from Worksheet I, Step variation. These references are bottom of the table. This total is D and multiplying this value entered on the worksheet "Solar then divided by the total times 24 (hours/ day) and System Reference Code". They projected area from Step A to dividing by the total projected are also a key to additional calculate the weighted average area of the solar glazing information about each solar solar savings fraction for the calculated in the previous step. system as provided in Passive whole building. Solar Heating Analysis and The solar savings fractions Step C. Solar Savings Fraction other reference manuals. are based on reference designs. The next step is to calculate the The assumptions made about solar savings fraction for the F1-Direct Gain these reference designs are Load DGCI DGC2 DGC3 building. This is calculated as a Collector Double Low-e R-9 Night summarized below. weighted average of the solar Ratio Glazing Glazing Insulation 200 0.10 0.11 0.13 savings fraction for the separate 155 0.13 0.14 0.17 Direct Gain 100 0.18 0.20 0.24 passive solar systems. The 80 0.22 0.25 0.30 The direct gain reference 60 0.28 0.31 0.38 weightings are based on 50 0.32 0.36 0.44 designs are all assumed to have projected area. 45 0.34 0.39 0.47 40 0.37 0.43 0.51 double-pane glass and sufficient The solar systems used in 0.47 0.56 heat storage to limit the clear 0.52 0.62 this step should be identical to ar ~. 9 0.58 0.69 day temperature swing to 13°F. 20 0.55 0.65 0.77 those used above in Step A. The 15 0.62 0.74 0.85 For the case with night first two columns are simply insulation, the thermal carried down from the first and F4-Sunspaces resistance is assumed to be R-9. Load last columns in· Step A. Collector sunsEace Type ) The solar savings fraction for Ratio SSAI SSBI SCI SSDI SSEI Trombe Walls 200 '0.17 0.14 0.11 0.19 0.15 e9-ch individual system is taken 155 0.20 0.17 0.14 0.23 0.19 The Trombe wall reference 100 0.26 0.22 0.19 0.30 0.26 from Tables F1 through F4 80 0.30 0.25 0.23 0.35 0.30 designs are all assumed to have based on the load collector ratio 60 0.35 0.30 0.28 0.42 0.36 50 0.39 0.34 0.32 0.46 0.40 double-pane glass. The mass calculated in Step B and the 45 0.42 0.36 0.35 0.49 0.43 wall is assumed to be 12 inches 40 0.44 0.39 0.38 0.52 0.46 type of solar system. Table F1 is 0.48 0.42 0.56 0.49 thick and constructed of for direct gain systems, Table F2 0.52 0.46 0.60 0.54 ~ 0.56 0.50 ~.0 0.65 0.59 masonry or concrete. for thermal storage walls, Table 20 0.62 0.56 0.57 0.72 0.65 15 0.70 0.64 0.65 0.79 0.73 F3 for water walls and Table F4 Water Walls for sunspaces. There are The water wall reference designs multiple columns in each table are all assumed to have double­ that account for system design pane glass. The water tank is features such as night assumed to be nine inches insulation or selective surfaces. thick, extending continuously in front of the glazing surface. The space between the water tank and the glazing is assumed to be sealed.

Anytownl USA 72 AUXILIARY HEA T PERFORMANCE LEVEL

Sunspaces Step D. Auxiliary Heat Data is provided for five Performance Level sunspace reference designs as The auxiliary heat performance illustrated on the following level is calculated by multiplying figure. Double glazing is the conservation performance assumed for all reference level from Worksheet I, Step E, designs. Reference designs times one minus the solar SSAl, SSB 1 and SSD 1 are savings fraction, calculated in assumed to have opaque end the previous step. This value walls. All are assumed to have a represents the amount of heat concrete or masonry floor about that must be provided to the six inches thick and a masonry building by the auxiliary heating or concrete common wall system(s). separating the sunspace from the living areas of the house. Step E. Comparative Auxiliary The glazing for designs SSAI Heat Performance and SSD 1 is assumed to be The calculated auxiliary heat sloped at an angle of 50° from performance level may be the horizon. The sloped glazing compared to the performance in designs B and E is assumed level for a typical basecase to be at an angle of 30°. building in the area. This may be taken from Table G and is 23,099 Btu/yr-sf.

\ ) I Alternatively, the performance level may be compared to a previous worksheet calculation made for a typical builder house. If the auxiliary heat performance level calculated in Step D were larger than the base case auxiliary heat performance, the designer should conSider increasing the size of the solar

Sunspace Reference Designs systems, adding additional solar Data is provided for five types of sunspaces. systems or increasing insulation levels.

\ /

Anytown, USA PASSIVE SOLAR DESIGN STRATEGIES 73

Worksheet III: Thermal Mass/Comfort ( \ A. Heat Capacity of Sheetrock and Interior Furnishings '\ ) Unit Total Heat Heat Floor Area Capacity Capacity

BQQIDl! lIlli!b Qi[~Q! !:aiilie 424 X 4.7 2H~1 QRiilQ~l! QQee~Q!~g !Q Qi~Q! !:aiilie QRiilQ~l! ~4~ X 4.5 = 42Z1 2452 Btu/OF Total B. Heat Capacity of Mass Surfaces Enclosing Direct Gain Spaces Unit Heat Mass Description capaci~ Total Heat (include thickness) Area [Table ] Capacity

nQIDb~ WslIIl! X 8.8 , wm~[Wiillll! X 10.4 = E~RQl!~g Qliilb ie Que lQa X 13.4 = laaQ E~RQl!~g Qliilb IlIQ! ie Que laZ X 1.8 = 24Z X = X = X = 122Z Btu/OF Total

C. Heat Capacity of Mass Surfaces Enclosing Spaces Connected to Direct Gain Spaces Unit Heat Mass Description Capacity Total Heat (include thickness) Area [Table H] Capacity I[QIDb~ WslIIl! . X 3.8 W~[WiillIl! X 4.2 = ) EiilQ~ 6[iQis 4" III X 3,Z = 4ll X = X = 4ll Btu/OF Total

D. Total Heat Capacity a4~Q Btu/OF (A+B+C)

E. Total Heat Capacity per Square Foot

a4~Q + 15Q4 = 52 Btu/OF-sf Total Heat Conditioned Capacity Floor Area

F. Clear Winter Day Temperature Swing Total Comfort Projected Area Factor [Worksheet II] [Table I]

Qi~Q! !:aiilie 2~ X a22 = 5~Z54 Quel!RiilQ~l! Q[ 12a X 2~~ = 4a zaz ~e!~g nQIDb~ WslIIl! lQa 4~1 + a4~Q = 12 a OF Total Total Heat Capacity G. Recommended Maximum Temperature Swing 13 OF ) Com are Line F to Line G

Anytown, USA 74 COMFORT PERFORMANCE LEVEL

Worksheet III: Step A. Heat Capacity of In the example building, the Thermal Sheetrock and Interior master bedroom, dining area Mass/Comfort Furnishings and kitchen are all direct gain This worksheet is used to The first step is to estimate the space.s. The secondary calculate the thermal effective heat capacity bedrooms, bathrooms and mass/comfort performance level, associated with low-mass master bedroom closet are which is the temperature swing construction and interior directly connected to the direct expected on a clear winter day furnishings. To complete this gain spaces. The utility room with the auxiliary heating step it is necessary that two and entry foyer are not system not operating. A high sub-areas be identified within conSidered in this calculation temperature swing would the building: those areas that since they are not connected to indicate that inadequate thermal receive direct solar gains and a direct gain space. These areas mass is provided in the building those areas that are connected are illustrated for the example design, which not only creates to rooms that receive direct solar building. discomfort but decreases solar gains. This is because the mass The direct gain space is heating performance. of sheetrock and furnishings multiplied by 4.7 and the spaces The general procedure of the located in direct gain rooms is connected to direct gain spaces worksheet is to calculate the more effective. Rooms that are are multiplied by 4.5. These effective heat capacity of mass separated from direct gain products are summed and elements located within the spaces by more than one door represent the effective heat conditioned space of the should not be included in either capacity associated with the building. The total effective heat category. sheetrock and interior capacity is then combined with furnishings. the direct gain projected area to estimate the clear winter day temperature swing. Note that ) thermal mass elements located within unconditioned spaces such as the sunspace are not included in this calculation.

1i)))1 Direct Gain Spaces Unconditioned Garage I,l@ililm Spaces Connected to Direct Gain Spaces moo Spaces Not Connected to Direct Gain Spaces

Suns pace

Building Sub-areas for Calculating Effective Heat Capacity Worksheet 11/ requires that the building be divided into sub-areas.

Anytown, USA PASSIVE SOLAR DESIGN STRATEGIES 75

Step B. Heat Capacity of Mass Exposed slabs-on-grade Step C. Heat Capacity of Mass Surfaces Enclosing include those with a surface of Surfaces Enclosing Spaces () Direct Gain Spaces vinyl tile. ceramic tile or other Connected to Direct Gain The heat capacity of thermal materials that are highly Spaces mass elements (other than conductive. Slabs that are The same type of calculation is sheetrock and furnishings) that covered with carpet should not performed for mass surfaces enclose the direct gain spaces is be considered to be exposed. that enclose spaces connected conSidered in this step. The The exposed slab area should be to direct gain spaces. The surface area of each element is further reduced. when primary difference is the unit measured from the building appropriate. to account for heat capacity figures taken from plans and multiplied by the unit throw rugs and furnishings. Table H2 instead of Table H 1. heat capacity. The unit heat The exposed slab area is In the example building. the capacity is printed directly in then subdivided into two areas: fireplace wall and hearth are the table for Trombe walls. water that which is expected to be in considered in this category. walls. and exposed slabs-on­ the sun and that which is not. This area and the unit heat grade. The unit heat capacity As a rule-of-thumb. slab area capacity is entered in the table for other mass elements is should be considered in the sun and multiplied by each other. selected from Table H 1. Note only when it is located directly This represents the total that thermal mass located in the behind south glazing. In any effective heat capacity of mass sunspace is not included in this event. the slab area assumed to elements that enclose the calculation. be in the sun should not exceed spaces connected to direct gain 1.5 times the south glass area. spaces. H1-Mass Surfaces Enclosing Direct Gain Spaces . In the example building. the Thickness (inches) slabs-on-grade located in the H2-Rooms with no Direct Solar Gain Material 1 2 3' 4 6 8 12 Thickness (inches) Poured Conc. 1.8 4.3 6.7 8.8 11.311.5 10.3 kitchen and dining room are Material 1 2 ~ 4 6 8 12 ) Conc. Masonry 1.8 4.2 6.5 8.4 10.210.0 9.0 located within direct gain Poured Conc. 1.7 3.0 3.6 3.8 3.7 3.6 3.4 Face Brick 2.0 4.7 7.1 9.0 10.49.9 9.0 Conc. Masonry 1.6 2.9 3.5 ~.6 3.4 3.2 Flag Stone 2.1 4.8 7.1 8.5 8.6 8.0 7.6 spaces. Some of this area is Face Brick 1.8 3.1 3.6 3.7 .5 3.4 3.2 Builder Brick 1.5 3.7 5.4 6.5 6.6 6.0 5.8 Fla~Stone 1.9 3.1 3.4 . 3.2 3.1 3.0 Adobe 1.3 3.2 4.8 5.5 5.4 4.9 4.8 considered to De in the sun and Builder Brick 1.4 2.6 3.0 3.1 2.9 2.7 2.7 Hardwood 0.4 1.4 1.8 1.7 1.5 1.5 1.5 Adobe 1.2 2.4 2.8 2.8 2.6 2.4 2.4 Water 5.2 10.415.6 20.8 31.241.6 62.4 the remainder not. These Hardwood 0.5 1.1 1.3 1.2 1.1 1.0 1.1 surface areas are entered in the table and multiplied by the appropriate unit heat capacity. The products are then summed at the bottom of the table.

Anytown, USA 76 COMFORT PERFORMANCE LEVEL

Step D. Total Heat Capacity Step F. Clear Winter Day Step G. Recommended The total heat capacity is the Temperature Swing Maximum Temperature Swing sum of the heat capacity from The clear winter day The comfort performance target '\ Steps A, B and C. This temperature swing is calculated for all locations is 13°F. If the ) represents the effective heat in Step F. The projected area of comfort performance level capacity of all thermal mass all direct gain glazing is entered calculated in Step F had been within the building. in the first row. This includes greater than 13°F, additional all direct gain systems either thermal mass should be added Step E. Total Heat Capacity with or without night insulation. to the building or direct gain per Square Foot In the second row, the projected glazing should be reduced. The total heat capacity area of sunspace glazing and calculated in Step D is divided Trombe walls vented to the by the total floor area of the indoors is entered. Unvented building to get the total heat Trombe walls and water walls capacity per square foot. The are not included in this floor area used in this calculation since solar gain from calculation should not include these systems does not the sunspace or other contribute to the temperature unconditioned spaces. This swing of the conditioned space. value is calculated here for The appropriate comfort convenience, but it is not used factor is entered in the second until Worksheet IV is completed. column, selected from Table I. ,(he projected areas are multiplied by the appropriate comfort factors and summed. '\ This sum is then divided by the ! total heat capacity from Step D to yield the clear winter day temperature Swing.

Table I-Comfort Fact~rBtu/sf) Direct Gain Suns paces and 99 Vented Trombe Walls

)

Anytown, USA PASSIVE SOLAR DESIGN STRATEGIES 77

Worksheet IV: Summer Coolin Performance Level A. Opaque Surfaces '\ Radiant Barrier Absorp- Heat Gain j Heat Loss Factor tance Factor Description [Worksheet I] [Table J] [Table K] [table L] Load

Q!2i1iDg:!lrQQf:! ~Q X j QQ X Q!lZ X !lZQ = !2!2~ lZ X j QQ X Q!I:Z X !lZQ = ~Z!2 X X X = W§II:! !lQ X na QZQ X 2!2~ = Z~!2 X na X = OQQ[:! ~fi X na Q~Q X 2!2~ = 2a jaQ~ kBtu/yr Total B. Non-solar Glazing Rough Frame Net Area Shade Factor Heat Gain Description Area Factor [Table M] Factor [Table L] Load

t!/Q[tb !:al~:!:! !lQ X 0.80 X Q!2Z X ~ZQ = ~~fi X 0.80 X X = ESI:!t !:a lSi:!:! !2 X 0.80 X QaQ X !2a ~ = ~~j X 0.80 X X = W!2:!t!:aI~:!:! !2 X 0.80 X QaQ X Z~2 = ~fij X 0.80 X X = Slsllligbt:! X 0.80 X X = X 0.80 X X = j!2ZZ kBtu/yr Total C. Solar Glazing Solar System Rough Frame Net Area Shade Factor Heat Gain \ Description Area Factor [Table M] Factor [Table L] Load ) Oi[!2Qt !:a~iD aa X 0.80 X Qa~ X fifiQ = ~2g X 0.80 X X = StQ[~g!2 llll~lI~ X 0.80 X X X 0.80 X X = S!.ID:!J2~Q!2 2Qa X 0.80 X Qa~ X j22 = j!2afi X 0.80 X X = !la~~ kBtu/yr Total D. Internal Gain

22fiQ +( ~!lQ X ~ = fiQZQ kBtu/yr Constant Variable Number of Component Component Bedrooms [Table N] [Table N] E. Cooling Load per Square Foot

1,000 X j~ !I!I~ + jfiQ!I a~!l2 Btu/yr-sf (A+B+C+D) Floor Area F. Adjustment for Thermal Mass and Ventilation No night vent with no ceiling fan Z~!2 Btu/yr-sf [Table 0] G. Cooling Performance Level a2Q!2 Btu/yr-sf (E -F) H. Comparison Cooling Performance (From Previous Calculation or from Table P) 9Z!2!2 Btu/yr-sf Com are Line G to Line H

Anytown, USA 78 SUMMER COOLING PERFORMANCE LEVEL

Worksheet IV: Table J-Radiant Barrier Factors The heat loss from each of Radiant Barrier Summer Cooling No Radiant Barrier .0 these elements is carried over Performance Level from Worksheet I. Note that the Worksheet IV is used to Table K-Solar Absorptances door heat loss is reduced by half . Color Absorptance calculate the summer cooling Gloss White since one of the two doors does performance level. This is the Semi-gloss White not receive sunlight. The Light Green heat that would need to be Kelly Green I proposed building does not have Medium Blue 0.51 removed from the bUilding by an Medium Yellow 0.57 a radiant barrier in the attic, so Medium Orange 0.5B air conditioner in order to Medium Green 0.59 the radiant barrier factor is 1.00. maintain comfort during the Light Buff Brick 0.60 Absorptances are selected based Bare Concrete summer. Red Brick on the exterior building colors Medium Red ~ The worksheet accounts for Medium Brown 0.B4 and the heat gain factors are Dark Blue-Grey O.BB four sources of cooling load: Dark Brown O.BB from Table L. opaque surfaces exposed to the sun, non-solar windows, passive Step B. Non-solar Glazing solar systems, and internal gain. Ceiling/roofs Cooling load associated with the Walls and Doors These loads are then adjusted to North Glass windows that do not face south, East Glass account for ventilation and West Glass i.e. those that are not part of one Skylights of the solar systems, is thermal mass .. Direct Gain Glazing Trombe Walls and calculated by multiplying the Water Walls Step A. Opaque Surfaces Sunspaces surface area in each orientation SSAl 39.3 Not all opaque surfaces SSBl times the net area factor, a contribute to the cooling load of SSCl .~ shade factor (from Table M) and SSDl the building: only those surfaces SSEl 39.3 a heat gain factor (from Table L). exposed to sunlight In the example building, four This calculation gives the (ceilings/roofs and walls) are lines of the table are completed, annual cooling load for each ) included in the calculation. For two for the ceiling/roof types, non-solar glazed surface. The each ceiling and wall surface one for the exterior walls with total for the building is the sum listed on Worksheet I and brick veneer and one for the of the cooling load for each exposed to the sun, the heat entrance door. The wall that surface. loss should be carried over to separates the house from the Table M-Shading Factors this worksheet along with a garage and the door in this wall Projection consistent description. This are not included, since they are Factor South st North 21 0.00 ~ . 1.00 . heat loss is then multiplied by a not exposed to sunlight. 0.20 . .93 ~ .93 . 4I1o,~ 0.40 . 3 ~0.B1 O.Bl • 1 9' c;1JC7 radiant barrier factor when 0.60 0.49 0.71 0.7 '67 0.6B O.BO 0.35 0.60 0.6f 0.56 appropriate (from Table J), the 1.00 0.30 0.50 0.54 0.45 absorptance (from Table K) and 1.20 0.24 0.40 0.46 0.3B a heat gain factor (from Table L). -... Multiply by O.B for low-e glass, 0.7 for tinted glass and 0.6 for low-e tinted Qlass. The end product of this The rough frame area is calculation is an estimate of the generally entered in the table annual cooling load that is and adjusted by the net area associated with each suIface in factor. If the net glazing area is thousands of Btu per year entered instead, then the net (kBtu/yr). area factor is 1.00.

Anytown, USA PASSIVE SOLAR DESIGN STRATEGIES 79

Table M gives the shade If the example building had Step C. Solar Glazing factor for overhangs. The tinted glazing. glazing films or The solar systems addressed on overhang shade factor depends external shading devices. the Worksheet II reduce heating on the orientation of the window shade factors from Table M energy. but they also can and the projection factor. The should not be used. Sunscreen increase cooling energy. The proj ection factor is the overhang and glass manufacturers cooling energy impact of the projection divided by the usually rate the shading effect of solar systems is calculated in distance from the bottom of the their devices by publishing a this step. Each solar system window to the bottom of the shading coefficient. The listed on Worksheet II should be overhang. as illustrated below. shading coefficient is a number carried over to this worksheet. between zero and one that The cooling energy for each A indicates how much solar heat system is calculated by makes it through the window multiplying the total surface compared to an unshaded 1/8 area (not the projected area) inch clear pane. This shading times the net area factor. the coefficient may be used in the appropriate shade factor (as calculation instead of the value discussed above) and a heat from Table M. gain factor (from Table L). This The overhang on the east calculation gives the annual and west is at the eave. well cooling load for each passive above the window. and does not solar system. Overhang Projection Factor provide any useful shading. For A shade factor of 0.83 is The projection factor is the overhang projection divided by the distance between the these windows. the shade factor used because of south bottom of the window and the bottom of the is 1.00. overhangs. This is based on a overhang. Each glazing area is projection factor of about 0.2 as \ The north windows have a multiplied by the net area factor discussed above. height of four feet and the and the appropriate shade The annual cooling load bottom of the overhang is about factor. The products are associated with all the passive six inches above the window summed at the bottom of the solar systems is summed at the head. The overhang projection table. bottom of the table. is 1.5 feet. The projection factor is calculated by dividing the overhang projection by the distance from the bottom of the window to the bottom of the overhang. This is about 0.33. A shade factor of 0.84 is used in the calculations. which is interpolated between the values for a projection factor of 0.2 and 0.4

Anytown, USA 80 SUMMER COOLING PERFORMANCE LEVEL

Step D. Internal Gains Step F. Adjustment for Step G. Cooling The last component of cooling Thermal Mass and Ventilation Performance Level load is from internal gain. The total cooling load calculated The summer cooling \ Internal gain is heat given off by in Step E is adjusted in this step performance level is calculated' ) lights, appliances and people. to account for the effects of by subtracting the adjustment Some of the cooling load thermal mass and ventilation. in Step F from the cooling load associated with internal gain is The adjustment depends on per square foot calculated in considered to be constant for all the total heat capacity per Step E. This is an estimate of houses regardless of the number square foot calculated on the amount of heat that must be of bedrooms or size. This is Worksheet III, Step E, but also removed from the building each because all houses have a depends on whether or not the year by the air conditioner. refrigerator and at least one building has night ventilation or occupant. Another component ceiling fans. The adjustment is Step H. Comparison Cooling of cooling load from internal entered in the blank in Step F. Performance gain is considered to be variable The cooling performance level Table 0-Thermal Mass and Ventilation for the proposed design may be and depends on the number of Adjustment (Btu/yr-sf) bedrooms. These components Total Heat Night Night No Night No Night compared to the base case Capacity Vent wI Vent wI No Vent wI Vent wI N are accounted for separately in per SF Ceil. Fan Ceil. Fan Ceil. Fan Ceil. Fan cooling performance level for the 0.0 4,250 400 2,320 -1,600 the calculation. 1.0 5,550 1,480 3,620 -520 area, given in Table P. 2.0 6,240 2,080 4,310 080 Both the constant 3.0 6,610 2,420 4,680 410 component and the variable 6,800 2,600 4,8 600 . 6,910 2,700 ,0 700 component are taken from Table 6.0 6,960 2,760 5,0 760 dP. 6,990 2,790 , 60 790 N. The variable component is 8.0 7,010 2,810 5,080 810 Alternatively, the cooling 9.0 7,010 2,820 5,080 820 multiplied by the number of 10.0 7,020 2,820 5,090 820 performance level may be compared to other building bedrooms in the house and Total heat capacity per square foot is calculated on added to the constant Worksheet III Ste E. designs conSidered by the ) component to yield the total The example building has a builder to be typical of the area. cooling load from internal gain. total heat capacity per square In this case, the worksheets foot of 5.6. It has neither night would first be completed for the ventilation nor ceiling fans. typical design and the results of Constant Component Variable Component Night ventilation is a these calculations would be building operation strategy entered in Step H. Step E. Cooling Load per where windows are opened at If the cooling performance Square Foot night when the air is cooler. level of the proposed building This step sums the cooling load The cool night air allows heat to (Step G) is greater than the base associated with opaque escape from the thermal mass case or typical-design surfaces, non-solar glazing, elements in the building. The conservation performance level, passive solar systems and cooler thermal mass elements the designer should conSider internal gain (Steps A, B, C and help keep the building measures to reduce the cooling D). The sum is then divided by comfortable the following day performance leveL Such the floor area of the building when air temperatures rise. measures might include and multiplied by 1,000 to reducing non-solar glass, convert the cooling energy into providing additional shading or terms consistent with the base increasing thermal mass. case cooling performance.

Anytown, USA Passive Solar Design Strategies APPENDIX

Passive Solar Industries Council National Renewable Energy Laboratory Charles Eley Associates With Support From: U.S. Department of Energy PASSIVE SOLAR DESIGN STRATEGIES 81

Passive Solar: a whole building design Suntempering: an increase of south­ Glossary and construction techniques which help facing glass to about 7 percent of a total a building make use of solar energy by floor area, without additional thermal non-mechanical means, as opposed to mass beyond the "free" mass already in a active solar techniques which use J¥pica1 house -- gypsum wall board. Auziliary H_tiDg System: a term for eqUipment such as roof-top collectors. framing, conventional furnishings and the system (gas, electric, oil, etc,) which floor coverings. provides the non-solar portion of the house's heating energy needs, referred to Phase-Change Materials: materials such as the "auxilaIy heat." as salts or waxes which store and release Temperature Swing: a measure of the energy by changing "phase". Most store number of degrees the temperature in a energy when they turn liquid at a certain space will vaty during the course of a British Thermal Uait (Btu): a unit used temperature and release energy when sunny winter day without the furnace to measure heat. One Btu is about equal they turn solid at a certain temperature: operating; .an indicator of the amount of to the heat released from bunrlng one some remain solid but undergo chemical thermal mass in the passive solar kitchen match. changes which store and release energy. system. Phase change materials can be used as Conservation: in addition to energy thermal mass, but few products are Thermal Mass: material that stores conseIVation in the general sense. the commercially available at this time .. energy, although mass will also retain term is used to refer to the non-solar, coolness. The thermal storage capaciry­ energy-saving measures in a house Purchased Energy: although the terms of a material is a measure of the which are primarily involved with are often used interchangably, a house's material's abiliry- to absorb and store improving the building envelope to guard "purchased energy" is generally greater heat. Thermal mass in passive solar against heat loss -- the insulation, and than its "auxilaIy heat" because heating buildings is usually dense material such air infiltration reduction measures. systems are seldom 100% efficient, and as brick or concrete masonty, but can more energy is purchased than is also be tile, water, phase change Direct Gain: a passive solar energy actually delivered to the house. materials, etc. system in which the sunlight falls directly into the space where it is stored R-Value: a unit that measures the Thermal Storage Wall: a passive solar and used. resistance to heat flow through a given energy system also sometimes called material. The higher the R-value, the Trombe Wall or indirect gain system; a Glazing: often used interchangeably with better insulating capabiliry- the material south-facing glazed wall. usually made of window or glass. the term actually refers has. The R-value is the reciprocal of the masonty but can also be made of to specifically just to the clear material U-factor. containers of water. . which admits sunlight, and so can also be plastic. Double and triple glazing Radiant Barrier: reflective material used Trombe Wall: a thermal storage wall. refer to two or three panes. in hot climates to block radiant heat, referred to by the name of its inventor. particularly in a house's roof. Dr. Felix Trombe. Indirect Gain: a passive solar system in which the sunlight falls onto thermal Shading Coefficient: a measure of how U-Factor: a unit representing the heat mass which is pOSitioned between the much solar heat will be transmitted by a loss per square foot of surface area per glazing and the space to be heated, i.e. a glazing material, as compared to a single degree OF of temperature difference (see Thermal Storage Wall or Trombe Wall. pane of clear uncoated glass. which has R-value above). a shading coefficient (SC)· of 1. For LoW-Emissivity: the term refers to a example. clear double-pane glass might surface's abiliry- to absorb and re-radiate have an SC in the range of .88. heat. A material with a low emissiviry­ Reflective glass might have SC's of .03- absorbs and re-radiates relatively small .06. In general. lower shading amounts of heat. Low-emissiviry- or "low­ coefficients are desirable when heat gain e" glass sandwiches a thin layer of is a problem. metallic film or coating between two panes of glass. The low-e glass blocks Sunspace: passive solar energy system radiant heat, so it will tend to keep heat sometimes also referred to as an isolated energy inside the house during the gain system. where sunlight is collected winter, and keep heat energy outside the and stored in a space separate from the house during the summer. living space, and must be transferred there either by natural convection or by fans.

Green Bay. Wisconsin 82 SUMMARY FOR GREEN BA Y, WISCONSIN Example Tables

Examples of Heat Energy Savings Examples of Heat Energy Savings Added Insulation Passive Solar-Direct Gain 1,500 sf Single Story House 1,500 sf Single Story House

Base Base Case 40% 60% 20% Case 20% 40% 60% R-values R-values Ceiling/Roof 31 37 46 65 Ceiling/Roof 31 35 43 56 Walls 19 23 28 41 Walls 19 22 27 35 Basement Wall 11 13 17 26 Basement Wall 11 13 16 21 Glass 1.8 1.8 2.7 3.3 Glass 1.8 1.8 2.7 3.3

Air ChangesIHour 0.50 0.37 0.34 0.26 Air ChangesIHour 0.50 0.43 0.40 0.28

Glass Area (percent of total floor area) Glass Area (percent of total floor area) West 3.0% 2.0% 2.0% 2.0% West 3.0% 2.0% 2.0% 2.0% North 3.0% 4.0% 4.0% 4.0% North 3.0% 4.0% 4.0% 4.0% East 3.0% 4.0% 4.0% 4.0% East 3.0% 4.0% 4.0% 4.0% South 3.0% 3.0% 3.0% 3.0% South 3.0% 7.5% 9.2% 12.0%

Percent Solar Savings Added Thermal Mass 3% 5% 7% 9% Percent of Floor Area 0.0% 3.1% 13.3% 30.0%

Performance (Btu/yr-sf) Solar System Size (square feet) Conservation 52,730 44,244 33,919 23,534 South Glass 45 112 138 180 Auxiliary Heat 50,890 41,735 31,556 21,342 Added Thermal Mass 0 46 199 450 Cooling 5138 2135 1265 324 Percent Solar Savings 3% 11% 16% 23%

Performance (Btu/yr-sf) Conservation 52,730 47,239 37,492 27,791 Auxiliary Heat 50,890 41,713 31,505 21.255 Examples of Heat Energy Savings Cooling 5,138 2.700 1.970 1,439 Suntemperect 1,500 sf Single Story House Summary: Insulation and tightness have been increased. South- facing glazing has been substantially increased. For these Base examples, added mass area is assumed to be six times the added Case 20% 40% 60% south alass area. R-Values Ceiling/Roof 31 36 44 60 Walls 19 22 27 38 Basement Wall 11 13 16 23 Glass 1.8 1.8 2.7 3.3

Air ChangesIHour 0.50 0.42 0.37 0.26

Glass Area (percent of total floor area) West 3.0% 2.0% 2.0% 2.0% North 3.0% 4.0% 4.0% 4.0% East 3.0% 4.0% 4.0% 4.0% South 3.0% 6.7% 6.7% 6.7%

Solar System Size (square feet) South Glass 45 100 100 100

Percent Solar Savings 3% 10% 12% 16%

Performance (Btu/yr-sf) Conservation 52,730 46,732 36,139 25,497 Auxiliary Heat 50,890 41,719 31,522 21,298 Cooling 5,138 2,556 1,556 564

Summary: Insulation values and tightness of the house (as measured in ACH) have been increased. The window area has been slightly decreased on the west, increased slightly on the east and north, and increased significantly on the south.

Green Bay, Wisconsin PASSIVE SOLAR DESIGN STRATEGIES 83

Examples of Heat Energy Savings Examples of Heat Energy Savings Passive Solar-Sunspace Passive Solar-Thermal Storage Wall 1,500 sf Single Story House 1,500 sf Single Story House

Base Base Case 20% 40% 60% Case 20% 40% 60% R-Values R-Values Ceiling/Roof 31 34 41 53 Ceiling/Roof 31 34 40 49 Walls 19 21 25 33 Walls 19 21 25 31 Basement Wall 11 12 15 19 Basement Wall 11 12 15 18 Glass 1.8 1.8 1.8 3.3 Glass 1.8 1.8 1.8 2.7

Air ChangesIHour 0.50 0.47 0.29 0.29 Air ChangesIHour 0.50 0.45 0.31 0.28

Glass Area (percent of total floor area) Glass Area (percent of total floor area) West 3.0% 2.0% 2.0% 2.0% West 3.0% 2.0% 2.0% 2.0% North 3.0% 4.0% 4.0% 4.0% North 3.0% 4.0% 4.0% 4.0% East 3.0% 4.0% 4.0% 4.0% East 3.0% 4.0% 4.0% 4.0% South (windows) 3.0% 3.0% 3.0% 3.0% South 3.0% 3.0% 3.0% 3.0% Sunspace 0.0% 6.4% 8.9% 13.0% Thermal Storage Wall 0.0% 7.3% 11.1% 17.0%

Solar System Size (square feet) Solar System Size (square feet) South Glass 45 45 45 45 South Glass 45 45 45 45 Sunspace Glass 0 96 132 195 Thermal Storage Wall 0 109 166 255 Sunspace Thermal Mass 0 289 398 586 Percent Solar Savings Percent Solar Savings 3% 15% 23% 35% 3% 16% 21% 29% Performance (Btu/yr-sf) Performance (Btu/yr-sf) Conservation 52,730 49,560 41,300 32,826 Conservation 52,730 50,040 40,226 29,924 Auxiliary Heat 50,890 41,712 31,472 21,200 Auxiliary Heat 50,890 41,667 31,447 21,176 Cooling 5,138 2,312 1,368 566 Cooling 5,138 3,005 2,298 1,754 Summary: In the case of a Thermal Storage Wall, south-facing Summary: Insulation and tightness have been increased. North and glazing and thermal malis are incorporated together. The estimates east-facing glazing have been increased slightly. The sunspace here assume a 12-inch thick concrete Thermal Storage Wall with a assumed here is semi-enclosed (surrounded on three sides by selective surface and single glazing. conditioned rooms of the house, as in Figure SSD1 of the worksheets), with its south glazing tilted at 50 degrees. The common wall is a thermal mass wall made of masonry. Sunspace glazing is assumed to be double.

Cooling Potential

Basecase 5,138 Btu/yr-sf

Energy Savings Percent Strategy (Btu/yr-sf) Savings

No Night Ventilation 1 without ceiling fans 0 0% with ceiling fans 1,740 34

Night Ventilation 1 without ceiling fans 930 18 with ceiling fans 2,540 49

High Mass2 without ceiling fans 420 8 with ceiling fans 380 7

1 With night ventilation, the house is ventilated at night when temperature and humidity conditions are favorable.

2A 'high mass' building is one with a thermal mass area at least [eQual to the house floor area.

Green Bay. Wisconsin TECHNICAL BASIS Annual Heat Loss Central Ave. Unit B-1. Boulder. CO Technical Basis for 80301. (Worksheet I) the Builder 2. J. Douglas Balcomb. Robert W. Jones. Guidelines The heat-loss calculation is based on a Robert D. McFarland. and William O. straightforward summation of the Wray. Passive Solar Heating Analysis. traditional elements that make up the American Society of Heating. building heat-loss coefficient (excluding Refrigerating. and Air-Conditioning the solar components). The worksheet Engineers. 1984. Available from How the Builder procedure estimates the annual heat loss ASHRAE. 1719 Tullie Circle. NE. Atlanta. Guidelines Were by multiplying the heat-loss coefficient GA 30329. Produced by annual degree days (times 24 to convert from days to hours). Degree days 3. J. Douglas Balcomb and William O. for each month were determined using Wray. Passive Solar Heating Analysis. The text of the Builder Guidelines book is an appropriate base temperature that Supplement One, Thermal Mass Effects generated by merging two computer files. accounts for an assumed thermostat and Additional SLR Correlations. The first is a word-processor file setting of 70 degrees. an assumed American Society of Heating. containing the text; it does not change internal heat generation of 36 Btu/ day . Refrigerating. and Air-Conditioning from location to location. The second per sq ft of floor area. and the total Engineers. 1987. See ASHRAE address contains numbers and text and is building loss coefficient. This forms the above•• ~: location dependent. This second file is basis of the table of heating degree day produced by running a computer multipliers. The result of the worksheet program that calculates perfonnance is an estimate of the annual heat Temperature Swing numbers based on long-term monthly required to maintain comfort. excluding III) weather and solar data compiled by the both positive and negative effects (Worksheet National Oceanic and AtmospheriC resulting from the solar components. In Administration for a particular location. this estimate. no solar heating credit is The temperature swing estimate on The merge operation slots the numbers given to east, west. and north windows. wOI'Iq,heet III is based on the diurnal and text in the second file into their because it is assumed that these will be heat capacity (dhc) method (reference 3). correct locations in the first file. This is protected by vegetation or other shading The method is an analytic procedure in. then laser printed to produce the in accordance with the Builder Guideline which the total heat stored in the camera-ready manuscript. recommendations. This is a conservative building during one day is estimated by assumption because there will always be summing the effective heat storage some solar gain through these windows. potential of the all the various materials More than a Decade of in the building for a 24-hour periodic Experience cycle of solar input. Rooms with direct Annual Auxiliary Heat gain are assumed to have radiative (Worksheet II) coupling of the solar heat to the mass. The concentrated effort of research. Rooms connected to rooms with direct design. construction. monitoring. and gain are assumed to have convective evaluation of actual buildings that The tables of passive solar savings coupling. which is rather less effective. started at the First Passive Solar fractions are calculated using the solar especially for massive elements. The dhc Conference in Albuquerque in 1976 has load ratio (SLR) method (references 1 and of the sheetrock. framing. and furniture continued up to the present. It is 2). Monthly solar savings fraction (SSF) is approximated as 4.5 or 4.7 Btu/OF per estimated that more than 200.000 values are determined using correlation sq ft of floor area. Worksheet Tables HI passive solar homes have been built in fits to the results of hourly computer and H2 list the increased value of diurnal the United States during this time. This simulation calculations for a variety of heat capacity for various conventional wealth of experience' has been reviewed climates. These 12 values are converted materials that are often used to provide by NREL. the Technical Committee of into an annual value and entered into extra heat storage; assuming these PSIC. and by the Standing Committee on worksheet Tables FI-F4. The SLR method niateri3.ls replace sheetrock. Energy of the National Association of gives answers that agree within about Home Builders and is distilled into these 5% of the hourly computer simulations Guidelines. and within 11 % of the measured passive solar performance of 55 buildings monitored under the Solar Buildings Analysis Pr~cedures Program. The SSF estimates account properly for both solar gains and heat The analysis procedures used throughout losses through the solar aperture and. the Guidelines were developed using thus. correct for omitting the solar simple. well-established methods for components from the calculation of estimating the performance of passive annual heat loss. solar heating and natural cooling strategies. These procedures (described 1. J. Douglas Balcomb. Robert W. Jones. below) were developed at the Los Alamos Robert D. McFarland. and William O. National Laboratory with funding from Wray. "Expanding the SLR Metlwd". the U.S. Department of Energy Solar Passive Solar Journal. Vol. 1. No.2. Buildings Program. See the references for 1982. pp. 67-90. Available from the more information. American Solar Energy SOciety. 2400

Green Bay. Wisconsin PASSIVE SOLAR DESIGN STRATEGIES

The only numbers in worksheet ill temperature is less than 62 OF. This Getting Data that are location dependent are the restriction avoids ventilation when high comfort factors. taken from Table I. The hUmidity might cause discomfort direct-gain comfort factor is 61 % of the Heating and cooling degree-day data can be obtained from the National Climatic solar gain transmitted through vertical. 4. Robert D. McFarland and Gloria south-facing double glazing on a clear Center. Asheville. NC. Refer to Lazarus. Monthly Auziliary Cooling Climatography of the United States No. Janmuy day. The driving effect of Estimation for Residential Buildings. sunspaces and vented Trombe walls is 81 which lists monthly normals for the lA-11394-MS. Los Alamos National period 1951-1980 on a state-by-state assumed to result in one-fuird this value. Laboratory. NM 87545. 1989. based on data from monitored buildings. basis. More than 2400 locations are The origin of the 61 % factor is described listed in this data base. in the references. Notfor Sizing Equipment

Annual Auxiliary Cooling All heating and cooling values given in the Builder Guidelines Tables and (Worksheet IV1 numbers calculated using the worksheets are for annual heat delivered or removed The purpose of including the summer by the mechanical heating or cooling cooling estimates in the Builder system. You cannot directly use these Guidelines is to (1) determine ifdesign numbers for sizing the capacity of this elements added to promote passive solar equipment. The methods developed by heating will cause excessive summer the American SOCiety of Heating. cooling loads and (2) provide a rough Refrigerating. and Air Conditioning estimate of the effectiveness of solar Engineers for sizing equipment are well­ shading and natural cooling strategies. established and are recommended. The The analysis method is based on a purpose of the guidance provided in modified monthly degree-day procedure these booklets is to minimize the in which the day is divided into daYAand operating time and resources consumed night periods (reference 4). All estimates by this equip~ent. are derived from correlations based on hourly computer simulations. Solar; conduction. and internal gains are Using the Worksheets in' estimated for each half-day period in Nearby Locations each month. Delay factors are used to account for heat carryover from day to The applicability of worksheets I and Il night and night to day. The results are can be extended somewhat by using the estimates of annual sensible cooling base-65 OF degree-day value for a site delivered by the air conditioner and do which is close to the location for which not include latent loads. the worksheet tables were generated. We Because the the original Los Alamos recommend limiting such applications to monthly procedure is too complex to be sites where the annual heating degree­ implemented in a worksheet. a simplified days are Within plus or minus 10% of the procedure is adopted on worksheet N. parent location and where it Heat Gain Factors and Internal Gain is reasonable to assume that the solar Factors in Tables L and N are the radiation is about the same as in the calculated annual incremental cooling parent location. The procedure is simple: loads resulting from a one-unit incremental change in the respective Use the measured base-65 OF degree-day heat input param!

Green Bay, Wisconsin