'Radiation Arkansas;'Solar Heaters. Be Attached,To

.DOCUMENT RESUME

ED 222. 385 SE-949 489

1 AUTHOR Skiles, Albert; Rose, Mary Jo 'TITLE Arkansas,Solar Retrofit.Guide. Greenhouses, Air' Heaters and Water Heatets. INSTITUTION. Arkansas State Energy Office, Little Rock. SPONS AGENCY. Department of EnergylWashington, D.p.; Ozarks .q Regional Commission, Little Rock, Ark. PUB DATE Jun 81 NOTE 109p.

EDRS PRICE' MF01/PC05 Plusi(Postage. DESCRIPTORS *Building Plans; Climate Control; *Constructi.on '(Procesd); Censtructiott Costs; Energy; ,*Greenhouses; -5-- *Heating; Resource Materials; Site SelectiOn; *Solar- 'Radiation IDENTIFIERS *Arkansas;'*Solar Heaters.

1-ABSTRACI -Solar retrofitS-are devices of Structures designed to' be attached,to existing buildingsAO Augmehttheir existing heating sources with solar energy.-An investigationq>f how solariretrofits should be desigeedto suit, the climate and resources of Arkansas is the'subject of this report.. FollOwing an introduction (sectiOn 1); section 2 focuses on solar greenhouses. Topics discuised'incldee.:the nature of 'Solar greenhouseS,-site reguiiementS and coSts, sun motion and orientation, greenhouse-house connection, glazing, heat storage., winter/summer temperaf4re control, greenhouse vardeting, and construCtion notes.,Case studieS'are also provided.. Section 3 focuses on the fUndamentals of.:solar air heaters, including, modular solar'air'

4, heaters, performance, and design methodt. SeCtion 4, foCusing on, batch solar Water heaters, includes an introduction, brief history, design, performance, and.limitations. Appendices include a glossary, referenCes for solar greenhouses; air heaters and water heaters, lists of solar periodicals and solar infoiMation sources, and solar radiation data .(incruding maps for each month7, evaluation of.solar radiation maps, and suCh technical ihfOrmatiOn as:tilt factors foi various regions,of'Arkansas) -(Author/JN)

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°ARKANSAS ENEIVY OFFICE ONE CAPITAL MALL LITTLE ROCK. RKANSAS

- 72201 +

Written and Illustrated by Albert SkIles Research assjétante by Mary Jo Rose

This book was published with funds provided by the United States Department of Energy and the Ozarks Regional.Cdmmission. *t , The statements, findings, cdnclusions, iecommendations, and'other information in this book are solely those of the authpr and do ndt neceilrily reflect the views of the Commission, the Com- mission's Energy Advisory Panel, or the UnitStates Department ot Energy.

3 TABLE'OFCONTENTS

I. INTRODUCTION 1

II.SOLAR GREENHOUSES A.What is a Solar Greenhouse9 4 B. Site Requirements and Costs 7 C. Sun Motion and Orientation 9 D. Greenhouse - House Connection 10 E. Glazing 13 F. Heat Storage 18 G.Wintertime Temperature Control 20

- H. Summertime Temperature Control 22

I. Greenhouse Gardening 1 27 J. Construction Notes 33 K. Case Studies 44,

III..SOLAR AIR HEATERS

A. Fundamentals 0 51 B. Modular Solar Air Hedters 54 C. Performance 56 D. Design Metho.ds 57

IV. BATCH SOLAR WATER HEATERS A.Introduction 59 B. A Brief History 61 Q. New Design 62 D. Performance 64 E. Limitations 65

Appendix A Glossary 66 Appendix B Solw Greenhouse References. 73 Appendix C Solar Air Heater References 76 Appendix D Solar Water Heater References. .77 Appendix E Solar Periodicals Appendix F Solar Information Sources 79 Appendix G ,Solar Radiation Data 80 INTRODUCTIQN

The concept ot using the sun to admit and trap solar energy, thus heat buildings is an ancient one. The greatly reducing the need/for conven- `emergence of "solar architecture" is tional heating fuels. Oyerhangs above not scomuch the birth of a new tech the windows shaded the structures nology as a rebirth of age-old prin-- from the high ommer sun. Entry- ciples. As in the past, the reason for ways were recessed to protect them this re-emergence is the high cost of from winter winds. The concept of de- fuel. signing buildings in responss to The scarcity of trees, which were natural ,climatic forces became com- the primary source of heating fuel in monplace. ancient Greece, prompted that cul- Today, with our growing scarcity of ture to utilize solar energy in dramatic fossil fuels, we find ourselves in a ways. Entire cities were oriented to situation similar to earlier civiliza- the, south to take advantage of the tions. About one-third of all energy low winter sun. Solar laws were en- consumed in the U.S. is used to heat acted that prevented the construction and cool buildings. We have to import of a building if it would shade adjacent one-third of our petroleum, which buildings during the winter months. everybody knows is getting more Similar laws are MIN being considered scarce and more expensive. We have in America. designed nearly all of our _buildings The Romans also had difficulty with the notion that our energy supply finding enough wood for heating fuel would be forever cheap and plentiful. because they used most of their Architects and planners were not wood to build ships. Gradually, the concerned with the orientation of high cost of importing wood from dis- buildings to the sun or with'' insula- tant places prompted the Romans to tion because the cost of heating and find solar solutions to their heating cooling was so low. The era of cheap needs. When the Romans began to energy is over, but we are stuck with use glass as a window material, solar all those inefficient buildings that re- architecture took a giant leap forward. quire enormous amounts of mechan- Many public and private buildings ical power (i.e., fossil fuels) to be Shad large south-facing windows to comfortable. Energy conservation is an obvious local workshops held around the way to reduce energy demand and is state that individuals can easily learn much easier, and more economical to construct the devices. A variety of than drilling for more oil -or gas or solar retrofits have also been de- mining more coal. However, after veloped by. other organizations, in- energy conservation measures have cláding Crowley's Ridge Develop- been taken, many buildings can be ment Council, Crawford-Sebastion economically adapted to utilize solar Community Developrnent,Council, energy for space heating or water and the Northwesk Arkansas Econom- heating purposes. Solar relrofits are ic Development District. What remains devices or structures designed t6 be to be developed is,a broad understand- attached to existing buildings to aug- ing of this simple technology among ment their existing heating sources Arkansans. with solar energy. The investigation Most people in Arkansas already of how solar retrofits should be de- feel that solar energy should play a signed to suit the climate and re- strong roll.in their energy future. This sourceS of Arkansas is the subject of was indicated by the Arkansas this report, Energy/Environmental Survey 1980, The solar retrofits examined during by Dr. John S. Miller, Jerry Donoho this project were greenhouses, air and Marvin Orndorff of the University heaters, and water heaters. They, all of Arkansas at Little Rock, in which hdtce several things in common other 401 families from throughout the than being "added on" to a building: state were interviewed. A convincing 1. Through theresearch and 85% of those surveyed favored mOre demonstration programs of, the Ari- solar development, while only 28% kansas Energy Office and several favored, additional nuclear power community organizations throughout plants: the state, the solar retrofits have The Arkansas Solar RetrofittGuide been tested and proven to be cost- was written to take the mystery out of ef fective in Arkansas. solar energy for those who want to 2. Alt, are built from locally avail- use itin their homes or businesses able building materials and require but do not know how. A composite of only basic carpentry and/or plumbing successful construction and opera- skills to conetruct. This puts them tion methods is presented in a format within reach of many low and middle tohelpindividuglsbuildsolar income people. retrofits for themselves. Also,itis 3,2All of the retrofits qualify the 'hoped that local businesses will be owner for a 40% federal income tax encouraged to offer solar retrofits as credit and a 100% state income tax an extension of their existing eer- deduction. vices. For instance, carpenters and The majoIrity of solar retrofit dem- contractors could offer solar green- onstration projects in Arkansas have houses, plumbers could build solar been funded through CETA training water heaters, and heating contrac- programs, the Ozarks Regional Com- tors could build solar air heaters. mission, and the Renewable Energy These professions already have all Grant Programs of the Arkansas the technical skills necessary to build Energy Office and the U.S. Departiu solar retrofits; they only need to learn ment of Energy. Agencies such as the how easy and profitable the devices Office of Human Concern of Rogers would be to build and install. and Community Energy Futures of , Two other publications that are Little Rock have demonstrated in companion texts to this report have

2 been published by the Arkansas sas, including solar radiation data Energy Office.1 The flrst text, Solar that is useful for designing any solar Greenhouses ih Arkansas, presents a application. This solar radiation 'data, general overview of solar greenhouse developed by Dr. Dan Turner and I.H. concepts. The second text, Arkan- Battle of the University of Arkansas at sas Climate Atlas, illustrates in map Fayetteville, has been included in form the weather statistics of Arkan- this report as Appendix G.

7 3 II.SOLAR GREENHOUSES

A: WHAT IS A SOLAR GREENHOUSE?

Like all greenhouses, a solar green- wall of the house, allowing excess house is a sunny room well suited for, heat to flow from the greenhouse to growing plants. However, a conven- the house. tional greenhouse with glass on all 4. Heat storage materials such as sides needs a heating source other rocks, containers .of water, or con- than the sun to keep tt warm during crete blocks are included in the the winter. The solar greenhouse greenhouse to absorb heat from the relies only on the sun to Iceep itself qun during the day and slowly release Warm and actually produces excess it at night to keep the space warm. heat that can be used to help warm a 5. The east and west walls, roof, house or other building. and foundation are well\insulated to The solar greenhouses described further reduce heat losses. in this report are Called "attached" By orienting the greenhouse to solar greenhouses because they are take advaniage of natural climatic built onto an existing building. They forces, it can,be heated entirely by differ from a conveintional green- solar energy. Proper design of the house in several other ways: thermal storage and ventilation will 1. Most of the glass or other glaz- ensure adequate light and tempera- ing is on the south side, where it col- turelevels for 'year-round plant lects more energy during the day than growth. it loses at night. In winter, the solar greenhouse 2. A double layer of glazing is traps as muth solar energy as pos- often used to reduce heat losses at sible. Some of ihis heat is absorbed night. by the thermal storage and some is 3. The north wall of the solar distributed by natural air convection greenhouse is attached to the south or a fan through openings to the I.

&' FIG. A-1

hou6e during sunny winter days. The tuce and spinach during the siimmer greenhouse also serves a valuable es well as in winter. function as an insulator to reduce heat loss from the house to the out- This project concerns the appropri- doors at night. ate design, construction, and opera- In summer, conventional green- tion of solar greenhoUses for Atkan- h,ouses require hugefanslito keep sanS who, will use them for both food cool, whereas solar greenhouses uti- and heat. The designs will be some- lize non-mechanical shading .and what different hor people who,want to ventilation techniques. Vents to the use the room for heating purposes outside are opened and shading de- only and not for groiting plants. This vices are used to keep the space cool. type of retrofit is called a "sunspace" The thermal storage also helps to or "sun room" which could be de- keep summer temperatures low by signed as an entryway, recreation absorbing any excess heat within the room, garage, and so forth. Both sunspaces and solar green- space. In fact, a properlydesigned fsk,' solar greenhouse will be able to pro- houses trap solar heat and distribute duce cool weather crops such as let- that heat through openings to the

59 WINTER Air heated by the sun in the greenhouse flows into the house through tipper openings; at the same time, cooler air is drawn from the house through lower openings. Afan maY be used td increase the efficiency of the systerh.

HOT AIR EXHAUST

SUMMER Vents exhaust warm air from the greenhouse, and lowlevel windows admitcooling si breezes,

FIG. A-2 house, but a solar greenhouse re- Growing beds and shelves are often quires more insulation and thermal installed as an afterthought, resulting storage. to keep the plants warm at in a very inefficient use of the space. night. Also, specific lighting require- This can prove to be a costly mistake ments for the plants and efficient ar- if you are planning to grOw plants for rangement of planting beds need to food or for sale. Fig. A-3 ill.ustrate$ be considered in a.solar greenhouse. common elements found insolar A solar greenhouse does more than greenhouses. collect solar energY to help heat the house; it also, must be designed to meet the particular light and tempera- FIG. A-3, Next Page : ture requirement of plants. The most 1. outer glazing, 2. inner glazing, 3. knee wall .comenon error in solar greenhouse windows, 4. concrete foundation, 5, ground- design is the lack of planning for how level plant bed, 6. 'gravel floor, 7, masonry and where plants will be grown. steps, 8, elevated plant bed, 9/tiouse Interior

SITE REQUIREMENTS AND COSTS

Before you begin to b.uild a solar work carefullY to make Simple mea- greenhouse, you should understand: surements, hammer and saw straight, and caulk and paint neatly. 1. The solar breenhouse 'must face within 30 degrees of true south. 5. Greenhouses .require consistent maintenance, including' planting, 2. The site should be relatively watering and harveSting plants, operf- free from shading by other buildings, ing and closing vents, and watching other parts of the house, or evergreen for pests. trees. Trees that lose their leaves in the fall (deciduous) are ideal to have 6. The average cost of a typical 8 close to the greenhouse. x 16 foot greenhouse aS described in this report is $700. ($5.46 per square 5. Openings such as doors or foot) if it is owner-built. 1\f you hire a windows are needed on the south carpenter to build the greenhouse, wall of the house ,where the green- expect to pay\ibout tWice that house will be attached so that air can amount. This figure Is based upon the circulate to anii from the house. If no assumption that all materials will be openings exist', you will h ve to make bought at 1981 retail prices. V ,,you openings into the wallor this pur- can use recycled materials or find a. pose. good bargain on glass at an auction , . or salvage yard, the cost could be 4. You do not need to be a piofes- much less. sional carpenter, but you will need to It I `111- II I, ninth., 1mm 1, ... r WilMt VilVeinnie-IPAIZZOMIKIP_Mb 41191141 11I11 i atkvo, I Ott 'dorm le;^=.1

1 I 1 I I NI INI P 111 I I wsr/ Linummiraisrmer r /gr..q11111j1 twO SeA,Airt C1*--- A 4k4ka 2X:444 14, ) :21 11 I 21,1" I r r or .!ii,,ere,, r ------c-1. fte..,s'S;;11% ,44--=7, pr nrz:21:3.7 .I.4;-1'#7 r 0 (2) 48 .._Ir.4tyoNe.; r ..t. ,.p,.... -,' ...... \ -S / 4 C. SUNMOTIoN AND ORliNTATION

SUMMERSUN WINtER SU14 JUNE 22 DEC. 22 78 DEGREES 32 DEGREES ABOVE HORIZON- ABOVE HORIZON

C-1

In order to design any solar device cal or tilted south wall receives very properly,itis necessary to under- little dieedt suri on a summer day, stand how the sun moves across the white east and west walls and roofs sky! 'Everyone knows that the sun, receive several times as much sun. rises in tfte east, moves across the In the spring ,and fall, the sun fol- south sky, and sets in the west. How- lows a path betWeen the summer and ever, the sun actually Moves in a winter Paths. It rises due eadt, climbs slightly different' path every day.' In to about 55° above the south horizon winter, the sun rises slight south of at noon, and sets due west. Wal,ls due east, reaching the highest point - facing south, east, and west and only about 80 degrees above the roofs all receive moderate arbounts south horizon at wAn, and sets to the of sunshine. south of due west.. A south-facing In the temperate climate we ewer- wall receives the",most sunshine in ience in Arkansas, we need to both winter, while east, West, and north heat our houses in winter and cool ,walls all receive much less. them in summer. Orienting the solar In summer, the sun rises to the , greenhouse to the south makes it north ,of due east, climbs to nearly possible to take' advantage of the straight overhead (78°) at noon, and stin's paths as the seasons change. sets to the nOrth of ctue west. A verti- The greenhouse receiyes the greatest

0. 1 .amount,..àfiolar energy in winter, So even if the house is up to 45° off ,when heat is needed most, and (it is of due south, 75% of the sunshine easy to keep cool in summei with,the and heattng potential is still available. aid of shading devices or nearby trees. ActUally, a slightly southeast orienta Even if the, house does got haVe a tion is preferred 'by pany gardener's side that faces due south,,it may still because trxe greenhouse will heat up be worthwhile -to consider solar faster kr the morning,, the plants will greenhouse. The following 'table receive more of the favorable east ; .shows'the reduction in the amount of light, and overheating from the late

winter sun available to 'walls Which .1, afternoon sun in spring and suemer face slightly east or/West of south. is less likely.

Degrees East or °A Loss of West of South Available Sunshine 0 - 10° 0% / 10 -20° 5% 20 - 30° 10% 30 - 40° 20% 40 -.,50 ° 25 1)/0

D. GREENHOUSE HOUSE CONNECTION

More important than a true south air compared with the total possible direction is a comienient access to amount of water the air can hold. the greenhouse from the house. By Hbvidity is closely relafed to temper- building the greenhouse over exist- atuftthe colder the air, the less ing windows or a door, venting the water it can contain. Since a high warm air to the house will be made relative humidity (75% or higher) simple. If no doors are present, it is leads to pest and disease problems usually not difficult to make a door 'for plants, a solar greenhouse with its out of an existing window opening. cool nighttime temperatures ,should By haVing a door betWeen the be kept quite dry. house and greenhouse, you can avoid On winter days, the humidity in ,the having to enter the greenhouse from greenhouse is kept down by the con- the outside-in winter, which causes a stant air exchange with the house. great deal of the heat to .escape. This distribution of humidified air is Ideally, there should be two doors: welcomed, since the air in most hbmes one into the house for use in winter in winter is too dry because of fur- and one to the outside for ventilation naces, fireplaces, and other heating and access in summer. devices. Air circulition to the house is vital On winter nights, when there is no in control e relative humidity as air exchange to the house, the humid- well asihe temperature of the green- ity levels increase in the greenhouse, house. Relative humidity is defined especially if there are many plants. as he actual amount of water in the, Thishighhumidity can cause

10, condensatiOn, Which is the result of they tan provide access and a view "warm humid alr being cooled so the into the greenhodse and also serve as air can no longer hold,the moisture. vents when they are opened. Since the'glazing is the coldest sur- What type of connection you 'face in the, greenhouse, water will shobld make to the house often condense there first. This water pre- \depends on what type of room will be. sents three problems:water ,drop- 'adjacent to the greenhouse. For: lets on the glazing reduce the arnourft example, if the greenhouse is -to ad- of light that enters the greehhouse; join a kitchen or living room, the con- water may drip orito plants, hfitreas- nection would logically be' a door ing pest and disease probles; and- and/or windows. However, the, green- water may drip onto sills, p ornoting house may be connected to a bedroom rot. or garage where heat is not needed -To avoid serious con ensation during the day. In this case; a small problems, Open the doors', windows, thermostatswitched fan and insu- or vents to the house early in the lated ducts can be installed in the morning to rapidly circulate the attic to direct heated air to othei. humidified air into the house. As the rooms that areused in the daytime. greenhouse air heats up, it will be *The R value (thermal resistance) of able io absorb any condensed mois- the common wall between the house ture from the previous evening. and the grtenhouse it an iMportant The area of the open doors, win- factor in determining how warm the dows, or vents to the house should be4 greenhouse will remain at night. The at least 20% of the common wall area greenhouse acts As...additional insula- so the air will circulate adequately tiOn and preventsAifiltration through and no fan Will be needed. High vents the wall to which it is attached, trap- and low vents of equal areaiwill pro- ping heat that would otherwfse mote the ideal pattern of air circula- cape to the outs tde. If the common tion. Asithe solar heated air in the wall is not insulated, or has a large greenhouse is warmed, it rises into glass area, there will be considerable the house through the high vents. At heat flow from the house into the the same time, cooler air from the greenhouse On cold nights even with house, is drawn into Me greenhouse the doors and wihdows closed. How- 'through the lower vents. This natural ever, this heat flow from the house is thermqcirculition will perform con,' much less than would ocdur if there tinuously on any relatively sunny daY. were no greenhouse. So the green, Of course, mbst 'houses do not house serves an important function have ideally located high and ION as a "thermal buffer zone" between openings, and it would be impractical the house and the outdoors by reduc- to build them: Strategically located ing heat loss from the house at night ,doors and/or windows are, usually a in addition to cohtributing a large better solution than vents because- amount of heat during the day. ,/

or.

In this view of a solar greenhouse under construction, theforming for the concrete grade beam has just been completed and is ready for the pouring of theconcrete. The two large windows will provide good heat transfer to and from the building, and the concreteblock wall will help serve as heat storage. Note that the gas meter had to be relocatedoutside of the greenhouse.

111"101144. :IMMO

...001.,

The completed greenhouse shows how the rafters of theexisting building have been extended to form the roof of the greenhouse. This arrangement eliminates theneed for an interior beam or column. Although there are no vents in the kneewall, summer temperatures inside the greenhouse remain cool by using side wall vents (includIng a screendoor), roof ventilators, and shade from nearby trep.,(Village Preschool, Fayetteville)

12 . GLAZING

Glazing is glass, fiberglass, plastic, light comes in from all directions, or other'material which' apows light to just as if the plants were outside. But pass through. A larger glazing area re- in solar greenhouses, light enters sults in more energy collected and mainly from the south. To prevent the more heating of the greenhouse and plants from growing -towacd the adjoining house. south, the light must be reflected off Our studies have fOund that, for the side walls and house wall to simu- bestheatingperforniance,the late outdoor light conditions as glazing Should cover, only the south closely as possible. Such a balance face of the greenhouse and not the of light is difficult to achieve with a eaat or west walls, because much vertical-glazed greenhouse unless more heat will be lost through those the glazing is used in the roof or side walls than they will gain from solar walls as Well as in the south wall. radiation. The narrow configuration Such extenSive use of glazing will of the space and the reflective interior cause the greenhouse to rose more walls ensure that the plants will re- heat at night and will require addition- ceive enough light to grow properly al shading and ventilation in summer without east or west glazing. t event overheating. In Arkansas, the glazing should be Phototropism can be avoided in tilted to an angle of about 60° from reenhouses with tilted glaz,ingsif the horizontal: This angle will maxi- care is taken to arrange the plantst mize heat and lig transmission in. properly within the greenhouSe. The winter when the sn rises to its mid- light will always be stronOer from the day angle of abut 30° above the south, but a tilted glazing allows south horizon. Tus, nearly all the much light to also enter from above available direct ra lation, which is the and penetrate all the way to the form of solar radiation we r'ecehib on., house wall, where it can be reflected clear days, can pass straight through back to the plants. the glazing. Tilted glazing also col- In Arkansas, solar greenhouses lects a large amount of diffuse radia- will perform much better if two layers tion, which is the solar energy avail- of glazing are, used (double glazing). able on cloudy days. Diffuse radiation This was demOnstrated in an experi- represents about 25% of the average ment performedatthe Siloam total solar heat received in winter,in Springs Child Development Center ', Arkansas, greenhouse. After several weeks of Although vertical glazing is gener- continuous monitoring of in oor and ally easy to construct and shade in outdoor temperatures witdouble the summer, it must be designed with glazing, the inner layer of glazin was caution in solar greenhouses. In removed, and the monitoring ctin- some of the vertical-glazed green- ued with only a single layer of gling. houses that were studied, the plants A very consistent pattern emerged suffered from a problem called photo- showing night time temperatures in tropism;lhat is, they tended to grow the greenhouse to ,average 10° F at an angle towards the incoming 'warmer with double glazing than with light instead of straighi up. single glazing. On very cold nights, The reason plants grow so well in when the outside temperature drops conventional greenhouses is that below 15° F, this difference could to.

15.;-

Note how the bottom edge of the tilted glazing hangs overthe sill, allowing rainwater to drip directly into the gutterand eliminating the possibility of leakage. The knee wallwindows open_ outward to provide ventilation in summer.(Pulaski County Council On Aging, Little Rock. Photo.by Cathy Milmore)

14 determine whether or not the plants Fiberglas's is a common name for will freeze. Although the extra layer of fiberglass-reinforced polyester (FRP) glazing will reduce solar gain by glazing, which has been used for about 10%, it will reduce heat loss at many years as a patio and carport night by nearly 50%. covering. In recent years, several Tempered glass panels are by far manufacturers have formulated the the most preferred type of glazing for fiberolass with chemicals to resist solar greenhouses. Unlike fiberglass, yellolving and deterioration from the they are locally available anywhere ih ultraviolet rays of the sun. However, Arkansas and will never deteriorate. ,even these treated glazings need to Glass greenhoutes afford a 'clear be recoated every fewyears with a view to the outside, which is an im- special weathering agent to restore" portant consideration that is often the original finish and resist decay. overlooked, and will add more value Fiberglass is popular as a glazing to the adjoining home or building for solar greenhouses and collectors than the cost of the greenhouse. because it is light-weight, impactre- Most local glass companies stock sistant, and easy to cut and install. "replacement panels," which are Although it is cloudy enough to pre- tempered glass sheets used to make vent a view to the outside, fiberglass sliding glass doors, usually 3/16" thick will admit nearly as mucksolar radia- and in standard sizes of 28" x 76", 34" tion as glass. The cloudiness might. x 76" or 46" x 76", costing between be seen as an advantage in urban $20 to $30 per panel. Their superior areas where privacy is a concern. strength makes them ideal for tilted Fiberglass is usually available in 4- surfaces that must withstand severe foot rolls or 26-inch wide corrugated thermal stresses, wind and snow panels in various lengths and thick- loada, and impact from, hail and other nesses.ThebiggestcOmplaint objects. Often, panels with slight im- against the roll type is its appear- perfections (seconds) can be bought ance:it does not lie flat, resulting in at a very low price from Wholesala a wavy pattern. Corrugated panels are glass distributors and salvage stores. much mor?rigid and give the feeling Non-tempered window glass is of a more permanent structure. also locally available in single or Special redwood strips must be used double strength. Window glass can along the supports of the paneli for a be cut to custom sizes and has a very tight seal to prevent air infiltration. high solar transmittance of 0.91, but Also, the enlarged surface area of the is easily broken and should be used panels due to the corrugations will only in low-stress applications such slightly increase the heat loss at as vertical glazing. night. Sources of glass that are often Many solar greenhouse designs of overlooked are auctions, yard sales, the late 1970's used ,flberglass be- landfills, and demolition projects. cause its cost was so Much lesslhan Scrounging for old windows and glass. However, the cost of flberglass storm doors can save you hundreds has risen dramatically in the last of dollars arid produce a unique and, .three years, and its price now is very attractiVe greenhouse. Take the time near that of glass. Since glass is to investigate these sources in your available locally, affords a view to the area before buying any new glazlng. outside, and ispermanent, most solar Remember, used glass works just as greenhouses are now using glass well as new glass;' it just cosis a lot rather than fiberglass. less. Rigid plastic glazings are attrac

U 15 to tive, easy to handle and fabricate,and high cost and poor resistance have high impact and fractureresis- scratching. Like fiberglass products, products plastics .are petroleum-derived, so tance. Most of the plastic with can be categorized aseither acrylics their cost will continue to rise or polycarbonates.Acrylics, such as the cost of oil. Plexiglass, Lucite and Exolite, are Doubled-glazed glass, fiberglass, knowri for their high solar transmit- or plastic panels thathave been fac- tance and good resistance toultra- tory sealed to preventcondensation violet light and weathering.Polycar- are usually too costlyfor most green- bonates such as Lexan also have a houses. So double glazings areoften very high impact strengthbut will yel- assembled on the job, with an outer low in sunlight sooner than acrylics. layer of glass or fiberglass to with- The major disadvantages ofplas- stand the weather and an innerlayer tics as greenhouse glazines aretheir of polyethylene or vinyl film.

16 The lowest-cost inner .glazing is solar room again. polyethylene film.Itis commonly Another type of inner glazing is Used in the construction industry as a clear, flexible plastic or vinil film. vapor barrier, so it is available at most These films are usually sold "as storm building supply stores. Polyethylene window, glazing and are easily cut to comes in varying widths up tO 12 feet any size. When stretched over wood and can be stapled to the bottom of or aluminum or sáreen molding ,glazing rafters in one continuotis frames, they can be removed in sheet. Useful life is limited to one or summer and reused in winter for sev- two ,years; however, considering the eral years. Sy using the inner glazing low cost of the material, replacing it just in winter, when it is needed, it every year is not a problem. williast much longer than when it is Some very successful greenhouse left on year-round. These films are designs use polyethylene for both moir.e expensive than polyethelene the inner and outer layers of glazing. but are also much stronger, so they In, summer, the film is entirely re- can behandled from year to year moved to transform the space into without damage and, like glass, they outdoor garden or porch. In fall, new offer a clear view to the o,utside. plastic is easily installed to create a

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Bill Brown of the Office of Human Concern designed this vertical glazed 'solar greenhouse for the senior center In Berryville. Half of the roof Is glazed with fiberglass to permit light to enter from above and perrnit a light balance'within ihe greenhouse. A row of vents along the bottom of the south glazing and side wall vents provideventilation. There are four levels of plant shelves, each one supported by the vertical glaiing columns. The senior center prpfitably sells plants and vegetables to residents of the community. (Photo by Bill Brown). /

, 22 .17 ,REAT STORAGE

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Barrels filled with water support plant beds (under construction) and collect solar heat by day,, then release the heat at night.Since no shade cloth is used, the fan Is necessaryto ventilate the greenhouse in summer. (Strandguldt Greenhousp, Berryville)

18 The sunlight that. enters the solar earth. Heat absorption needs to occur greenhObse falls either on the plants, in direct sunlight to be,effebtive, so onto light-colored surfaces that re- the heat storage materials should be flect light back to the plants, or onto located where they will not be shaded heat storage materialt. These are by the plants. heavy, dark-colo(ed materials that The amount of heat storage needed have a high thermal mass, which to keep greenhouse temperatures means they act like heat "§ponges" stable will depend on how closely the to absorb solar heat during the day greenhouse and adjoining house and slowly release this heat to the air interact and share heat.Ifseveral at night as the space cools down. The large vents, windows,, or a fan con- solar heat received by the green- nect the greenhouse and house, the house is therefore extended over a house will immediately receive the much longer time than When the sun excess solar heat arid prevent the is actually shining. greenhouse from overheating. If the Without heat storage materials, the openings' are few or small between air temperature inside the green., the house and the greenhouse, more house would get very hot on sunny heat storage may be needed.

.. days (over 140° F) and cobl' off rapidly The recommendedminimum at night. These extremes in tempera- amounts df thermal storage are: ture from day to night are undesirable For every square foot of glazing: and uncomfortable for both people 4 gallons of enclosed water or and plants. Temperatures above 100° F 1 cubic foot of gravel or earth or can severely limit the growth ofplahts .75 cubic foot of rocks, bricks, or and kill many of them. M ssive heat blocks storage materials tend to.abilize the When you are thinking about9how

,temperature, improving ttte comfort and where the heat storage will be .of the greenhouse forfaeople and pro- placed in the greenhouse, you must moting produCtive plant growth. also consider the arrangement of the A good way to uVerstand the na- planting beds. The planting beds and ture of heat storage materials is tO the heat storage will be competing' think of being in a cave, where the for' light, so the design of both ele- temperature never changes regard- ments needs to..be integrated for ef- less of-whether it is sumrher or winter. ficient use of the space: A combina- The temperature doesn't fluctuate be- tion of water containers and masonry cause the earth, with its enormous and earth planting beds are often the heat storage capacity, can 'absorb a most practical solution. lithe house large "amount of heat in summer and, wallisbrick or exposed concrete gradually lose heat in winter withoiit block, it can serve a large portion of affecting the air temperature in the the heat storage requirements. 'cave. To a lesser degree, the heat Dark-painted 55-gallon barrels of storage materials in the greenhouse water are the most cOmmon form of act the same way:slciwly absorbing thermal storage becauSe they are in- and releasing energy to maintain expensive, locally available, and even air temperqtures without any easily arranged to form supports for ...... , mechanical c9ntrols. . - planting beds. Flat black is the most VariOus kinds of heat storage ma- efficient color to absorb solar energy, terials have been used successfully but a dark blue, green, or reti will do in solar greenhouses, including bar- nearly as well. In a typical 8 'x 16 ' rels or other containers full of water, greenhouse, 7 to 12 barrels should be rocks, bricks, copprete blocks, and d used, with as many placed in direa 1 At

19 sunlight as possible. They must be can be compactly stacked against well supported and level, especially one another, with all sides touching. if they support illanting beds, or wilt This arrangement saves space, elirni- be stacked One on top of the other. If natesqbe, need for racks, and will `the barrels are stacked, separatethe\ absorb- ehtiransfer solar heat belter upper barrels from the lower barrels', than barrels. with 2 x,41's or other bo4rds solhee''' arA excellent storage will have continuous 4upport.Also, it mectif*AlOst people use.,it without is a good idea to place a 1or 21 layer realiZtng 4nat it tacting as thermal of bead board between the barrels storageMet soil' n particular has the and the floor so the water will lose its capacitkftgh&d a lot of heat and to heat to the air rather than to the floor. relealse.itvery slowly. Other containers that can be ysed IfderPkoloredocks, bricks, or are recycled glass or\plastic jugs in concrefe' bloCk re used for thermal- which water has been dyed prack. They should be incorporated They must be placed on' ragks to:pre- 'aspd f Ihe planting beds, floor- vent them from breaking (Under their ing, or Wall -Veneer. In this way, they own weight. will servefOh istheat storage and as . Rectangular-shaped, 5-gallon hney structueal elements in trw green- cans or gasoline cans are ideal foe house. I use as thermal storage because they

G.SiNTERTIME TEMPERATURE CONTROL

Solar greenhouses built in Alk lemirperatures and increase the heat- kansas to the specifications in this ing fuel savings of the home. Glazing repOrt 'will. grovx, cool-tolerant food is the largest heat loss problem of plants du winter withoul'atiatfliery any greenhouse-.--tvr well-sealed heating. For p ants requiring warmer double glazing Will lose heat at night, minimum te eratures, such as about 12 times faster than On insu- tomatoes or fruits, you may have to late'd wall. Movable InsulatiOn corn- slig.htly open the door or windowS pletelY covere the glazing at night and into the greenhouse on.very cold (00 - is removed during the day to permit 10° F) winter nights to allow more solar heat gain. heat to flOw 'from the house into th vering large gltazing areas' with greenhouse.' mova'BrPnijjatiorr presents several There arg two alteThative.sock,this design proble .A successful systern auxiliary heating method. One IS tq must: place a wood, gas, or electric heatint device in the greenhouse. If you have to be gone frA a few days; an .e.lectri- Be easy tooperate. cal heating device on a thermbstat would be the most efficient because Not interfere with the prints. it would only come on if and when the greenhouse temperafre dropped to Be conveniently retrabted or, the required minimum. stored during the day. The other alternative is to use Inov- Have a tight fit when the insu- able insulation over the 9lazing at lation is covering the glazing at night to maintain warmer nighttime night.

20 .Types of movable insulationin- occurs at the seams of rigid panels. clude rigid panels; folding shu4ters, The curtain is oually drawn to the and thermal curtains. These are norm- tokof the glazing`by a cord arid pulley . ally used on the insideof the glazing, harOware system like a Roman shade. although some greenhouses use...ex- There stWuld, be space allotted above terior shutters. Exterior shutters are the glazing so that the thermal cur- usóally knsulated panels that are tain will not block the light when it is hinged to the greenhouse along the rolled up.

, bottorroof the glazing. They are folded It should be remembered that,.with down during the day to reflect addi- the t xception of the bead board pan-. tional solar energy into the gree'n- els, movable insulation systemsill house and are closed by hand or bya r add considerably to ,the cost, com- wench and pulley system to serve as plexity, and maintenance of the >,insulatign at night. greenhouse. They are worthwhile The simplest amd most practical only if warm (50° to 60° F) nighttime movabTe insulation is rigid styrene, temperatures are desired. also called bead board. Normally pur- Of all the methods to pontrol winter- chased _as, 4 ' x 8 ' sheets 6-at are lii time temperatures at night, the most or 2" thick, bead,board is a very. light- preferred is to simply leave the door weight Mate ial that can be eay cut or windows open, allowing heat from vOth a utilitknife to fit betwe n the the qouse to keep the greenhouse glazing raft rs for a tight seal. A warm. This method will never have to ,simple wooden latcp can be" used to be used if you are growing only cool- locrk the panels in plaop against the tolerant plants and have agequate glazing. A convenient daytime stor- amounts of thermal storage and ins.u- age area foe the panels should be IMion. Eyen if you grow plants that re- planhed somewfiere : inthe', greep- quire' higher minimum temperatures, house so they . Will not Shade the you will probably have to leave the plants or thermal storage. door or windows open only a few 'Thermal curtains can be made with , nights-a year, when the outside night- a sewing, machine by quilting a 1" time temperature drops below 10° F. layer of polyester insulation and a The arnount of heat the house gives polyethylene vapor barrier between the greenhouse on thete few nights two layers of fabric. Curtains should is far less than the, total heat the cover the entire glazing in one piece, greenhouse supplies to the house thus eliminating the heat loss that throughout the winter. - v . SUMMERTIME TEMPERATURE CONTROL

There are two main factoth that dp- - 10' to15 of The site, consider plant- termine solar greenhouse tempera- ing hvo orAhree fast-growing, early- tures in surnmer:shading and venti- blooming trees. Your loc4 Soil Con; lation. A combination of the two is servation off icescan belp 'you make usually necessary to prevents over- the right choice for yotParea. heating during the warm, humid sum- Alternatives to shade trees 'are a mers of Arkansas. shading lattice or a shade clotti at- The sun is at its highest position in tached to the outside of the glazing. the sky during' summer,- striking the A shading lattice is a lightweight wire glazing at a steep angle and causing or wooden mesh, built in sections, much of the light to be reflected off that is removed at Ahe end of summer. the glazing. However, since the out- Care must be taken not to totally side temperature is warm, it doesn't block all the sunlight, or the plants take Much soler radiatiom to raise the may not grow well. The lattice can greenhouse temperature. The best also be used as a support for vines or shading method is to have deciduous other plants to further shade the trees j(those that lose their leaves in glazing.. fall) Close to the greenhouse. They t A shade cloth is a popular shading will block most of the solar energy in device used in conventional green- summer, yet will allow the sunlight to houses. Made of an inexpensive but reach the greenhouSe in winter.If highly durable plastic called polypro- such trees do not already exist within pylene, shade cloths ate an ex'cellent

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A screen door serves as a vent as well as a door in summer. Screens over all the vents are necessary to keep out insects. Note the two small lower vents on each side of the screen door. (Village PresChool, Fayetteville) solution toihadingproblems. Shade In May of 1981, shade cloths rated Cloths are custom ordered with grom- at 50% shading capability were at- mets sewn into the edges to fit your tached to three different Arkansas greenhouse. The grommet holes solar greenhouses being monitored stretched over small hooks at ed, for temperature control. The shade to the greenhouse for a neat ear- 'cloths were installed onto the green- ante and easy removal in the houses in the afternoon on clear days

24 29 . so that the immediate effect on green- Thermal .chimneys can be made houseb temperature could be ob- from common attic ventilators (Wind served. With the outside temperatures turbines) which can be purchased at averaging 85° F, the inside tempera- most building supply stdres. Sec- tures dropped an average of 20° F tions of galyanized metal duct pipe within 30 minutes after the shade cloth are' painted a dark color and con- was installed. The owners of the nected to the base of the ventilator to greenhouses have reported no ad- extend its length as much as pos,,, verse effects on the plants as a result sible. When the sun strikes the chim- of the shading. ney, ,,the air inside warms and rises Figure H-1 shows a comparison be- upward, pulling air frorn the green- . tween shading methods. 'Whatever house and creating a draft. The long- technique is used, be sure to place er, the-chimney, the hotteethe air will the shading device on the oWside of get and the more air will be drawn the glazing. An interior shading de- through the greenhouse. If the wind vice will block the sunlight only after is blowing, there will also be a draft it has passed through the glazing, created by the whirling turbine on top causing heat to 'build up between the of the chimney. Performance of the device-4nd the glazing, thus reducing dhimney can be drastically improved the effectiveness of the device in by wrapping it with a layer of flexible controlling greenhouse temperatures. fiberglass glazing so the air inside , In addition to shading the glazing, will get much hotter. The chimney is ventilation of the greenhouse is vital eesily sealed during winter from infor reducing temperature and humid- side- the greenhouse by an insulated ity and in9reasing the level of carbon shutter. dioxide, which the plants need to en- If for some reason you cannot in- sure healthy growth. Since most of clude enough vents or shading for the the wind in summer in Arkansas greenhouse, a fan may be necessary. comes from the south, it is a good The proper fan size will depend on idea to build' a continuous row of how much shading and ventilation openable windows into the south exists but a rule of thumb is a CFM knee wall of the greenhouse. Addi- (cubic feet per minute) rating equal to tional vente high on the-east and west at least two times the floor area. So a walls or roof are also needed to pro- greenhouse with a floor area of 150 mote a thorough air exhaust. Doors or square feet would need a 300 CFM windows that can be screened and fan. opened can saVe as vents. The ,total A propeller-type window fan should vent area should be 115 to 113 of the be placed in a screened opening high floor area, depending on theishading on the west Wall. This arrangement available, to avoid using any mechan. will pull cooler air frorri the east side ical ventilation. to the ilptter west side. A thermostat Roof vents have been more diffi- on the fan is recommended to reduce cult to build because they have to be power consumption and guarantee comriletely water tight when closed. that the greenhouse will not overheat On the other hand, the roof is the best if you are gone for a few days. place to put exhaust vents for good In winter, the fan can be rearranged . air circulation. A newly developed to blow solar heated air through a .roof vent that has been proven to be window into the house if necessary. effective in Arkansas and is relatively Be sure to seal all the summertime easy to build is the thermal chimney. vent openings air-tight in winter.

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Thermal chimneys,lhown on theleftarePassiVe, self-regulating ventilation devices that can help keep the greenhouse cool during summer. The chimheys.are painted dark green or black to Increase the alr temperature within the shafts and thus In- crease the air movement through the greenhouse. (0.H.C. Child Development Center, Siloam Springs)

26 GREENHOUSE GARDENING

The skills of horticulture cannot be tritional benefits from a solar green- fully conveyed in this or any other house, food plants that have a high single publication. Learning to grow nutritional content in a small'groWing plants can be a lifetime's work of area should be grown. Of course, study, experimentation, and applica- starting seedlings for transplanting tion. If you already have some garden- to the garden or growing house ing .expdrience, growing plants in the plants for sale are also excellent uses greenhouse will be easy once you of the solar greenhouse. learn the light and temperature varia- In general, leafy salad-type crops, tions during different times of the such as lettuce, spinach, kale, chard; year. If you have no gardening exper- endive, chinese cabbage, celtuce, ience,itis not difficult to acquire kohlrabi, and collards, do best in gardeningskills by learning from solar greenhouses. Tomatoes, cu- those who have gardens. Whether or cumbers, peas (edible pod types), not you have a knowledge of horticul- onions, leeks, chives, and eauliflower ture, it is advisable to read books on can, be grown if attention is paid to the particular growing techniques the required growing conditions of used in solar greenhouses. (See Ap- the varieties selected. There are sev- pendix B.) eral characteristics of the crops to To get the most economic and nu-" consider for a solar greenhouse: light

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Photo by Mary Jo Rose 32 27 requirements, cold tolerance, size, ir winter are listed first and marked daylight period required to flower and' (W); other, varieties for ,spring, sum- set, fryit, time required from 'planting mer, and fall are also listed.Those to harvest, pollination and disease re- varieties that should _be grown in sistance. Special greenhouse varieties spring and summer only are marked have been bred to yield fruit in cooler (S). environments, or with shorter days In the fall, some of these vegetables than the standard varieties. Some can be transplantedirito.the green- varieties are more disease resistant house from the garden, especially to- than the parent plants. matoes, peppers, onions, and broccoli. The following table,- from the Prepare for transplantirig at least two Organic Gardening Research "Center weeks prior to the actual move by cut- inManatawny, Pi.,listsrecom- ting the roots with a shovel midway mended food crops and their horticul- between adjacent plants. This will en- tural requirements. Our studies have courage more root growth close to shown that these kecommendations the plant, thus helping it survive the are valid for solar greenhou§esin Ar- move. kansas. Varieties that will grow best

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28 FOOD PLANTS FOR PASSIVE SOLAR GREENHOUSES

Aarit Verieties Soil Temp:* Location Special Instructions

Tomato Cherry types, especially "Sweet 100" (W), 50 Full sun on trellis' Requires 20" of root depth, if in containers must Big Boy (S), Better Boy (S), Beefsteak (5), up back wall be 12" or larger in diamater, trim suckers

'Cucumbers LeReine (5), European (S), Burples/ types 60. Full sun on trellis Require hand pollination (5), Toska, Gourmet (S) up back wall

Peas Mammothmeiting (W), Sugar Snaps (W), 40 Shady, cool areas Grow on teepee of four poles in back corners of (Edible pod types) Mighty Midget (W), Dwark White Sugar (W) greenhouse-or on trellis up side walls.

. Onions: leeks, Any (W) 35 Cool, medium light Garlic helps control insects, bulb growth is Scant, chives, shallots, toward sides of tor all,- tops good in salads, space further apart- - garlic midsection of than usual, greenhouse ) / Cauliflower. Snowball (W), Super Snowball (W), Abuntia (W), 40 Cool, medium light Reuire much space tor the crop harVested; do well- , Snowcrown (W), Snowking (W) jn pots, good tor early iransplanting to garden.

Cabbage Mart Morden (W), Jersey Wakefield 40, Only one head harvested per plant

Chinese Cabbage Burpee Hybrid (W), MIchihtl (W) 40 Cool, medium light Excellent for tall-winter greenhouse, continuous harvest,

Collards Vater (W), Georgia (W) 40 Same as above Same as above.

Kale Dwarf Blue Comet (W), Dwarf Blue Scotch (W) 40. Same as above Same as above.

Kohlrabi Early White Vienna (W) 40 Same as-above Same as above

Broccoli Southern Comet (W), Calabrese (W), White 40 Same as above Same as above Sprouting (W),,Green Comet (W), Premium Crop Fl

Pepper& Almost all red, green of bell varities work' 60 Warm, full light Hand po nate, do well in pots careful not to ovenhater

Endive Salad King (W), Broadleaved Batavin (W) 35 ,Cool, medium ligbt Good winter producers, may be grown under tomatoes or peas in back ol greenhouse

Spinach Monnopa (W), Bloomsdale (W), Perpetual, 35 Cool, Medium light Same as above, continuous harvest New Zeland

Swiss Chard Vintage Green (W), Fordhook Giant (W), 35 Cool, medium light Tastes better alter cool weather Good producer, Lucullus (W), Ruby (W) continuous harvest

Radishes White Chinese (W), China Rose (W), Summer 40 Anywhere ;.Double numbor of days to mature crop Cross (W), Hall Long (S), Yellow Gold (5), Icicle (S), Champion (S)

Beans Kentucky Wonder (pole) (5), Blue Lake (pole) (s), 60 Medium, light Not good for midwinier crop, don't overeater: witi Tenderpod (bush) (5), Royalty (bush) (5) easily rot. Watch for yellow bean beatles

Lettuce Buttercrunch (W), Grand Rapids (W), Ark King 35 Cool, medium light Avoid head lettuce, watch for aphids, continuous

(W), Tom Thumb (W). Green Ice (W), Salad harvest. . Bowl (W), Great Lakes (W), Celtuce, Oakleaf, Bibb

Beets Ruby Queen (W), Detroit Dark Red (W), Burpee 40 Medium light, cool Young foliage excellent as a green, plant farther Golden (W), Snow White (W), Asgrow Wonder (W) .apart than usual, require loose light soil

Carrots Tiny Sweet (W), Short-n-Sweet (W), Little 40 High light, warm Plant heavily then thin progressively, require Finger (W), Golden Nugget (W) loose, light soil and sand

'Minimum soil temperature for germination in °F Many crop varieties benefit from moving them to the greenhouse. starting in pots or fiats, then trans- Recent research at the Organic planting to the garden inspring. Gardening Research Center has These include tomatoes, peppers, shown considerable success with eggplant, melons, broccoli, and other crops developed in China for growth coie crops such as cabbages. through that country's damp, chilly, Some of the-warm weather crops overcast winters. These various will not germinate in the greenhouse greens can be eaten fresh in qalads or but will grow there once started. You cooked in soups and casserbies and can get them going by keeping them are very prolificin _passive solar in the house until they sproud, then greenhouses.

CHINESE VEGETABLES-

Siew Choy (Brassica pekinensis var cylindrica):leaves are wrinkled with celery- like midrib. About 8 inches tall. Pick outer leaves. Seppaku taina (unk):grows bunched likecelery,''having broad, soft leaves on white stalks. Can be planted close together.Good eating even after hard freeze. Bok choi (Br. chinsensis var. Chinensis):chinese cabbage. Will survive temperatures in_the mid 20's. Pick regularly to preventheat formation.. Choy sum (Br. paracninensis, Bailey):flowering white cabbage, looks similar to broccoli. Eat flower stalks. Eat entire plant assalad or stir fry. Dai gai choi (Br..juncea var. rugosa):loose, umight head with curly leaveshaving a sweet, peppery flavor. Gal choi (Br. juncee var. (oliose):fast growing (space at 6 inch intervals), with mild mustard flavOr: More leafy than Dai gaichoi. Komatsuna (Br. pervidis Bailey):very cold tolerant, compact,resembles young chicory. Slow growing. eh . Kyo mizuna (Br. juncea var. muttisecta):resembles fine endive. Fast growing. Mild and pleasing flavor for salads. Shungi ku (Chrysanthemum coronatium):young shoots exceltnt in salads. Continues to grow when clipped back.

30 Thegreenhouse environment house environment by plantinig differ- changes with the seasons. In the ont crops in each season. Remember winter it is cool but warmer than out- , that it takes 11/2 to 3 months between side; in the summer It is warm but can the planting and harvesting of most be cooler and more shaded than out- crops, so crops planted in the late side. As in the outside garden, some winter will be harvested in the Spring. , crops do better in cool weather, The following, table gives some others in warm weather. You can take recommended &bps to plant in each advantage of the changing green- season.

PLANTS

Fall Cool weather crops for winter Oct. lettuce,radishes, onions, herbs, broccoli, cauliflower, peas, spinach, beets, carrots Nov. chives-, cabbage, swiss chard, oniOns, kohlrabi Dec. start seeds inside to germinate crops as in Oct. and Nov. Winter Cool weather crops; early/spring crops and garden transplants; late Jan. collards, spinach, cauliflower, broccoli, onions, swiss chard, cabbage, beets, flowers , Feb. beans, lettuce, cabbage, herbs & peas in greenhouse, tomatoes, peppers, cucumbers, and others for garden March tomatoes, cucumbers, peppers, eggplant, peas, beans, cabbage, broccoli, cauliflower, spinach in greenhouse and for garden Spring Warm weather crops for summerlindtransplants for garden April melons, squash, corn (transplant) and others as in March May Same as in April June tomatoes, cucumbers, peppers, eggplant, squash, melons Summer Warm weather crops; early/cool weather crops for fall; late July. . peas, carrots, onions, peppers, tomatoes, cucumbers, squash Aug. cabbage, broccoli, spinch, cauliflower, beets, peas, onionsrherbs, radishes Sept. lettUce, chinese'cabbage, swiss chaed, kale, beets, broccoli, spinach

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31 .*

An existing concrete slab and abricX wall offer Ideal conditions for heat storage .In a solar greenhouse. A generous growing area IsprOvided by thedouble-level plant bed-along the knee-wall and along the building wall on tetp of the barrels:The upper level bed along the' knee 'wall should be built several inchea below the sill so the plants willhot touch the glazing,- and the lower bed should be raised slightly off of the concrete floor to allowfor drainage.

Because of the demands. your equal mixture of compost, sand, and crops will make on it, your green- whatever garden soil is available. The house soil needs to be very rich. It is 'attractiveness of this system Iles in - certainly possible, to buy premixed recycling, through the compost, of (potting) soils, but the quantities re- kitchen and garden waste. quired make this approach exceed- Soils can be contained in pots, ingly expensive. Experience has raised beds, or ground-level beds. shown that the .1ypes .of chemical The use of numerous small pots on fertilizers used in .agriculture tend to tables or benches isnot recom- give poorJesults in greenhouses. mended. These tend to dry out very Thus two asic approaches remain. easily and the roots can experience (1).A su able soil can be obtained wide temperature shifts. The best ap- by mixing e ual parts of good topsoil, proach seems to be,a combination,of sand, and a soil lightener such as per- beds toward the front of the green- Ilte or peat moss. Additional nutrients house and pots and/or flats in the rear can be added In the form of compost, or on or over the heat storage con- pr rqtted manure. tainers. (2) The best soil is perhaps an.

32 CONSTRUCTION. METHODS

There are several factors to consid- where the greenhouse is to he at- er when designing a solar green- tachegi. Itis very helpful to draw a house, including what type of plants plan and elevation of, the proposed will be grown and how the green= greenhouse on graph paper. Note any house will be adapted to the house. obstacles such as wires, electric or for basy access and heat distribution. gas Meters, or trees. Look at the line. There is no one way to build e solar of the ground against the h9use and greenhouse; -rather,, it should reflect measure its slope. If youlive In a the needs and resources. of the suburb or city, make sure your)ot)ine -owner. is pot withirifivefeetof the The following 9#:instruction Methods greenhouse. Check with your local are given for a greenhouse design government to see if you will need a that has performed 'well in Arkansas. building permit. The details may need to be modified Clear the site of any unwanted to stilt the particular conditions of shrubs, trees, or plants before you each' site. start working. To give you a good idea of the layout, place stakes in the 1. PREPARING THE SItE ground where the walls will be located. Fig. J-1' indicates the equal Before starting to dig the founda- lines of measuremerilko ensure that tion, measure' the wall of the house the foundation will be square.

38 33 2. FOUNDATIONS " , The toundetion should evenly sup- The bottom of the trench may slope port the weight of thegreenhouse with the ground, but-the top of the arid should be square andle,t3Kgro grade beam should be 6" above the that the walls will fit together ankd at- highest corner of the ground and re- tach to the house without gaps.Since main level around the entire perim- the greenhouse itself is a lightweight. eter. FOr -example,ifthe ground structur, a conventional ,foundatIon, *slopes down lowards the west a total such as those,for houses, Is notneed- of 24", then the topof the grade beam ed: Whatever foundationisused, will .be 6° above the ground onthe make sure it is well Insulatedfrom east side and le" above thegroUnd the ground:next to heat loss through on thewest side. the glazing, the foundation offersthe If the ground is level, yau can use 2 greatest avenue for heat loss. x 6 boards, to formthe exposed sides The sturdiest and most permanent of the beam. If the ground slopes, use foundetion for sites that sldpe less 1/2" plywood Wilth 2 x 4 supports every than 24" is a poured c te grade 16" to form' tl4e necessaryheight to beam. (Fig. J-2 and Fi .J 3 grade keep the top of the grade seam level. beam is' simply a c.ntinuo con- Line the side and b mi of the crete footing that extendsabb the trench with 2" polystyreneawn insu- 'ground. First, dig a trench 10" ide lation (bead board),, then place two and 12" deep eroun0 the, perimeter. No. 4 reinforcing bars. continuously

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through the trench as indicated. If the to the fotindatiOn. , 'foundationis small, you may want to qince both sunlight and ground use ready-mix concrete or make con- moisture will .deteriorate the "bead crete from a mixture of one apart ce- board insulation, Vis important to ment, two, parts- sand, three parts protect it with plaster or some other gravel and enough water to mix. Be' waterproof coating. An alternative in-' sure tp place 1/2" x 8" ancqor'bolts sulation is Styrofoam (blue), which is , every4' into the top of the grbde more expensive but much more resis-

,beam, with the threaded part extend- tant to moisture and acids in the soil. ing 3" above the top of, the beam. If the ground slopes more than 24", These are used to tie down the walli a grade beam may be impraptical be-

35 FIG. J-4 cause of the large amount of con- lation. Waterproof the wooden sides' crete and extensive 'forming neces- with .three layers of foundation coat- sary. For such steep slopes, a con- ing '(tar) and felt, then fill the cavities ventional concreteJooting and block between the posts with insulation wall foundation is more appropriate. (fiberglasS, cellulose, or styrend Details of this type& foundation can beads). e found in any caficientry or house Otk railroad ties are common saw- building book. mill products in' many parts of Arkan- A less costly alternative lo a con- sas and can be used to make perhaps crete foundation is one that uses the least costly foundation. The treated posts or railroad ties. These ground should be fairly tevel and, as types of foundations havebedn used . shown inFig.J-5,atleast three for greenhouses' inru'ral reas that courses of 8" x 8" oak ties should be are not restricted by buildi 9 codes, -used. Start by digging a 16" deep by Fig. J-4 shows a typict post foun 18" wideleveltriii ich around the ckation. Begin 0.diggina 12" deep perimeter. Place 4' 'bf pea gravel .in by 18" wide trench arou1ifd the perim- the trench and lay the first course of eter Set treated 4 x 4 p sts in holes ties after the bottoms have been ' deep and 4 ' apart in the bottom of mopped with tar. Using,a sledge ham-' the trench. Install the treated 4 x 4 mer, drive a 1/2" x 3' reinforcing rod baseplates 'between the posts, then or pipe through holes drilled in the nail treated boards 'dr plywood to ties every 4'. Each succewling layer both sides of the.posts to tie them to- of ties is spiked to the one below i.t,in . gether and. form a cavity for the insu- a similar manner. Coat the outsiOe ,

36 edge of the ties with three layers of the side walls or roof, these openings Jar and felt, then nail or glue on the 2" greatly reduce the arnount,of Shading bead board insulation. necessary tovrevent overheating. Fig. J-6 and Fig. J-7 illustrate typical 2. The knee wall rnakes possible greenhouse details using tilted ternp- a double=decked planting arrange- ered glass panels (34" x 76") and a ment:one bed at ground level and vertical'knee wall with openable win- one bed at the top of the knee wall. dows along its entire length. A knee Light reaches the lowdr bed through wall with windows serves two irnpor- the vertical._ windows while the upper tant functiqns: bed receivbs lightfrorn the tilted glass panels. This arrangernent en- 1. In surnrner, the knee wall win- ables the owner to grow about 40% dows are used as vents to allow, a rnore in the greenhouse than if just generous flow of air into the green:- one bed were used. house.. Along with srnaller vents on

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43. 38 1 3.CONSTRUCTION SEQUENCE

A. Construct the built-up beam E. Determine the cutting pattern that will support the glazing rafters for the glazing rafters by holding a 2 x and the roof. If the greenhouse is less 4 against the end of the beam and the than 16 ' long in an east and west di- sill. After cutting the patterns, nail or rection, this beam can be made by screw together two Of the pre-cut 2 x bolting together two 2 x 10's with a 4's to méke each glazing rafter 3" layer of 1/2plywood in between. lf wide and 31/2 " deep. Since these raft- the greenhouse is longer than 16 ', ers will be exposed, be careful not to then either a larger beam or an inter- damage them dyring preparation or ior column will be necessary. installation. Scrift the glazing rafters into the beam And the sill with 4" x B. Place the beam in its correct 1/4 " wood screws. Fig. J-8 shows the location by supporting it with two 4 x glazing details at the east and west 4 columns at each end. The ends of ends of the greenhouse. the beam should be plumb with the outside edge of the foundation. Brace F. Frame the side walls with 2 x the columns and beam with temporary 4's on 24" or 16" centers. The con- diagonal braces until the roof rafters nection or the,wall studs to the roof and walls are in place. Make sure the rafters is shown in Fig. J-9. Wall vents beam is level and is at the correct are screened openings with insulated heig`ht above the foundation. doors that swing inwards. The vent doors are made from a 2 x 2 frame C. Nail or screw 2 x 6 ledger plate with 1/4 " plywood nailed to both sides on the hoese wall. Hold a 2 x 6board and bead board insulation on the in- against the ends of the ledger and side. Be sure to weatherstripall beam and trace their outlines with a vents, doors, and windows so, they pencil, then cut all the roof rafters to are air-tight when closed.. this pattern. Nail the pre-cut 2 x 6 roof rafters from the ledger to the beam on G. Paint the- glazing rafters and 24" centers. There should be enough the sill with two cots of clear marine downward slope towards the south to varnish. When dry, apply a continu- allow rain to run off easily. Use joist ous bead of. clear silicone rubber on hangerslo connect the rafters to the the top edge of each rafter and ledger. beveled edge of the sill and then install the glass. Nail temporary wood ,D. Build the knee wall on the blocks below the sill to prevent the ground, then tilt it into place on the glass from sliding off the rafters foundation wall. Since the glazing before the silicone rubber dries. After rafters will be on 35" centers, the 4 x the rubber dries, remove the blocks 4 knee wall supports (mullions) and install the batten strips, which should be on 35" centers also: Knee can be either 1 x 4 cedar or galvanized wall windows can be made with 2 x 2 steel. Next, install the gutter with frames and double strenth glass..A downspouts areach end. The gutter brass piano hinge at the top of the is very important because it prevents windows allows them to swing out- water from saturating the knee Wall ward so as not to disturb the plants and lessening the chances for decay and to remain open while it is raining. and leakage. The gutter can also be Screened frames can be placed in the utilized to collect rain water for the openings in summer to keep out in- plants. sects and can be removed in winter so that adequate sunlight Can enter.

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H. Finish the outside of the roof side. with,1/2" CD plywood decking, 15 lb. felt, and asphalt shingles or"roll rbof- I. The framing for the beds may ing to match your existing house be treated with copper naphthenate roof. Nail 17 bead board to the out- to resist rotting; do not use creosote side walls, then tape or caulk all the or pentadhlorophenol (penta) to treat joints from the outside to prevent air lumber in a greenhouse, because leaks. Apply whatever siding material these substanbes are harmful _to you desire to the bead board sheath- plants. ing. The inside of the walls and roof- are finished with fiberglass insulation J. Place 4" to 6" of pea gravel on (31/2" in walls and 6" in roof), a 6 mil the floor and 55-gallon dark-painted polyethylene vapor barrier, and 1/2" barrels of water against the hoyse ,sheetrock (preferably the water- wall. (Stee section on "Heat Storage") proofed type). Paint the walls and More Ølanting beds and shelves can ceiling with two coats of white-exter- be placed above the barrels, making. ior latex or enamel. An alternative the total planting area at least equal interior finish is1/4 " matonite that to the floor area. has a plastic laminate surface on one

:kr '111

43 K.CASE STUDIES

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Owner,Ozark Food Co-Op - Location:Fayetteville Length: 40 Width:8' Area of F(oor...320 sq. ft. Tilted South Glazing:366 sq. ft. Type:340 x 76' tempered glass panels with an inner layer of 4 mIl polyethylene in winter Vertical South Glazing:132 sq. ft. Type:48' x 34' removable awning windows glazed with double strength glass and an inner layer of 4 mil polyethylene in winter East Vents:28'sq. ft. Type:.a 3' x 6'-8" door with screen door and an upper 2' x 4' wall vent West Vents:12 sq. ft. Type:upper wall vent Roof Vents:None Openings to Bullding:40 sq. ft. Type:5' x 8' doorway (a 200 CFM thermostatically controlled blower also delivers air to the building) Thermal Storage:Nine 55 gallon barrels of water.(4140 lbs) and a 1' thick brick wall (existing) Planting Arrangement:, Upper and lower shelves-along south knee waH (80 sq. ft.)for flats ant,:.1/ pots and 20 sq. ft. of ground level beds against the north wall Shading:None at present. Although the vents along the knee wall provide much ventilation, it is felt that some shadIng,will be necessary In summer CONSTRUCTION Floor:Earth Foundation:Poured concrete grade beam (6' x 18) with 2' bead board on the inside surface Side Walla:1/2' plaster on metal lath, 1/2' fiber board sheating, 2 x 4's on 24' center§ with 31/2' fiberglass, 4 mil polyethylene vapor barrier, I/2' sheetrock Glazing Rafters:No. 2 pine 2 x 4's on 36' centers; painted white Roof:asphalt shingles, 15 lb. felt, 1/2. CD plywood, 2 x 6's on 240 centers with 6' fiberglass batts, 4 mll polyethylene, 1/2" sheetrock COSTS Materials:$1400 (Labor Cost: $1266) Builder' Joe Henry

44 V.

4%.

Owner Northwest Arkansas Economic Development Daftly, Inc. Location:Harrison Senior Center, Harrison Length:12' Width:8' Area of Floor96 sq. ft. Tilted South GlazIfig:72 sq. ft. Type:34' x 76' tempered glass panels (single glazed) Angle:85° Vertical South Glazing:None Roof GlazJng:72 sq. ft. Type:34' x 76' tempered dlass panels (single glazed).. East Vents:2.5 sq. ft. Type:upper (12' x 20') and lower (8' x 12') wall ients West Vents: Same as east vents Roof Vents:None , Openings to Buildings:48 sq. ft. Type: Two 4'1x 6:awning windows Thermal Storage:Seven 55 gallon barrels of water . Planting Arrangement:removable flats on top of barrel planting is done entirely in pits and seedling trays Shading: Nonethe bullding Isflot usedin summer

CONSTRUCTION, Floor4' pea gravel Foundation:6' x 18' poured concrete grade beam, no insulation' Side Wells:318' plywood, 2 x 4's on 24' centers with 31efiberglass batts, 1/2' bead board Glazing Rafters:Double 2 x 4's on 34' centers, plywood gurisets at south roof edge Roof: Same as tilted south glazing COSTS Materiels:$780 ,BullderAllen Grogan

45 , OwnerPulaski County-Council on Aging Location:Community Center, Little Rock Length:27'-10" Width:8 Area of Floor216 eq. ft. Tilted Smith Glazing: 144 sq. ft. Type: ,34" x 76" double glazed teiripered glass panels Vertical South Glazing:81 sq. ft. Type:.34' x 361 awning Windows with double steength glass and an inner layer of,clear vinyl East Vents:8 sq. ft. Type:Upper wall vent West Vents:20 sq. ft. Type:3' x 6'-8" door and screen door Roof Vents:Four 12" diameter turbine ventilators with interior shutters Openings to Building:48 sq. ft. ThertharSterage: -Eighteen 55 gallon barrels of water (82566 lbs.) along north wall and south knee wall, an existing 1' thick solid brick wall and 162 cubic feet of soil (8000 lbs.)

Planiing Arrangement:Upper arid lower beds, (24' wide and 12" deep) along the knee wall and a similar bed above the barrels on tirmorth wall for a total of 162 sq. ft. CONSTRUCTION

Floor, 4° of pea gravel Foundation:An 8° x 18' poured concrete grade beam, with 2"-bead bdard on the inside surface Side Walls:1 x 6 pine siding, 1' bead board, 2 X 4's on 16" centers with 31/2' fiberglass batts, 4 mil pol ethylene vapor barrier, and 3/8" plywood Glazing Rafters: No. 2 double 2 x 4's on 36' cjenters Roof:" phalt shingles, 15 lb. felt, 1/2" CD plywood, 2 x 6's on 24" centers with 6' fiberglass batts, 4 mil vapor barrier, 3/8" plywood ,,

, COSTS Materials: $3000 tBuilderGeorge Flake (supervisor) and the Opportunity Industrialization Council weatherization staff , o

Owner: Sam and Helen Armstrong "\ Location:Rogers - Length:27'10° Width:8' AA of Floor:222 sq. ft. :lilted South Glazing:162 sq. ft. Type:34" x 76" tempered glass panels with an inner layer of vinyl storm windows in wintef Vertical South Glazing:None East Vents:8 sq. ft. iType:2' x 4' upper wall vent West Vents:20 sq. ft. Type:3' x 6'-8" door with screen door Roof Vents:None OpenIngs to House:30 sq. ft\ TYpe:a 3' x 6'-8" glass door and two 10 sq. ft. double hung wood windoOs t Thermal Storage:Fifteen 55 gallon barrels of water (6881 lbs.) stacked against the house wall Planting ArrangeMent:128 sq. ft. of shelves for trays and pots; upper andlower shelves along south knee wall and staggered shelves and hanging pots along the house wall Shading:A polypropylene shade cloth rated at 50% light transmission . CONSTRUCTION Floor:4" pea gravel Foundation:A 6" x 18" poured concrete grade beam with 2" bead board insulationon the outside surface Side Walls:1 x 8 pinesing,1/2" fiberboard sheathing, 2 x 4's with 31/2" fiberglass batts, 4 mil polyethylene vapor brier, 1/2' sheetrock Glazing Rafters:No. 2.pine double 2 x 4's on 36" centers Roof:asphalt shingles, 15 lb. felt, le CD plywood, 2 x 6's on 24" centers with 6" fiberglass batts, 4 mil polyethylene vapor barrier, 1/2" sheetrock COSTSo Materials:$800 Labor Cost:$800 (includes cost of building new door into house) Builder:Joe Henry r0 Owner:Ralph Nesson and Kate Conway Location:Fayetteville Length:16' Width: 10' Area of Floor:160 sq. ft. Vertical South Glazing:90 sq. ft. East:40 sq. ft. Type:34° x 76" tempered glass panels South Vents:15 sq. ft. Type:34" x 12" lower wall vents East Vents:26 sq. ft. Type:3' x 6' x 8' door and two 36" x 12" lower wall vents West Vents:None Rpof Vents: None Oenings to House:20 sq. ft. Type:6' x 6'-8" sliding glass door Thermal Storage:Five 55 gallon barrels of water (2294 lbs.) and an existing 4° concreteslab Planting Arrangement:Flats on top of the barrels and shelves on north wall Shading:None required for vertical glazing CONSTRUCTION Floor: ..Existing 4" concrete lab (previously a garage) Foundation:Existing edge of slab floor Side Walls South and East:4 x 4 cedar posts on 36" centers with the temperedglaés panelsin between Roof:Existing garage roof of 2 x 4 trusses on 24" centers with 6"fiberglass batts COSTS Materials:$500 Labor Cost:$800 BuilderJoe Henry o

48 -o

kA\A

Owner: Ofte of Human Concern, Inc. Location:Siloam Springs Child Development Center Length:18',10" Width: Area of Floor:144 sq. ft. Tilted South Glazing:108 sq. ft., 34" x 76 tempered glass panels with-an inner layer of clear vinyl storm windows in winter Vertical South Glazing:None East Vents:20 sq. ft. Type:3' x 6'-8 door with screen door.. West Vents:12 sq. ft. Type:3' x 4' kid's door Vents:Two-10' x 12° round thermal chiminies with interior shutters Openings to House: One 350 CFM blower on a thermostat for air delivery and a 6" x 24' lower vent by return air Thermal Storage:Nine 55 gallon barrels of water stacked against north wall Planting Arrangement:54 sq. ft. of south ground bed and 72 sq. ft. of stepped pallets (for seedling trays) against north wall Shading:There is partial shading ffom nearby trees in summer CONSTRUCTION Floor:Earth ,Foundation:4 x 4 treated Cedar posts every 3'; 1 x 6 cedar boards on each side with 31/2" fiberglass insulation between posts. Tar and felt waterproofing Side Walls:1/2 ' plaster on metal lath, 1' bead board, 2 x 4's on 16" centers with 3W filerglass, 6 mil polyethylene vapor barrier, 1' bead board, and 1/2' plaster on metal lath Glazing Rafters:Dou6le 2 x 4's (No. 2 pine) on 36" centers Roof:Asphalt shingles, 15 lb. felt, 1/2 'CD plywood, 2 x 6's on 24" centers with 6' fiberglass, 6 mil polyethylene vapor barrier, 1/2" plaster on metal lath COSTS Naterials:$750 Builder:Joel Davidson, Steve Mescha, and Robert Knapp of the Office of Human Concern

49 - Owner -Sebastian County Roads Department Location:. Road Maintenance Building,GreenWood Length:20'-7" Width:8'-6" Area of Floor 160 sq. Tilted South Glazing:160 sq. ft. Typet x 91' tempered glass panels with aninner layer of 6 mil polyethylene in winter Vertical South Glazing:50 sq. ft. Type:3' x 21-6' aluminum sliding glass windows for a total vent area of 25 sq. ft. (screened in summer) East Vents:8 sq. ft. Type:2' x 4' upper wall vent (with screen) West Vents:20 sq. ft. TYPe:3' x 6'-4" door with screen door Roof Vents:None Openings to House: One 350 CFM dust fan on athermostat delivers air to an office area through two 6' diameter ducts. Returireato is from one12' diameter duct Thermal Storage:Ten 55 gallon barrels of water (4565 lbs.), existingbrick wall, 4' concrete slab floor, and 2500 lbs. of soil In planting beds. Planting Arrangement:Upper and lower beds along south knee wall (33 sq. ft.each) and a bed above the barrels along the north (existIng) wallfor a total of 105 sq. ft. of planting beds Shading:a polypropylene shade cloth rated at50% light transmission Is secured to the outside of the tilted glazing in summer CONSTRUCTION FloorExisting 4' concrete slab Foundation: Two courses of 4 x 4 cedar posts attached toexisting slab with lag bolts every 4' Side Walls:Us° masonite siding, 1' bead board, 2 x 4's on 16' centerswith 31/2' fiberglass, 6 mil polybthylene vapor barrier, 1/26 sheetrock Glazing Rafters:No. 2 pine double 2 x 4's on 48' centers Roof;asphalt shingles, 15 lb. felt, 1/2' CD plywood, 2 x 4's on24° centers with 31/2" fiberglass, 6 mil polyethylene vapor barrier, 1" bead board,1/2" sheetrock COSTS Materials:$848 (barrels and some lumber supplies weredonated) BuilderMonica Rojek of Community Energy Futures, Inc. (supervisor) andthe Sebastian County Roads Department staff

50 III.SOLAR AIR HEATERS

A.FUNDAMENTALS \

Solar air heaters are simple devices' pand and rise out of the collector and that utilizp solar energy to help heat into the house through an upper vent, buildings in winter. Air heaters are thus drawing cooler room air into the probably the lowest costing and most collector through a lower vent. Al- efficient solar device you can build to though active solar air heateratre- reduce home energy costs. quire electricity to operate, they are The basic-principles of all solar air still very simple and generally will heaters are the same. A black-painted deliver more BTU's per dollar than piece of metal, called the absorber, is passive solar air heaters. mounted within a shallow frame. Solar air heaters can be further Next, the frame is covered by a sheet categorized as either modular or site glazing +(glass or fiberglass), which built. Modular solar air heaters refer faces south. As sunlight passes to small (usually 4 ' x 8 ') units that through the glazing and strikes the provide heat for a room that is used in absorber,itcauses the black ab- the daytime. Site-built solar air heat- sorber to get hot; much hotter than it ers operate the same as modular air would if there were no 'glazing. Air is heaters, but they are larger (8 ' x 8 ' or drawn from inside the house, across . 'bigger) and are. moreeconomically the absorber, where it picks up heat, built in place at the site. Typically, and then back into the house. During site-built solar air heaters cover most its circuit, the air will rise in tempera- _of the south wall of a home to provide ture anywhere from 20° F to 30° F. a large portion of the heating needs. The frame, the absorber, and the glaz- Since large amounts of heat are pro- ing make up what is called a solar air duced, ducts are often used to dis- collector. tribute the heat to various rooms, and Most solar air heaters built in Ar- sometimes thermal storage systems, kansas are active collectors; that is, Such as rock, beds, are utilized to they use an electrical fan (blower) store excess heat for use at night and that is thermostatically controlled to on cloudy days. blow air across the absorber when it New Life Fprm, Inc. (Drury, MO is hot enough to produce heated air. 65638) has built many site-built solar, SPlar air heaters can also be, passive, air heaters throughout the Ozarks. relying only on the principal of gravity Their manual, "Simple Solar Air Heat- convention or therruosiphoning, ers," by Ron Hughes, ($3.50) is an ex- which is the natural movement of air cellent reference fôr learning the due to differences in temperature. As Many different possibilities for adapt- the sun heats the absorber, the air ing air heaters to homes and other around it gets hot, causing it to ex- buildings.

51 -1111111,-

The Office of Human Concern (OHC) of Rogers has conducted twenty solar air heater workshops for individuals,vo-tech sChools and community agencies throughout Arkansas.The 4 ' x 8' collector shown here is being installed by local residents onto a community center in Gravette.

52 Construction of the O.H.C. solar air heater reqoires only simple carpentry skills. In ttie photo above, the absorber (aluminum roofing) is being fitted within the collectorfrome during a construction workshop in Blytheville.

53 B.MODULARSOLAR AIR HEATERS

Modular air heaters haye been ideal 3. Delivered and in less for the purposes of several commun- than a day. ity agenàies in Arkansas who have built and installed over 100 units on Completely automatic. the homes ofelderly, low-income families during the past two years. Durable enough to last at least The first modular solar air heater in 10 years without maintenance. Arkansas, and the standard by-which most others have been built, was de- Figure p-i illustrates the construc- veloped by Joel Davidson and Bill tion of the collector, which is mount- Brown of the Office of Human ed either vertically or horizontally Concern (OHC) in Rogers. They saw a against the south wall of the house. need for air heaters as the next logi- The area between the absorber and cal step to reduce fuel consumption_ the glazing is a dead air space which in homes that had already been wea- is vented in summer by thermostatic vents to prevent overheating. The air ,therized. Their objectives were to design a low-Cost, solar air heater that flows through a 11/2 " x 24" air gap could be: behind the Corrugated aluminum absorber. (The depth of 11/2" includes 1. Built in quantity with simple the depth of the corrugations.) A 200 carpentry tools and skills. CFM 6quirroicage blower pushes the air in a U-shaped path around a center Assembled easily and cheaply baffle for a total air run of 16 feet. by using standard 4 x 8 corn- . 4im Free, of the Crowley's Ridge ponents for the glazing, absor- 'Development Council in Jonesboro, ber, anld backing. has designed a variation of the OHC

FRONT I x 4 FRAME REAR AIR BAFFLE METAL ABSORBER AIR PASSAGE AIR VENT AIR VENT F1LON GLAZING

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54 COLLECTOR ON SOUTH SIDE OF HOUSE

HOT Al INTO HOUSE-

FIG. B-2 collector. Air is blown both in front of of 425 to 600. and then behind the absorber for a Each of these three collectors total run of 32 feet. To compensate costs about $110 if the components for the increased distance of air flow, are bought at wholesale prices and the air gap has been increased to about $150 if the materials are bought about 1-1/2 " on each side of the ab- at retail prices, as they would be for sorber. Jim recommends a 200 to 350 homeowners who wish to build one CFM blower, or more units for themselves. AOee, Another modular solar air heater illustrated, step-by-step manual on based on the OHC model has been constrUction, opecation, and perform- developed by Peter Scholls of the ance of the OPIC collector is available Crawford-Sebastian Community De- from the Office of Human Concern, velopment Council in Van Buren. This P.O. Box 756, Rogers, Arkansas unit is identical to the OHC version 72756. A similar construction guide except that a 10" propeller-type duct of Jim Free's collector design is avail- fan instead of a squirrel cage blower able from the Crowley's Ridge De- is used. The duct fan has the advant- velopment Council, Jonesboro,Ar- age of fitting flush within the wallfor kansas. more quiet and unobtrusive opera- Larry Bueg, of the Energy Center?, tion. Since propeller-type fans have Inc. in Lowell, recently designed a 4 ' less power than squirrel cage blowers x 8 ' modular solar air heater that is to force air through the collector, the quite different from any built in Ar- duct fan requires a higher CFM rating kansas. As shown in Figure B-2, this

6 5 unit mounts directly into the lowor the collector. part of, a south window, eliminating It was found that much more air is the time and expense, of putting delivered to the room when the ducts through the wall. Inttead of blower is mounted on the delivery being mounted flush against the wall, side of the manifold rather than the this collector has brackets which can intake side. 4adjust the collector to the optimum The collector is framed in sheet angle for,solar collection in winter. metal with a fiberglass glazing, The absorber, which also serves as making it very lightweight and wea- the insulation and back of the collec- therproof. In slimmer, the unit can be is a 4 'x 8 ' x 1" sheet of rigid, easily removed from the window and igh-temperature fiberglass.Black stored in the garage or, better yet, aluminum foil covers the fiberglass to can be utilized as a solar fooddryer. serve as the heat-absorbing. surface. The collector can be fitted to a cabinet Galvanized steel baffles create a ser- with vertically arranged screen trays pentine air flow in front of the ab- upon which the food is placed.Solar sorberJotal length of air run is 32 ', heated air is blown through the cabi- with an air gap of 2". net, thus drying large quantities of The manifold that projects through food very rapidly. Arkansas families the window is divided into two halves, who traditionally use canning as a one side serving as the air intake into means of preserving food could in- the collector and the otherside hous- stead use such a device to solar dry ing a small squirrel cage blower. Un- their food, saving much time and like the arrangements in the previous- energy. Also, ciried foods have super- ty mentioned collectors, this blower ior taste and nutritional value over pulls Instead of pushes air through canned foods.

C. PERFORMANCE

There is an urgent need to compare the HC collector. The following is the performance of these collectors an exe.rptjom the OHCair heater in side-by-side tests so that effective manual that describes the results of improvements xan be made in their tests Conducted from October 10, design. To date, all the design criteria 1979 to February 26, 1980: . have been based on research and ,"Ten homes occupied by low- demonstration projects by the San income elderly people in Benton, Car- Luis Valley SOlar Energy Association roll and Madison Counties were fitted (P.O. Box 1284, Alamosa, CO 81101) with solar air heaters in September of and the Small Farm Energy project 1979. Seven of the homes were (P.O. Box 736, Hartington, NB 68739). heated with natural gas and three of These two non-profit organizations the homes were heated with propane. have developed the rules-of-thumb (Wintertime) fuel consumption for for solar air collector design that have each home from 1977 to 1980 was ob- been used successfully throughout tained from fuel suppliers (Arkansas the country. Western Gas and Sungas). Although precise scientific mea- In the test homes, the dollar sav- surernents have not been made to ings (caused by theairheaters) compare performance among the air ranged from 6.3% to 13.44% with an heaters, studies have been done to overall average of 9.87%.itis ex- assess the general effectiveness of pected that this figure will increase

6,1 56 ,with the u e of the larger blower (200 The value of. 2,190,816 -BTU's of CFM),anci he addition of an adjust- heat for houses that use electricity, able ther ostat that will extend the natural gas or propane to heat their

daily ho rp of operation." homes in 1981, is: The cjeçision to change to a 200 CFM bl Wer was a result of the tests Electricity condu ted in January of 1980 by Dr. 2,190,816 BTU = 641 Kilowatt/Hours Thomas Rokeby, a consulting engineer At 60 per KWH, you save who is director of the solar poultry .06 x 641 = $38.46 house project at the University of Ar- kansas in Fayetteville. He tested sev- *Natural Gas eraldifferent sizes of blowers to 2:190,816 BTU = 2.12 MCF determine air flow characteristics of At 3.50 per MCF, you save the airheater and cOncluded that the 2.12 x 3.50 x 1.30 = $9.65 larger blower would increase heat produotion by about 38%. *Propane Gas More tests.were performed on theq 2,190,816 BTU = ,23.8 GAL OHC air heater in December of 1980 At .80 per gallon, you save by Russ Garton and Steve Metcalf, 23.8 x .80 x 1.30 = $24.75 graduate students in mechanical en-. gineering at the University of Arkan- Whereas electrical heating is 100% sas in Fayett9ville. They determined efficient, you only get about 70% of the average efficiency of the collector the BTU's available in eaoh unit of to be 48.5%, which is very good when gas (the rest goes up the flue). So an compared, to simiiar air heaters built efficiency factor of 1.30 is included in by the Small Farms Energy Project the value of each unit of gas that is and others. saved by solar energy. For Little Rock, a vertical south- facing surface will receive an average If you spend $150 to build an air of 152,140 BTU/ft2 total solart. radia- heater and take the 40% federal tax tion during the heating season (No- credit, the actual cost is only $90. vember to March). Therefore, a col- With prices of electricity, natural gas lector of 32 square feet and 45% ef- and propane rising dramatically, an ficiency would deliver: investment in an air heater will pay for itself in two to five years. 152,140 BTU/ft2 x 32 x .45 = 2,190,816 BTU

D. DESIGN METHODS The basic rules of the thumb for de- it has gone through the collector. This signing solar air heaters are: capacity will be less than the free air . 1. The baffle layout in the collec- rating of the fan because of the resis- tor should be such that no single air tance encountered in the collector. run, the distance between the inlet The average air flow reduction, called and the outlet, exceeds 32 feet. the static pressure drop, across a typical solar air heater is rated at .5 on 2. The "delivered" air flow should an instrument that measure's pressure 'al 3 CFM per square foot of, col- change in inches of water in a column.

tor. The delivered (or actual) air flow , Most fan and blower CFM ratings are is the fan's rated capacity (CFM) after given for both "free air" conditions

57 and over a range of pressure drops. area (in square feet) of the air gap ratings are given for both "free air" cross-section. The gap is then found conditions and over a range of press by dividing the cross section area by sure drops. the-width of the collector air way in For example, the delivered, aic--ffew one direction of airflow. through a 32-square-foot collector For example, the free air rating for should be:3 CFM .x 32 = 99 CFM. a 32-square-foot'collector was deter- Since it is assurned that the pressure mined to be 200 CFM. So: drop will be about .5 inches, the rating for the fan at a pressure drop of .5 200 CFM 800 FPM = inches should be at least 99 CFM. ,.25 square feet or 36 square inches. Most squirrel cage blowers with a free air rating of 200 CFM will have a Since the air way width is 24 inches, delivered air flow Of 100 CFM at a the gap is pressure drop of .5inches. 3. The air gap is a function of the 36 24 = 1.5 inches. air flow (Cubic feet per minute) and the air velocity (feet per minute). The If corrugated roofing is used as the assumed optimal air flow is 800 FPM absorber, as in the OHC collector, the (Feet Per Minute). Divide the free air depth of the corrugations must also CFM rating by 800 FPM to get the be counted as part of the air gap. IV.BAMIT SOLAR WATER HEATERS

A.INTROQUCTION - Historically, solar water heating A recent publication titled "Solar has beeil the most practical and wide- Hot Water," by Nicholas Brown, ex- spread of all solar applications. The plains a wide variety, of owner-built amount of effort that people have solar hot water systems and how they spent on solar water heating has cart be built using common plumbing been proportional -to the availability supplies and off-the-shelf compon- of fossil fuels aril the severity .of the ents. This booklet is available free climate. Evidence of solar water heat- from the Arkansas Energy Office and ing methods dates back thousands of should be read prior to this repdrt by ears to the early days of the Greek those unfamiliar withsolar water a)id Roman civilizations. today, the / heating concepts. This retrofit guide 'countries of Japan and Israel obtain a' .focuses on batch solar Water heatere large percentage Of, their hot water because they,offer the most potential _needs from the sun; also, the majority for immediate and widespread use on of companies iii-the solar industry are homes in Arkansas. exclusively involved w,ith solar water When rubst people think of solar heating systems. water heatihtrthey think of solar col- Although solaPtvater heatere are lectors mounted on rooftops. Flat common in 'many parts Of the world plate collector systems have received and are even requirecby law in a few most of the solar publicity and ere the American cities, they arb nal preva- predominant method of solar water lent in Arkansas. One reason for this heating today. However, the batch is that most Arkansans, like most solar water heater is far more simple Americans, believe thatallsolar to build and operate and, with the ad- water heaters are complex and expen- vent of new designs., can be as effec- sive. It is frue that most cbmmercially tive as a flat plate collector system. available systems cost from $1500 to the operation of a batch solar $3000, which makes them unafford- water heater is very simple:no able tor most residents, even consid- pumps, no heat exchangers, no con- ering the 40% federal tax credit. But trols or other moving parts. The sun there are simple, owner-built, solar shines through a glass cover onto water heating systems, called batch black metal tanks inside an insulated Vi water heaters, that cost less." than box, heating the Water in the tanks. $300 and have been demonstrated in Thus, the heat dollection and storage Arkansas to save about 50% of the IlInctions of the water heater are yearly hot water costs for a typical grated.' household. The cold water line in the house is

6 7 59 ,plumbed to, the tpnks so that water been shown to be the most effective must pass throUgf7i the tanks before it solar heating system on a BTU per enters 'the conve'ntional hot water dollar basis.._,Currently, most operat- heater Nthe houe (Fip. A-1); hence ing batch water heaters are home- the term l'Preneater" is sometimes built systems constructed from inex-- used to describe batch solar water ',pensive materials, such-as recycled heating systems. water heater tanks. In Most oases, the In wi6ter, the tanks may be drained batch sélar pater heater will be the to prevent the water from freezing. cheapest soldr water heater for home- However, recent designs employ in- owners to build and operate. How- sUlated shutters that are cloSed over ever, it also has good potentialfor '.the tanks at night to extend the effec-: productionbylocalplumbing tive peri6d of operation. , businesses for new or existing Many people have trouble believing hornes, schools, and commercial' ethat ibch a simple concept can work buildings. yery wbIl, but batch heaters have BRIEF HISTORY iginally,batch water heaters rapidly. But with three separate tanks, were nothing more .than a black- it taket much longer for the incoming painted tank of water exposed to the wafer to mix, and more hot water can sun. The name comes from the fact be delivered. Brooks concluded that that all the water is heated at once, in batch- water heaters were effective a batch. These simple heaters were solar energy absorbers but-were poor built by the thousands in' California for storing hot water overnight. and Florida in the late 1800's when Batch Water, heating design _was heatingLfuel_waS_sc-arceLand expen- largely forgotten In this country. until sive. The tanks supplied hot water by 1972, when Steve Baer, a solar re- late afternoon and only during the searcher in Albuquerque, New Meid- , warmer months, -but could cut hot co, built and tested his"breadboxv water bills by-75% in the summer and water heater (Fig. B-1). The breadbox 25-50% year round, (so called because it looks- like one) In 1891, a patent!wp awarded for added insulated shutters which, the "Climax" solar water heater, when opened, reflected additional which was thefirOt comMercially sclar energy onto the tanks and, made batch water heater to enclose when closed at night, insulated the the tank inside a glass-covered box. tanks to prevent rapid heat loss.'On a The glass served to trap heat radiat- clear February day with an average ,ing from the tank, and performance outside (ambient) temperature of was dramatically improved over the 40° F, 60 gallons of water in two tanks bare designi Batch water heaters per- in,the breadbox were solar heated ini- formed ,well -in those early days but tially. to 140° F_,and were lowered to gradually disappeared ..as artificially only 107° ,F after 35 gallons were cheaphatural gas and electricity be- drawn. cameavailable. Ken Butti and John in 1979, Allen Grogan, of North- Perlin describe thi,s history, in their west Arkansas Economic Develop- book, The Golden Thread. ment District; ln. in Harrin, de- F. A., Brooks tested several batch signed a two-tank batc water Iheater. water heaters in 1936 at the -Univer: Several units were bui t as p rt of a sjty of California. He demonstrated CETA training prograand istalled that tanks in glazed*iritulated boxes on the, homes of low-inCome, elderly are capable.of producing hot water at residents. Although no scientific over 120° F. He also proved the ef- monitoring has been done, Ihe fectiveness of using these tanks in owners have experienced a reduction series as opposed to one tank. As hot in, their fuel bills. However, the design water is drawn out of the upper-part called for 5-foot wide - fiberglasS, of the tank, cooler water enters which must be ordered in quantity from the other end and mixesvith the and makes it impractical for individ- solg heated water, causing it to cool uals who wish to build just one unit. REFLECTIVE SHUTTER GLASS

SOUTH BREADBOX FIG. 13-1

C.A. NEW DESIGN,

As with solar greenhôusqsi and 1) It is kep4 in stock as a stan a I solar air heaters, it is yen) impoitatit replacement fbr sliding glass door to design owner-built solar water and can be bought locally through° t heaters to use only standard, locally Arkansas. ($20-29 for single panor available materials that reqUire a $60-65 for double pane) minimum of modification to, asserrible. 2) Itis long - enough and wide The main components of the batch enough to enclose two typical heaters are the absorber (tanks), the recycled gas or electric water heater glazing and the box. They heed to bir tanks. , . rnatched in size so there is little or no 3) It will not degrade under sun- wa§te of materials. light. COnsiderring that prewous. tatch _4)Jt has a Very _high IMPact solar water heater-designs required strength io resist damage by hail and custom-glazing,I designed a batch other objects. water heater that uses a standard tempered glass panel,-(34" x 76") as- The tanks are mounted within an the primary component. This glass insulated plywood box. The box is panelis the main element in the then mounted, on a wooden stand at design, around which all other parts- an angle of 45° from horizontal. This are built because: is the optimum angle to collect solar gpii. I. ....Nil %Ph.. L ," 1 itidAiran4A411.1C

C"..t

This new batch water heater design, called the Sun Mummy, uses only three Neets of plywood to construct. The insulated cover (shown closed) has a continuous piano hinge along the bottoM for easy opening and closing.

r .1AT .1

1 I t !: 4

When opened, the tanks of water are heated lay direct sunlight and by reflected sunlight from the cover. The length of the chains oh each side of the heater can easily be adjusted to re-position the , cover as the seasons change.

(7- t?

energy on a year-round basis. An (C.E.F.) a non-profit energy research adjustable insulated plywood cover is arid training_ agency, has built ahd Tlinged to the bo)qo reflect additional' tested sevei51 prototype units of this energy onto the tanks during the day, design in Blytheville, Little Rock', and and is closed at night to store the Dumas. Preliminary performance heat. Total materials for the collector tests by Aviv 4Goldsmith of C.E.F. cost about $175. The cost of pipe and indicate that fhese waler heaters,--4/ fittings "to connect the collector to would be effective in Arkansas for 7- the existing water heater utually runs 10 months ouj. of the year and have a about $30-50. pay-back WO of less than two years Community EnergyFulures, Inc., for most homes.

D. PERFORMANCE

The May-June 1981 issue of New such as the one we' showed in our Shelter magazine gave the results of October 1980 issue. Once the conser- extensive, year-long tests on five dif- vation measures are in place, a batch ferent,types of home-built solar water heater,can cut your remaining water- heaters. Systems includedin the heating cost by a full third, saving a study were batch, thermosyphon, total (conservation plussolar) of $289 drain doWn, drairi back and phase per year. At this rate, the combined change. The systems were cOmpared return on investment is 65 :per Cent for their performance in BTU's per per year, with a pay back of lust a square foot, cost per BTU, return on year-and-a-half. You ca'n't do Much investmeieand ease of construction. better .than that.. families' in The summary of the results states:* most parts of the nation, the batch Without a doubt, the batch heater heater offers, the best combination of seems the best choice of the solar loW cost, ease of assembly and high iser§tems. It's simple and inexpensive; performance.Itgets our highest it offers a very high return and a low recommendation. It worked well for Cost-per-BTU; and it pays fc}r 'itself us here iD,Pennsylvania, and it should quickly. It's also architectu011y flex- work even betterjor those of you who ible:if you have a sunny wall, fou liveln the South, Southwest, or along can integrate thel heater _into your the West Coast. You get mdre sun home's siding, giving the system a than we do, and you can operate your pleasing leeiltin" appearance. Or, if batch heater year-round without fear your hom faces the wrong way, you of freezing." can build a free-standing version,

64 LIMITATIONS Batch solar water heaters are gen- heating system to consider is a recir- erally the first option to consider culatng system. For specifics on this when choosing among solar" hot system, refer to the Arkansas Energy water heaters, but there may be good Office's publication, "Solar Hot reasons why they are not suitable to Water," by Nicholas Brown. everyone's needs: 1) There may not be shade free areas on the south side of the house NOTE:It is foolish to consider any 'to acCommodate the heater. solar hot water system unless you 2) %though batch heaters oper- have already employed conservation ate well without a_ shutter, maximum measures on your existing hot water performance is obtained only when system. Turning down the tempera- the owner can open and close the ture control on your water heater to cover on a daily basis. To most 120° F and installing pipe and water people, this is very little effort. But it heater insulation, flow restrictorS, may be difficult or impossible for and a timer on your electric water some-elderly or handicapped persons. heater will save far more, energy per In case the batch water heater is im- dollar invested than 'any solar system. practical, the next type of solar watts r APPENDIX A-GLOSSARY

Absorbe PlateA black surface that absorbs occurs during periods of cloudiness or insolar radiation and converts it to heat; a corn- tense cold, when a solar heating system can- ponent of a flat-plate collector, not provide enough heat to meet the needs of the space. Absorptance The ratiobetweenthe radiation absorbed by a sUrface and the total AzimuthThe angular dittartce between energy falling on- that surface. A flat black true south and the point on the horizon di- surface, such as used in solar collectors, has rectly below the sun. a high absorptance. BermA mount of earth either abutting a Absorption Chilling --Solar assisted; An air- house wall to help stabilize temperature in- conditioning method that uses solar heated side house, or positioned to deflect wind liquid to activate the chilling process. from house. Active SystemA solar heating and/or cool- British Thermal Unit (BTU)The quantity of ing system using mechanical methods of heat required td raise the temperature of 1 heet distribution. pound of water 1 degree F°. One BTU = 252 calories. Air-Type CollectorA solar heat collector designed to use air as heat-transfer fluid. CalorieThe quantity of heat needed to raise the temperature of one gram of water Alternating Current (AC) Electric current . one degree Celsius. which changes its direction of flow at regular intervals, normally making 60 cycles per. CaullOngMaking an airtight seal by filling second. AC is easier to transmit than direct in cracks around windows and doors. current and is also more easily changed to higher or lower voltages. Household current Centrifugal PumpA high speed pump that is AC, drives water with a rotating impeller. Ambient TemperatureSurrounding temper- ClerestpryVertical window placed high in ature, as temperature around a building. wall near eaves, used for light, heat.gain, and ventilation. 4 Ampere (AMP)The unit of rate of flow, in an electric circuit. Closed LoopSystem inwhicd-4at-transfer liquid from collectors circulates through a Ampere-HourUnit of electrical charge, heat exchanger immersed in heat-storage equalling the quantity of electricity Wowing liquid, passing its heat to heat-storage liquid in one hour past any point of a circuit carry- while remaining isolated from it. ing a current of one ampere. Storage batter- ies are rated in ampere-hours to show the Coefficient of PerformanceRatio of heat quantity of electricity that can be used with, output to energy use of a heating or cooling out discharging the battery beyond sae device. limits. Coefficient of Heat Transmissio nThe rate Angle of IncidenceThe angle at which radi- of heat loss in BTU's per hr through a tant energy strikes e Surface, measuring from squar'e foot of wall or other ilding4surf ace the path of the energy tcra line perpendicular- when the difference between indoor anclotitz to that surface at the point of impect. The door air temperatures is one degree Fahren- angle of incidence determines the percent- heit. ege of direct sunshine interruptedby esur- , face. The sun's rays that are perpendicular to CollectionThe aqt of trapping solar radia- a surface are said to be "normal" to that sur- tion and convertinceit to heat. face CollectorAny of a variety of devices used Auxiliary System (Back Up)A supplementary to absorb solar radiation and convert itto heating unit to provide heat to a space when heat. its primary unit cannot do so. This usually 7" 66, Collector EfficiencyRatio of collector heat wood tar that may collect on the walls of a output. to amount of solar radiation that chimney as a result "pf incomplete combu- strikes collector apperture. sion. Also Used to*treat lumber to resist moisture. Collector TiltThe angle between the hori zontal plane and the solar collector plane. Dead Air Space (Vapor Elarrier)A confined 6 space of air. A dead air space tends to reduce "Collector, SolarA device for capturing both conduction and convection of heat. This solar energy, ranging from ordinary windows fact is utilized in virtua4all insulating mater to complex mechanical devices. ials and systems, such as double glazing, beadwall, fiberglass batts, rigid foam panels, Combiqed-Energy System-- A. 4:Ham-that u ti- fur and hair, and loose-fill insulations like ize s several sources of energy in the most pumice, vermiculite, rock wool and goose efficient way. down. Concentration CollectorDevice that uses DeciduousSpecies of trees whichsiffed reflectors to concentrate direct solar rays their leaves in the autumn, onto a narrow absorber area to prod)uce in- tense heat, Degree-DayAn indication of heatingneeds', based on the difference between the averag ConductionThe ffow of-heat due to temper- daily ternperature and an assumed steady i 'ature variations 'within a material (solids, door temperature of 65 ° F, A 24.hour peri d liquids or gases). with an average temperature -of 60° F rat s five degreedays; a daily average of 60° F ConductanceThe rateof heatflow(in rates 65 degree-days, Degree-days are then BTU's per hour) through an object when a 1' totaled tb obtain seasonal or yearly heating F. temperature difference is maintained be. needs,

, tween the sides of the object, Demand LoadDomestic water heating Condudtivity (k-Value)A measure of the needs to be supplied by solar or conventional ' ability of a material to permit conduction energy, heat flow through it. Demand TimeOccurs when energyis ConifersSpecies of trees which usually needed, as heat is at night, keep their leaves in the autumn, including the evergreens. Density-The mass of a substance which is expressed in pounds per cubic foot. Convection, NaturalHeat transfer throUgh a fluid (such as air or liquid) by currents re- Design TemperatureA designated temper. sulting from the natural fall of heavier, cool ature close to the most severe winter or sum- fluid and rise of lighter, warm fluid, mer temperature extreme's of a climate, used in estimating a house's heating or cooling re- Cooling SeasonPortion of year (usually quirements, June to September) when outdoor heat makes indoor cooling desirable .to maintain DesiccantA coarse, salty or sandy sub- - comfort, _ stance such as calcium oxide or sulfuric acid "- that is used to absorb moisture,.both in liquid Converted HeatHeat which is transferred and v.aporous forms, kom one position to another, driven by the change in a gas's density that accompanies a Differential ThermostatAutomatic device change in temperature. that responds temperefuie- differe-n-déi (between collectors and heat storage. for CordA unit, of volume measurement 4 x 4 example) in regulating dperation of an active x 8 feet, generally used to measurequanti- solar system, ties of wood cut for fuel. Diffuse RadiationSolarfadiation, scattered Cover PlateA sheet of glass or transparent as it passes through atmospheric molecules, plastic placed above the absorber in a flat- water vapor, dust, and other particles, so that plate collector. (See Absorber and Collector.) it appears to come from entire sky, as on a hazy or overcast day. CreosoteAn oily, odorous distHlate of

67 Direct Current (DC)ElectriC current which Flat Black PaintNonglossy paint. with a flows in one ,direction-, Generators produce' relatively high absorptance. DC current. Flat-Plate CollectorDevice that employs a Direct-GainPassive solar heating system planar absorber plate to collect solar radia- in which the sun penetrates and warms the tion and convert itto heat, without assis-, interior structure directly, (A window on the tance of devices to concentrate sun's rays. south side, for example,) Flow FthteThe pounds of heat-transfer fluid Direct RadiationRadiation that comes di- which pass over or through an absorber plate-- rectly from sun, as opposed to diffuse or per hour. reflected radiation. Forced ConvectionThe transfer of heat by Domestic Water PressureThe pressure of the flow of fluids (such as air oi water) driven the potable water within the building from by fans, blowers, or pumps. sources not related to the solar domestic hot water system. FreonA volatile chemical substance cap-

able of boiling (becoming . lighter) at low Double.-GlaiedCovered by two panes of temperatures. . glass or other transparent material, Galvanic CorrosionThe condition caused Double Wall SeparationHeat exchangers as a result of a conducting liquid making utilizing non-Potable heat transfer fluids are contact with tWo different metals which are

. separated from the potable Water system by not properly isolated physically and/or elec.-- use of two walls between the fluids. trically. Drain DownFunction of an open-loop solar Galvanized SteelSteel which has been water system in which all water drains out of sprayed, immersed, or electrically, coated the collectors when a freeze threatens, with rust resistant zinc. Elliciency-r-A measure of how much of (the Getters (Sa6rif1cial anodes)A cOlumn or energy applied to a device isutilizedin cartridge containing an active metal which useful work. will be sacrificed to protect sdme other metal in the systentagainst galvanic.corrosion. EmittanceA measure of the ataility of a material to give off thermal radiation. GlazingA covering of transparent or translucent material (glass or plastic) used for ad- EnergyThe ability to do work. Units of mitting light. Qlazing retards heat losses energy are:kilowatt hour (KWH); British from (eradiation and copvectfon. Examples: ihermalunit(BTU): and horsepower-hoUr. windows', skylights, greenhouse and collec- (hph) tor coverings. Eutectic SaltsSubstance,s that melt readily Glazing, DoubleA sandwich of two sepa- at low temperatures (as low as 800 to 90° F) rated layers of glass or plastic enclosing air and, in so doing, store large quantities of to create an, insulating barrier. latent heat, which they release when cooling and resolidifying. Gravity convectionThe natural movement of heat that occurs when a warm fluid rlSes EquinoxEither of the two times during a and a cOol fluid sinks under the influenCe of year when the sun crosses the celestial gravity4See_convect4on,) eq"u atorin-clw he-iiih é Le fldiOrdaia-n-d night are approximately equal. These are the Greenhouse Effect-Ability of glass dr clear autumnal equinox on or about September 22 plastic to transmit shortwave solar radiation and the spring equinox which is on or about into a room or collector and to trap long-wave March 22. . heat emitted by room or collector interior. Evaporative CoolingEvaporating water HeaderThe Pipe that runs across the edge cools and humidifies surrounding air: house of an array of solar collectors, gathering (or air is circulated over water as technique to distributing) the heat transfer fluid from or to cool indoor air in dryclimate areas. the risers in the individual collectors. This in.) sures that equal flow rates and pressure are HumasOrganic matter (animal and plant) in maintained. (See Risers.) a state of decomposition, forming an essen- tial element of all fertile soils. Heat Capacity(Volumetric)The number of BTU's a cubic foot of material can store Hybrid SystemSolar heating systerl) that with a one degree increase in its tempera- combines active and passive techniquei. ture. Indirect-Gain SystemPassive solar heating Heat DistributionThe actof conveying system in which-sun-ditettly-warms-a-heat solar heat from collectors . to, storage and' storage element in one area of the building, from storage (or coliectors) to areas of the and heat is then distributed from that ele- building where heat iS needed. ment to the rest of the building by natural convection, conduction, or radiation. Haat ExchangerDevice consisting of a long coil of metal pipe or a multifinned radia- InfiltrationThe uncontrolled Movement of tor used to transfer heat from one fluid inside outdoor air into the interior of a building to another outside, without bringing the two through cracks around windows and doors or fluids into direct contact. in walls, roofs and floors. This may work by cold air leaking in during the winter, or tha re- Heat GainAn indrease in the amount of verse in the suMmer. heat contained in a space, resulting,' from direct solar radiation and the heat given off Infrared RadiatIonElectromag lcradia- by people, lights, equipment, machinery and tion from the sun thatha's Wavelengths other sources. slightly longer than visible light. Heat LossA decrease in the amount of Insolation-70r incident solarradiation: heat contained in a space, resulting from amount of direct, diffuse, and/or reflected heat flow through walls, windows, roof and solar radiation striking a given surface per other building envelope components. hour, Heat StorageA device or medium that ab- InsulationMaterials or Systems used to sorbs collected solar hear and stores it for prevent loss or gain of heat, usually employ- use during periods of Inclement or cold wea- ing very small dead air spaces to limit con- ther. duction and/or convection, Heat Storage CapacityThe amount of-heat InverterA device for converting direct cur- which can be stored by a Material, .rent (DC) into alternating current (AC). r

Hea)ting . SeasonPortion of year (usually Isogonic ChartShows magnetic compass October to, May) when outdoor cold makes deviations from true north, indoor heating necessary to maintain comfort. K-ValueBTLPhr/fP/F ° per inch. (See Con- ductivity.) Hilat-Recovery DeviceA device, designed for installation in a fireplace, through which KilowattA unit of power equal to 1,000 house air or household water is cycled to re- watts. C lai m fire's- heat befpreit c-an escape through,- chimney, Kllowatt.Hour (KWH)The amount of energy equivalent to 1 kilowatt of power being used Heat StorageMedium that absorbs collect- for one hour; 3,413 BTU, ed solar heat, and holds it until it is needed to heat house interior. LangleyA measure of solar radiation; equal to one calorie per square centimeter. Heat.Trinsfer PluldAlr or liquid used to - carry solar heat from collectors to heat stor- Life Cycle CostingA method of cost analy- age. sis in whith operating, maintenance, fuel, and other ownership costs are estirnat\ed for HorsepowerA meaSure of the rate of doing predicted lifetime of a device and considered woi*, equal to 33,000 foot pounds or 754.2 along with initial cost; often used to compare watts. costs of solar heating or cooling systems and conventionally fueled systems.

69 Liquid Type CollectorA solar heat collector RadiationThe direCt transport of energy designed to use a liquid as heat transfer fluid. through space by means of electromagnetic waves. Magnetic South"South" as indicated by a compass; changes markedly from one loca- ReflectanceThe ratio dr percentage of the tion to another because of latitudinal rela- amount of light reflected by a surface to the tionship to Earth's magnetic fields. amount incident. The remainder that is not reflected is either absorbed by the material MicroclimateClimate of a very small area, or transmitted ihrough it. Good light reflec- such as a building site, formed by unique tors are' not necessarily good heat reflectors. Combination of topography, exposure, soil, and vegetation ofsite., Microclimate may Reflected RadiationSolar radiation reflected contrast sharply with macroolimate (regional off surrounding objects soit appears to climate) in which it is situate& come from them, as in reflection off a white viall or a car window. Movable InsulationInsulation placed over windows when needed to prevent heat loss RefrigerantA volatil substance, such .as or gain.and removed for light, view, venting, ammonia, used for obtaining and maintain- or heat. ing low temperatures, as in a refrigerator. Natural Convection (See Gravity Convec- ReradiationRadiation resulting from the tion.) emission of previously absorbed radiation.

Open LoopSystem in which heat-transfer , Resistance or' R-ValueCapability of a sutte liquid from collectors feeds directly into stance to impede the flow of heat. Used tO heat-storage liquid, describe insulative properties of construction materials. Open SystemAn assembly of natural and architectural 6omponents which converts Resistance HeatingA standard method of solar energy into usable or storable thermal converting electricity into heat for the pur- energy (heat) without mechanical power. pose of home heating. OrientationAlignment of a building along a RetrofitTo add a solar heating or cooling given axis to face a specific direction, such system to an existing building. as along an eastwest axis to face south. RisersThe flow channels or pipes that dis- Parabolic ReflectorReflector designed in tribute the heat transfer liquid from the head- the shape of a parabola to focbs extra sun- ers across the face of an absorber -plate. (See light onto absorber of a concentrating col- Header.) lector. R-Value(Seit Resistance.) Pasttive SystemA solar heating and/Or cooling system using natural means of heat Seasonal Efficiency'-a-The ratio, over an distribution. Generally, building's structure entire heating season, of solar energy col- itself forms solar system. - lected and used to the solar energy striking *%. the collector. Payback PeriodPeriod of.tinie a-solarheat- ing or cooling system takes to return Its Selective SurfaceSpecially adapted coat- entire initial cost through fuel savings. ing with high solar radiation absorptance and low thermal emittance, used on surface of an Percentage of Possible SunshinePercent- absorber plate to increase collector efficiency. age of daylight hours during which direct sun . . is bright enough to cast a shadow. SensorDevice that detects changes in heat and relays information to differential therrho- Potable WaterW1ter suitable for people to stet. drink, Shading CoefficientThe ratio of the solar ,PiranometerAn instrument for, measuring heat gain through a specific glazing system solar radiation. (See Solar Radiation.) to the total solar heat gain through a single layer of clear double-strength glass. fir ?CI 70 Skydome (Sky vatalt)The visible hemis- Thermal MassThe amount 'of potential heat phere of sky, above the horizon, in all direc- Storage capacity available in a given as- tions. sembly or system. Drum walls, concrete floors and adobe wells are examples of SkylightA clear or translucent panel set 'thermi rnass. into a roof to adrnitsunlight into a building. Theimocirculation or ThermosiphoningThe Solar. AttitudeThe angle of the sun above convective circulation of fluid which occurs the horizon. when warm fluid rises and is displaced by denser, cooler fluid in the same s*STern. Solar ConstadtThe amount of radiation or heat energY that reaches the outside of the 'Thermal Radlpfions-Electrornagnetic radia- earth's atmosphere. tion emitted by a warm body. (See, infrared Radiation.) Solar HouseHouse that derives aeleast 40 to 50% of its annual heating (or cooling) from ThermistorSensing device which changes the sun. its electrical resistance according to temperature. Used in the control dystem to generate Sotar Radiation (Solar Energy)Electromag- input data on collector and storage tank netic radiation emitted by the sun. temperatures.

Solar Rights (Sun Rights or Solar Access)=A Time LagThe period of time between the legal issue concerning the right of,,accesS to absorption of solar radiatiqn by a material sunlight. and its release into a space. Time lag is an important consideration in sizing a thermal Solar WindowOpenings that are designed storage wall_or Trombe wall, or placed primarily to admit solar energy into a spáce. Tilt AngieAngle at which a collector is tilted upward from horizontal for Maximum Space Heating,Heating of 'the air inside a sqlar exposure. ' building. ("Space.cooling" is the coaverse.) Tra nsluCen The qualityof transmitting Specific Heat (Cp)The number of BTU's re- light but causing sufficient diffusion to elimi- quired to raise the temperature of one pound nate perception of distinct images. of a substance 1F in temperature. Transmittance TFe ratFo of the radiant ener- Stagnation TemperatureHigh temperature gy transmitted through a substance to the range 300 to 400 degrees F; reached inside a total radiant energy incident on its surface. collector on clear, sunny days when the heat In solar technology, it is always affected by transfer fluid isn't circulating through the the thickness and composition of the glass collector. cover platek_on a collector and to a major extent by the-angle of incidence between the Standby Heat Loss-7.-Heat lost through stor- sun's ray and a line normal to the surface. age tank and piping walls. (Rate of heat loss differs from standing still and when moving.) Trickle Type CollectoeA collector in which .the heat transfer fluid.flows in open channels Storage Mass(See Heat Storage.). on the absorber. Sun Path Diagram (Solar Window)A circu- True SouthSouth with reference, to the lar projection of the sky yault, similar io a stars, not to a compass. Opposite to the Pole map, that can be used to deterrnjpe solar Star, which lies to the true north df Earth. positions and to calculate shadin Tube-in-Plate AbsorberA metal absorber Sun TemperingDesigning a house to de- plate in which the heat-transfer fluid flows rive some of its heat directly from the sun through passages formed in the plate itself: (though not necessarily enough Pe qualify as a solar house). - Tube Type CollectorA collector in which ,the heat transfer liquid flows through metal

Temperature ZonesAreas controlled to .tubes that are fastened to the absorber plate maintain different temperatures withina by solder, clamps, or other means. (See Col- house. lector%)' o

7 5 71 UltravioletRadrationXectromagnetiC. WattThe unit of rate at which work is done radiation with wavelengths slightly shorter in an electrical circuit, equal to thejate than visible light. flow (amperes) Multiplied by the pressure 61 that-flow-(vott0._ Unglazed CollectorA collector without a cover plate. WeatherstrippingNairoW or jamb-width sections of thin metal or other rnaterial to U Value (Coefficient of heat transfer)--The preventinfiltration ofair and moisture number of BTU's that flow through one square around windows and doors. foot orrobt-Walt-orfloor in one hour, when there is a 1F difference in temperature between the inside and outside pair, under, steady state conditions. The U value is the GLOSSARY REFERENCES reciprocal of the "resistance or F-factor. Homeowners Guide to Solar HeatingI. I Vapor BarrierA component of construction ' LinePu,bashing Company which is impervious to the flow of moisture Menlo Park, CA and air and is used to prevent condensation in walls and other locations of insulation. Installation Guidelines for Solar pH W Systems U.S. Department of Housincrand Urban - VoltThe unit of pressure in an electric Development circuit. Second Editidn Water WatlAn interior wall of water-filled Producing Your Own Power containers constituting a one-step heating Carol Stoner stem which combines collection and Rodale Press storage. Ernmaus, PA

72 APOENDIX B-SOLAR REFERENCES

n 1. Solar Greenhous , 'Construction and Photographs on greenhouSe design and construction, and a few papers address pro- The Solar Greenhouse Book .duction methods, James McCullagh Rodale Preas -33t:-MitibrStreet Emmaus, PA 18049 $8.95 328 pages Biological Management of Passive Solar The. most compratiensive book'to "date on the Greenhouses design, construction, and management of National Center for Appropriate TechnOlogy various solar greenhouses throughout 'the. P.O. Box 3838 ---bountry, Butte_j4ontana 59701 An excellent vnotated bibliography on sOlar The Food and Heat Producing Solar greenhouse production methods, biological 0, Greenhouse , nest control, and horticulture. Also Includes Rich Fisher and Bill Yanda a unique resource list oylndividuals and John Muir Publications groups experieRced in construction and P.O. Box 813-R management of passive solar greenhouses,- Santa Fe, NM 87501 $9,50 181 pages_ and a list of companies which sell beneficial The claseic beginner's book on solar green- insects. houses, with good advice on plant management, space utilization, and constructiOn de- The Survival Greenhouse

tails, . James B. DeKorne Walden Foundation The Complete Greenhouse Book Building P.O. Box 5 / ( and Using Greenhouses From Cold El Rho, NM187530 $7.50 165 pages Frames to Solar Structures The buthbr Oscribes two yeiirs experience Peter Clugg and Derry Watkins growing,vegetables, rabbits, anb fish In'en Garden Way Publishing underground solar greenhouse. The, book Charlotte, V'T 05445 $8.95 285 pages contains one of the few honest assessments Provides criteria for design of all .types of of hydroponic systems, both chemical and greenhouses, with emphasis on solar sittuc organic. tures. Excellent seallions onplant diseases, soils, and growing conditioris, with many fine How to Grow Morg4 Vegetables Tha4 Yoe' drawings and photographs. Even Thought Possible on Less Land Than You Can Imagine The Passive Solar Energy Book John Jeavons Edward Mazria Ectlogy A.ction of The Midpeninsula Rodale Press 2225 El Camino Road 33 E. Minor Street Palo Alto, CA 94306 $4.00 , 81. lieges Emmaus, PA 18049 A step-by-step descriptron of the French In- An excellent resource of passive solar funda- tensive method of gardening which can ap- mentals. including step-by-step design preciably.increase qop. yields.. Espeolpily apt methods for solar greenhouses. Used as a propriate for greenhouses where Vowing textbook for many solar coursesr spaces.limtéd. , . Proceedings-of the Conference on Energy The Secret Life of Plahis Conserving, Solar HeatedGreenhouses, Peter Tompkinsand Christopher Bird 11 1977 Avop Books. 1973 John Hayes and Drew Gillet, Eds. 959 Eighth Avenue Marlboro College New York. NY 10019 $1,95 418 pages Marlboro, VT 05344 $9.00 282 pages .14as very little to do with gleenhtses but is A survey of innovative solar greenhouse pro- an astonishing account of the ph sical, emo- lects by greenhouse owners, university re- tional. and spiritual relations between plants searchers. and representatives of community and people. Highly recOmmended for anyone 0110 groups. Most papers include illustrations who grows plants. - Horticultura-1 Maneimant ol Solar. *Burgess Seed & Plant Co. GthenhoOses the Northeast Box 2000 The MEMPHREMAGOG Group Galesburg, MI 49053 P O. Box 456 Newport,VT 05855 .4 - *Burpee,W. AtleaCo. 300 Park Ave. This manual was written to share the4succes- Warminster, PA 18974 ses and failures that many'solar greenhouse 4. owners have had grbwing food crops. Pro- Comestock, Ferre & Co. vides basic 'information on how best to use 263 Main St these structuresto,produce food. .Wethersfield, CT 06109

Organic Gardening Under thass DeGiorgi Co, Inc. G roe andNaty Abraham Oouncil Bluffs, IA 51501 Rdplé RresS 33 .Minor Street Demonchaux Co., Inc. 308 pages Emmaus, PA.18049 - $8.95 .?25 Jackson Though written for the hobbyist who is' using Topeka, K966603 a conventional-, structure, most of the infor- mationis also kapplicable" to solar green- Ferndale Gardens house grow! g.or a range and depth of cov- 702 Nursery Lane erage, thiS b ok on organic gardening is harii Fairbault, MN*55021 to beat. Fruitland Nursery SOmrnary &Cool Weather Crops Tested -307 Whitley Dr. 19'79-80 Foi Solar Structures Fruitland, ID 83619

Organic Gardening and Farming pesearch N -Center -* Grace's Gardens RD 1 Autumn Lane Kutztown,-PA 19530 Hackettstown, NJ 07840 .This new report presents the results 'of extensive testing of vegetables, herbs, and.- *Gurney Seeds&Nurser/Co. flowers in Solar greenhouses. Includes pest 2nd & Capitol Sts.. nianagesnent, harvesting techniques, and. Yankton, SD 57078 recipes. Henri/'Field Seed).Nursery Co . Shehandoah, IA 51602 ' 3s,,SeedSources *Herbst Brothers Seédsman, 100 N. Main St. (_ 'BULBS Brewster, NY 10.5G9 ° Van Bourgondien 245 Farmingdale Rd. Japonica Nurser'y P.O. Box A ,P.O. Box 236 Oabyl'on, NY 11702 Larchmont, VY 10538 / HERBS nny's.Selected Seeds Meadowtrook Herb Garden AliOn, ME-049'10 Wyoming, RI 02898 .. 'JoseOh H rris Co., Inc. WeH Sweep Herb Farm Morelon Fa 317 Mt. Bethel Rd.. .Rochester, NY 14624 Port Murray, NJ 07865' Kitazawa Seed Co. ORIENTAL VEGETABLES 356 W. Taylor St. A World Seed Service ..., San JOse, CA 95110, c/o J.L.udson SeRdsman'41 P.O. Bo 1058 A LeJardin du Go.urrnet ' Redwo d City, CA 94064 W. Danville, VT 05873 -Nichdts Garden Nursery 4.7 Movable Insulation and Shading Methods 1190 N. Pacific Highway Albany, OR 97321 Solar Control and Shading Devices Olgyay and Olgiyay 'Park, Geo. W. Co., Inc. Princeton Univeisity Press, 1957 Greenwood, SC 29646 Princeton, NJ

Radhey Shian &Co. Design withClimate SeedGrOwers &Merchant Victor Olgyay Kutabkhana Sabiimandi , Princeton, University Press, 1963 . Bareilly, India Princeton, NJ Redwood CitrSeed Co. These two booki are classics in the field of P.O. Box 361 passive solar design, even though They ware Redwood City, CA 94064 written before energy became an issue in butlding design. They contain rnorOaluable Richter, Otto & Son,' information on solar control which can never Goodwoodapntario go out of date. 'Canada LO 10A Selecting and GroWing Shade Trees Sepdway, Inc. U.S. Department of Agriculture Hall, NY 14463 Washington, D.C.

ShuMway, R. H. Co'. Thermal Shutters and SOades RockfordIL 61101 WiIliamShurcliff. Brick House Publishing Stokes Seects, Inc. 3 Street ,BoX 548 Andover,MA 01810 $12.95 238 Pagei Buffalo, NY 14624 Movable Insulation Sutton Seectt K. Langdon Reading, EAgland Rodale Press Ernmaus, PA ThoMpson & Morgan, Inc. The most complete books to date oh home- P.O. Box 24. made and cortimercially availabre? insulating 401 Kennedy Blvd.. Irwdevicealor windows and greenhouses. Sornerdale, NJ 08083 ...Jsang & Ma International 1556 Laurel St. San.-Carlos, CA 921070

Cinroloct Farm sP ore °The above seed sources are reprinted from: Organic Gardening Research Center RD:1 vs Kutztown, !A 19539 , *Offer soil test kitS,

o * APPENDIX C SOLAR AIR41EATERREFERENCES

Solar Air Heater Manual Solar Survey Joel Davidson National Cso. ter for Appropriate Techpology Office of Human Concern, Inc. P.O. Box 31.38 40 P.O. Box 756 Butte, MT 597,01 ,Rogers, AR 72756 aluatiOn of the OHC Solar Air Heater Simple Solar Air Heaters Ru s Garton and Steve Metcalf Ron Hughes Dep rtmenf of Mwhanical-Engineering, New Life Farm, Inc. University Of Arkansas Drury, MO 65638 Fayetteville, AR 72701

Project Focus #3 Low Cost Solar CollectOr Solar 9ertical Wall Collector Bill North Small Farm Energy Project San'Luis Valley Solar Enargj, Association P.O. Box 736 P.p. Box 1284 Hartinglon, NB 68739 AlamSsa CO 81101 ,

Solar Air Heater Manual "Walls of Warm Air"

Jim Free Joe Carter 11 Crowley's Ridge Developfnent Cwcil, Inc. New Shelter Magazine, May/June 1980 Jonesborb, AR

Air Flow Tests of Solar Air Heater Dr. Thomas Rokeby,'RfE, Agricultural Engineering Department Univeroity of Arkansas , Fayetfeville, Arkansas 72701

r` APOENDIXD-SOLAR WATER HEATER REFERENCES

"Heating Water in a Breadbox" Hand Made Hot Water Systems Allen Van Fleet Srt Sussisman and Richard Fraizer Alternative Sources of Energy. April 1977 Garcia River Press P.O. Box 527 "Sun on Tap" ' Point Arena, CA 95468 Frederic Langa New Shelter; May/June 1981 Sunspots Steve Baer "Breadbox Detgns" Zomeworks Corp. Jeff Reiss and avid Ba' P.O. Box 712 , Alternative Sources of Alburquerque,`NM 87103

Solar Hot Water Build Your Own Solar Water Heater Nicholas Brown Steve Campbell Arkansas Energy Office Garden War.Publishing Charlotte, VT 05445 Solar Energy and Its Use for Heating Water F,A. Brooks , U.C. Berkeley. Agricbltural Experimental Station Bulletin 602

.77 E 1 SOLAR PERiODICALS

Solar Living & Greenhouse Digest New Shelter P.O. Box 10010 Rods le Press Phoenix, AZ 86016 SID/bi-monthly 33 E. Minor Street Emmaus, PA 18049 $9, monthly Solar Living & Greenhouse Digest P.O. Box 10010 Mother Earth News Phoenix, AZ 86016 $10/bi-monthly P.O. Box 70 Hendersonville, NC 27891." $15.00 Monthly Solar'. Age P.O. Box 4934 Solar UtilizatioR News Mancheater, OH 03108 $20/birrionthly P.O. Box 3100 Estes Park; CO 80517 Alternative Sourdes of Energy Milaca, MN 56363 $15/bi-monthly

.4111P,

a 78 APPENDIX F SOLAR INFPRMATION S URCES

Arkansas Energy Office The Nation olar Heating androoling 1 Capitol Mall Information Center Little Rock, AR 72201 P.O. Box 1607 (800) 482-1122 or (501) 371-1370 Rockville, MD 20850 (800) 523-2929 Southern Solar Energy Center 61 Perimeter Park The National Center for Appropriate Atlanta, GA 30341 Technology P.O. Box 3838 Solar Energy Research Institute - SERI Butte, MT 59701 Information Systems Division (406) 404-4,572 1617 Cole Boulevard Golden, CO 80401

79 APPENDIX G SOLAR RADIATION DATA

512 510

Mean Annual Total Solar -Radiation (Thousands of Btu's per Ft2)

80 7,4101114670 111011406g5 January P I114h6WiNrt4Tn5 01,Vo

, 5 ,EVALE

7 'WildtriorV

tirpe.,44016, FebruarY plikillW190855 Ir-4411ffillaato30 Ibk lq

81' Mean Daily Solar Radiation(BTU/1t2)

April

1540 1555

82 (-)(/ Mean Daily Solar Radiation (BTU/ft2).

May

97-5 1935

'June Mean Daily Solar Radiation (STU/ft2) ,

1870 1850 1830

August

84 !lean Daily Solar Radiation(BTU/ft2)

1115

1095

1115

1130 s' Mem) Daily Solar Radiation (BTU/ft2)

Novern6er

86 EVALUATION OF

.SOLAR RADIATION MAPS The general trend of the solar radiation inversion is that cloud cover is greater in the maps shows the effect of latitude on the values. southern part of the state, brought about by mois- The winter months (January, FebrUary, De- ture from the Gulf of Mexico. Information from the cember) as well as the spring and fall months National Weather Service for the years 1960 (March, April, May, and \September, October, through 1969 do, in fact, show slightly higher November) generally show the radiation values percentages of cloud cower in the summer increasing in a'southerly direction. The month of monthsforJackson,'fiississippi,and April is an exception. The contour lines for April Shreveport, Louisiana,. than for Little RocR, Ar- show only a ao Btosnt2 day variation across the kansas, '11 ulsa, Oklahoma, and Springfield, Mis- state. The contour lines fai. April tend to show a souri. . north-south pattern with the highest values being Another reason for the solar radiation inver- in the eastern part of the state, along the Missis- sion is ine position of the earth in relation to the sippi River. sun during the summer months. (See Figure 6.) Contrary le the winter, spring, and fall The declitiation angle of the earth reaches its months, the summer months (June, July; Au- maximum positive valt.le of 23.45° on June 21, 14 gust) show the solarradiation values increasing the summer solstice. At this time, the North Pole with increasing latitude. In other words, there is cah receive sunshine 24 hours a day, but the more radiation in -the northeth part of *le statd radiation intensity on dear daysIs weak because than in the southern part. One cause, for this of the steep angle of the sun's rays at that point.

Autumal Equinox 6 = 0 FIG. 6, MOTION OF THE EARTH Septembers?) AROUNd THE,SUN 23.45°

Winter Solstice, Yernal quinox Summer Solstice 6 -23.450 6 d' 6 +23.45° Decembei- 21 March 2 June 21

On the other hand, the latitude near th4Tropic of I with radiation values decreasing towards each Cancer.can receive only about 1? hours of sun- I extreme. This peak clear-davadiation value.oc- shine each day, but the radiation on clear days is curs north of the state of Arkansas during the stronger because the sun's rays there are per- summer solstice. Therefore, during:the sumMer pendicular to the earth's surface and have less months, the northern portions of the itate would atmosphere to pass through. The two factors be expected to re§2)ive more solargradiation, angle of the sun and length of daily sunshine tonO based solely on clear-day predicted values. to balance each other at the two extremes, so Generally speaking, the variation in the peak their predicted radiation tOtalslor. clear days in radiation on clear days and the cloud patterriover summer are about equal. , the state combine to account for the inverrsion The highest clear-day radiation values in effect during Ihe sUrnmer months with the sbuth- summer in the°northern hemisphere occut ernmost portion of the state receiving slightly less tween the North Pole and ttle Tropic of Cancer, solar radiation,

87 96, 4. TILT FACTORS tions and to minimize the effect of latitude on the The solar radiation maps can be used tofind tilt factors, the state has been sectioned into the the total and beam solgt radiation ohsurfaCes other than horizontal by using tilt factors. jilt three regions indicated in Figure 7. /. Tilt factors for each of the three regione haVe factors are simply coefficients which enable-us to been calculated for south-facing tilted and verti- predict solar radiation levels on a surf ade of any cal surfaces, and for past, west, and norih, The angle or orientation once the'ho-rizontal radiation tilt factor used to find the total solar radiation is is known: 1113.. Tilt factors for eachregion are given on Equations for tilt fpctors are dependent'upon latitude, so their value generally will' increase pages 89 - 91,'followed by step by step methods fiorn north to south. In order to simplify calcula- 'for using the tilt factOrs, along with example calculations.

Tilt Factor Regions

88 . TILTFACii3ORSFOR IWGION 1

VERTICAL SURFACES

Southeast and Southwest East and West North RT if Tr Re T ifB T

, JAN 1.11 1.49 .72 .74`. .33

FEB (-.-.95 1.14 .70 59 .31

MAR .77 81 i.67 53 .31

APR .62 .54 , .644 .58 .314

MAY .53 .38 .63 .54 .33

JUII .47 .30 '.62 .53 .33

JUL .49 .53 .32 ' AUG .57 .46 .64 .06 .30

SEPT .70 - 58 .66 .61 .31

- OCT .99 :69 .66 .30

NOV 1.05 .71 .72 .33

DEC 1.16 1.62 .73 .33

TILTED SOUTH-FfiCING SURFACES

o TILT 20° 50 65° VERTICAL

, ...... 4...... MONTH RT RB RT R R .R RT RB RT RB B T B ,

. , , JAN 1.31 1.62 1.46 1.95 1.542.16 154 2.22 136 1.98

FEB 1.21 1..40. ' 130 1.59 132 1.68 1.28 1.65 1.06 1.35 i MAR 1.11 1,22 1.14 1.29 r 1.11 1.28 1.02 1.17 .78 .83

APR 1.03 1.07 1.00 1.93 .92 .93 .80 .77 .54 .40

MAY .98 .97 .91 .88 .81 .73 .67 55 .42 .19

JUN .95 93' .87 .811. .75 .65 .61 .46 .36 .12

JUL .96 .94 .88 .84 .77 .68 .63 49 37 .14

AUG 1.01 1.02 .96 .96 .86 .83 .73 .66 .47 .29

SEP 1.08 1.16 1.07 1.17 1.02 1.11 .92 .98 .66 .62 , OCT . 1.17 1.33 125 1.48 125 1.52 1.19. 1.46 .971.15

NOV 1.27 1.55 141 1.84 1.47 2.01 145 2.04 126 1.78 .,_. DEC 1.33 1.69 1.51 2.08 1.602.32 1.61 2.41 1.442,19

89 97 TILT FACTORS FOR REGION 2

VERTICAL SURFACES

.. N'brth MONTH 'Southeast and Southwest East and West RT Ri. RS 147. 138

1 JAN 1.07 , 1.43 .71 .72 ' .33

.30 F E B .94 1.09 .70 .67 , . / MAR .75 .78" '..87 62 .31

.31 APR .61 52 54 .5 . , MAY, 61 .36 Z2 .54 .32

.33 JUN .46 .29 .61 H.. .52

JUL .48- 31 .62 .53 .33

, .30 AUG .66 .44 .63 .56 4 . .31 SEPT .69 .66 .65 50

.69 .65 .29 OCT , .07 .96

NOV 1.03 1.31 .71 .71 .32

1 .33 DEC 1 12 1.55 .72 .74 ei .1

TILTED.SOUTH-FACING SURFACES

0. VERTICAL TILT 20° 7.35? . '65° I

RT, R MONTH RT Fir, RT .RB RI. RB B nG. ' Ill' R 8

JAN 1.29 1 5,8 1 1.43 -://1 .90 1.502.09 1.49 2.13 130 1.89 .. 1.4* FEB 1.22 1.40 1.31 158 1.331,46. ;14, 1-.63 1.07133

MAR /4 1.11 121 1 .13 127 . . 1 .09 1:25 1.00 ,1:14 .78. .79

.37 APR 153 1.06 1..99 , 1.02 .91 .,s, .79 - .75 .53 ... MAY .96''.97 .90 .87 .79 .72 ,, .66 53 .40 .17

.60 .44 .35 .10 JUN .94 .9? .86 .80 .74° .64 . 47/ JUL .95;.94. .88 .83 .76 .67 .62 ) .37 .13 .: 'AUG 1.00 151 .95 .94 . .85 .81 .72 .64 .48 .27 A SEPT 1.07 1.1,4 1.08 - 1.15 1.01 1.09 .90 .95 .65 .59

. -,

-: . OCT ,,1 ie.. 132 .124 '. 1,45 1.24-1 49 - 1.18. 1.42 .95 1..10

1 45 1.94. 1.43 1 .96 ' 124130' NOV 0 4127 1.62. 1 AO: . 1.79

DEC 132 155 . l'AS 2.07 1.58.2.24 . 1 .67 231 1.392.09

90 TILT FACTORS FOR REGION 3

VERTICAL SURFACES

MONTH Southeast and Southwest East and West North Re RT Re RT rT JAN 1.08 1.37 .71 .71 .32 r.

F E .90 1.05 . .69 .66 .31 ,

MAR .714 .75 .66 .61 .30

APR BO .50 .84 .56 .31

MAY .so .34 .62 '.53 .32

JUN .46 .27 .81 .52 .34

JU L , AUG )55 .42 .63 .55 .31

1 SEPT 68 .84 .85 .59 .30

OCT .84 .92 .68 .64 .30

NOV 1.01, 1.26 .70 .69 .32

1 DEC 1.08 1.48 .71 .72 .34

TILTED SOUTH-FACING SURFACES

- TILT 20° , 35 9 50° 85° 90°

MONTH RT RT .118 RT FIB RT Rs RT RB R 8 , JAN .1.29 1.55 1.43 1.85 1.492.02 1.48 2.05 1.291.80

'tt3 1.20 1.38 1.28. 1.55 1.29 1.62 1.24 1.58 1.02 1.28 I MAR 1.10 1.20 1.12 125 1,.08 1 22 .99 1.11 .74 .78

0 APR 1.02 1.05 .98 1.01 .90 .902, , .78 .73 .52 .35 v. 4 MAY .97 .96 ,.89 .88 .78 .70 .65 .51 .39 .16 l

JUN /24 .91 / .85 .79 .74 .62 .59 .43 .35 .09

JULY .95 .93 .87 81 .76 '.85 .61 f .46 .38 .11

AUG 1.00 1.00 .94 .93 .84 .80 .71 .62 .45 .25,

SEPT 1.07 1.13 1158 1.14 1.00 1.07 .89 .93 .83 .58

OCT 1'.17 120 1.22 1 A2 1,22 1 A5 1.15 1.38 .92 1.05

NOV . 1.26 1.50 1.38 1.75 1.431.89 1.46 1.90 1.201.63

DEC 1.29 '1 .62 1.44 1.96 1.522.17 1.51 222 1.331.99

9199 MEAN DAILY TOTAL SOLAR RADIATION FOR TILTED AND vgRTICAL, SURFACES, (Trrs) Step 1Find the mean daily total horizontal Step 1-LLook at the mean daily total horizontal solar radiation, iTH, for the month and solar radiation map for January on location of interest from the solar radia- page 81. For Little Rock,

, tion maps. Step 2.--Look at Figure 7 on page 88 to deter- 1TH=740 BTUM2day mine what region of the state your location is in. , Step 2Looking at Figi.le 7 on page 88, we Step 3Look in Tilt Factor tables, pages 89 to see that Little Rock is in Region 2. 91, for the appropriate tilt factor, RT. Stela 3From Tilt Factor Table on page 90, for the month of January and a tilt of SiMply multiply the tilt factor (PT) by the 35°, FIT is found to be 1.43. Therefore, total horizontal radiation (TTH) to get the ITTs = 740 x 1.43 = 1060 BTUM2 answer: day. Answer: TTTS = H T To find monthly average value, multiply Mr. Jones can expect an average of 1060 TT-rs by the number of days in the BTUM2 day incident on his fjat-plate collectors month of interest. during the month of Janudy. For the entire month, he would expect: Example One (1060 x 31 days = 32,860 BTUM2 Mr. Jones of Little Rock is thinking about The transparent covers (glazings) on the col- installing flat-plate collectors on his roof for lector will further decrease the value of solar water-heating purposes. His roof, faces due radiation and must be taken into account to de- south w,ith a tilt of 35° from the horizontal. Find the termine the solar energy actually received by the amount of total 'solar radiation falling,on his flat- collector (See Example 3). plate collectors for a day in Januaryi.'

MEAN DAILY BEAM SOLAR RADIATION FOR TILTED AND VERTICAL SURFACES

(1BTS) Step 1Find the mean daily total horizontal solark Step 4Calculate the diffuse (1DIF) to total radiation, TTH, for'the month and loca- (ITH) split by the follOwing equation: tion of interest from the solar radiation maps on pages 81 - 86. DIF= 1 - 1.096AT Step 2Find the mean daily ext,raterrestrial TTH solar radiation on a horizontal surface, Step 5Calculate the mean daily beam radia- TEXT from Table 2: tion on a horizontal surface, 1B, by the following equation:

Step 3Calculate RT by the followingequation:' TDIF 17 -1TH TB = (1-TTH ) x TTH nT =T ,EXT

(Jo 92 TABLE 2 MONTHLY AVERAGED DAILY EXTRATERRESTRIAL SOLAR RADIATION MONTH, Tocr (BTUM2day)

REGION 1 -\ REGION 2 REGION 3

JAN 1540 1607, 1674

FEB 2016 2039 2100

MAR 2551 2598 2643

APR 3121 . 3146 3168

MAV 3488 34Q2 3495

JUN 3637 3630 3621

JUL 3564 3561 3557

AUG 3270 3284 3297

SEPT 2768 2806 2841

OCT 2180 2235 2290

NOV 16B8 1723 1788

DEC 1407 1475 1544 Step 6Loon Tilt Factor Tables, pages 89, 90 Step 5The split is calculated. as follows: and 91, for appropriate beam tilt factor, TDIF AB. The Mean daily beam component _ = 1 -1.096 0.460 = 0.495 ot radiation on the tilted surface:1E1-m, 1TH is calculated as follows: Step 6The mean daily beam comloonent is 'BTS 'B X TIB calculated as follows: Example Two B = (1 - 0.495) x 740 = 375 BTUM2 day Suppose Mr. Jones would now like .to know the average amount of beam solar radiation that will be incident on Siep 7Mr. Jones' roof was south-facing with a his flat-plate collectors foT a day in 350 tilt of .From Re_gion 2 Tilt Factor January. Table on page 90, AB is foand to be Solution 1.90. Therefore, Step 1The mean daily total 'horizontal solar _ radiation contour map for January is on IBTB = '375 x 1.90 = 710 BTU/ft2 'page 81. Looking at the map for Little Rock TTH = 740 (BTU/ft2day, Answer:

Step 2Looking at Figure 7, we find that Little Mr: Jones can expect an average of 710 Rock is in Region 2. ,BTU/ft2day of beam radiation on his flat-plate collectors during the month of January. As in Step 3From Table 2 and the month of II. Example 1, this amount is subject to a reduction January, TEXT is found to be 1,607 due to glazings used on the collector (See Btu/ft2day Example 3). Step 4RT is calculated as follows: 74° 460 ' 1 ,607 93 -SOLAR RADIATION 'TRANSMITTED THROUGH GLAZINGS A glazing is any transparent material, such Figure 8 depicts the solar energy flow as glassAberglass, or pladtic, whichalloWs light through a ,double glazed surface. This surface ibpass through. In many solar and architectural can be considered a window, asolar collector appliçations, more than one layer of glazing is cover, a greenhouse, a slidingglass door, or any used t educe heat losses. other transparent surface.

I -T2 DN

FIG. 8, TRANSFER OF ENERGY THROUGH GLAZED SURFACES REF TRANS

-- The transmissivity of the glazing, or, is a Trrs = 1.06 X 995 = 1,055 BTU/ft2day measure of how much radiation (or light)is transferred through each layer of glazing. The energy Step 4-L-From Table 3 9n page 940erfcir each 'transmitted, citrans,,for the sketch in Figure 8 can wirttslow pane ié 0.85. Therefore be apProximated by the followingOuation:, qtfans = 1,055 x (0;85) x (0.85) = 76OBTUM2- qtrans = TITS ('a) X ) Example 3

Mr. Smith of Fayetteville,Arkansas,' has a Answer: vertical, south-facing, double-paned, tempered Mr. Smith can expect an average of 760 glass window in his den.' He would like to know BTU/ft2day of solar energy to be transmitted the amount of solar radiation that is transmitted through the window that coUld be absorbed in his through the window into his den for an average' den space for an average day in the month of day in the month of February. February. If the window area is 10 ft2 then 760 x Solution 10 = 7,600 BTU. would be transmitted through the window each day. The average radiation for 'Step 1Following the method presented in the' entire month of February would be 7.600 x Example 1, from the February solar 28 (days) = 212,800 BTU. radiation map on page 81, the total horizontal radiation TTH, is about 996 BTU/ft2day in Febthary. Step 2From Figure 7 on page 88, Fa9etteville TABLE 3 TRANSMISSIVITY OF GLAZINGS is in Region 1. .92 Step 3=-From Region 1Tilt Factor Table on 'LOW-IRON GLASS .91 ACRYLICS TEMPERED GLASS .85 page 89 for vertical south-' POLYETMELYNE .82 facing surfaces in February, AT is WINDOW GLASS .90 CLEAR VINYL .91 found to be 1.06. Therefore, F IBERGLASS REINFORCED POLYESTER TEDLAR,(2VF FILM) .93 TUS=-XTTH PO LYCAR BONATES .90

94 Jo BEAM AND TOTAL SOLARRADIATION TABLES'

the ,previous two sections discussed for the state can be considered as 35 degrees, methods on how to carry out beam and total solar tilts of 20, 35 and 50 degrees were shown: For radiation calculations using the tilt factors on comparative purposes, the radiation on horizon- pages 89 through 91. This section contains a tal and vertical south-facing surfaces were also complete set of tabulated beam and total solar shown. The area under the curve indicates the radiation values for a city, in each of the three annUal amount of solar ,radiation. regions, of the state. The cities chosen were Another graph, for each city shows the ef- Fayetteville for Region 1, Little Rock for Region fects of orientation for vertical surfaces (Figures 2, and Texarkana for. Region 3. The resufts are 10, 12, and 14). Radiation values are given for presented in the tables 4 through 9 that follow on vertical surfaces facing east, west, southeast, pages 96 through 101. southwest, north and south. Also presented for each city is a graph show-/ The amount of total horizontal solar radia- ing the effects of tilt for south-facing surfaces tion falling on other locations within the State can (See Figures 9, 11, and 13). A rule- of thumb for be found from the contour maps.. The results in maximizing the amount of solar radiation col- each region will vary, depending on the monthly lected on a year-round basis is to tilt surfaces the average, but will be dose to the values shown in latitude,-± 15 aegrees. Since the average latitude Tables 4 thrOugh 9 and in Figures 9 through 14.4

1 03 .95 TABLE 4 SOLAR RADIATION ON SOUTI4FACING TILTEDSURFACES FAYErrEVILLE (REG(ON 1)

350 0 TILT HORIZONTAL 20° 50 65° VERTICAL

MONTH , TOTAL BEAM TOTAL BEAM TOTAL BEAM TOTAL BEAM TOTAL BE* TOTAL BEAM.

.. JAN 720 370 940 595 1055 720 1110 795 1110 820 975 730

FEB 995 540 1205 755 1290 860 1315 905 1270 885 1055 730 -N.. MAR 1275 700 1420 855 1450 905 1410 895 1305 ' 820 995 580

APR 1625 925 1675 990 1620 960 1495 865 1305 715 880 370

MAY 1900 1135 1855 1100 1725 995 1530 835 1275 620 790 215

JUN 2105 1335 1995 1235 1820 1085 1575 870 1280 610 755 155

JUL 2115 1375 2025 1295 1860 1150 1620 940 1325 ( 675 . 780 200

AUG 1875 1180 1085 1200 1795 1125 1620. 980 1375 775 875 340

SEPT 1395 770 . 1500 885 1495 905' 1420 860 1280 755 925. 475 e OCT 1120 630 1320 840 1400 930 1400 960 1335 925 1080 725

Nov . 780 400 995 625 1100 740 1145 805 1135 EIV 985 1 715 , DEC 635 315 845 530 955 655 1015 730 1025 760 "--...415' 690

FIG. 9. EFFECT OF TILT ON SOUTH-FACING SURFACES 2500

0°

. .. ******* "1... ..0'.0 . ... 350 ...... :: ....r'S ..'7°' . % 500 A...... 1 ? '0% 4.1t)...... v 4..... % '/* 1500 i...... 4 ' ii 41% t. 4.4 944..

Pr "\ '4. .c.s.4 WOO 411. ui o°

4 500

04 I' I I I Jan.Feb.Mar.Apr. May June July Aug. Sept. Oct. Nov. Dec.

96 40(1 TABLE 5 SOLAR RADIATION ON VERTICAL SURFACES FAYETTEVILLE (REGION 1)

SOUTHEAST AND SOUTHWEST EAST AND WEST NORTH MONTH TOTAL BEAM TOTAL BEAM TOTAL JAN 795 550 520 275 235 V FEB 945 t 526 700 375 305' MAR 900 565 855 440 395

535 505 APR 1015 599 1045

MAY 1000 425, 1190 616 620

JUN 995 400 1300, 705 700

JUL 1035 455 1315. 735 870

AUG 1075 . 540 , 1195 NO 555

SEPT 980 525 920 485 430

OCT 9110 825 775 415 340

NOV 820 550 560 290 255

DEC 735 510 485 240 215

FIG. 10. EFFECT OF ORIENTATION ON VERTICAL SURFACES

Jan.Feb. Mar.,Apr. May June July Aug. Sept. Oct. Nov. Dec.

971 05 TABLE 6 SOLAR RADIATION ON SOUTH-FACING TILTED SURFACES LITTLE ROCK (REGI9N 2)

350 TILT HOR IZONTA L 20° 50° VER TICAL

MONTH TOTAL BEAM TOTAL BEAM TOTAL, BEAM TOTAL BEAM TOTAL 'BEAM TOTAL BEAM JAN 745 380 980 600 1065 720 1120 790 1110 805 970 715

, I

1375 940, 1400 985 1355 965 . 1125 . 790 FEB 1050 \. M 1275 825 MAR 1300 715 1440 685 1465 910 1420 890 1305 815 990 595 .. APR 1630 925 1670 .980 1615 945 1485 845 1290 695 866 345

MAY 1945 1185 1890 1145 1755 1030 1545 855 1280 630 780 205 . JUN 2110 1345 11195 1240 1810 1075 1560 855 1260 ,t 65 730 140

, JUL: 2036 1275 1945 1195 1780 1050 , 1550 850 1265 605 745 166

AUG 1860 1155 1860 1165 1765 1090 1585 940 1346 735 845 310

SEM 1420 790 1520 900 1510 910 1130 860 1285 750 920 466

OCT 1185 690 1395 905 1470 .1000 1475 1025 1400 980 1125 7t0

'i' NOV 835 445 1060 675 1165 795 1215 865 1200 870 ' .1035 756

DEC 670 336 880 550 990 675 1050 750 1050 770 930 895 FIG. 11. gFFECT OF TILTaN SOUTH-FACING SURFACES 2500

2000

1500

1000

500

Jan.Feb.Mar. Apr. May June. July Aug. Sept. Oct. Nov. Dec.

1 06 98 TABLE 7 SOLAR RADIATION ON VERTICAL SURFAC6 LITTLE ROCK (REGION 2)

MONTH Southean and Southwest Ent and West North

TOTAL BEAM TOTAL BEAM. . TOTAL .1 # JAN 795 540 530 275 4, 246

FEB 980 860 730 400, , )` 3113

MAR aso 565 ses 4'40 400 > APR 1000 485 1045 530 510

MAY 1000/ 430 1210 640 025 , . jUN eso 385 1295 700 700 C)

675 65 JU L 985 400 ,1255

555 AUG 1050 . 510 1180 640 7

SEPT seo 520 930 470 435

OCT 1025 660 815 445 360

NOV 880 686 599 ' 315 i 286 . DEC 750 516 .480 245 225 e

FIG: 12. EFFECT OF ORIENTATION ON VERTICAL SURFACES 2500

2000 0 4 a 0 'so° 0 ca

1000

500

ge.

Jan. Feb. Mar.Apr.May June July Aug. Sept.Oct. Nov. Dec.

107 99 C TABLE 14 SOLAR RADIATION ONSOUTH-FACING TILTEkSURFACES. TEXARKANA (REGION 3)

TI LT HOR IZONTA L 00. de VERT ICA L

MONTH. TOTA L BEAM TOTA L, BEAM TOTAL BEAM TOTAL BEAM . TOTAL' BEAM TOTAL BEAM . JAN 810 430 1040, 670 . 1155 -, 795 1210 870 1200 . 880 1045 775

FEB 11040. - 565 1245 775 1325 875 '1345 915 1290 890 1065 720 .

. MAR 1355 760 1495 915 3520 955 1465 9-30 1345,. 845 1010 575

APR 1 635 925 1670 970' 41605 930 1470 830 1270 670 845 . 325

MAY. 1980 1 230 1915 1175 1770 1050 1555 8 65 1280 630 765 190

JUN 1, 2025 1240, 1905 113.5 1730 980 1490 775 1200 530 705 110

JUL 1975 1200 1680 1 120 1720 980 1490 785 1215 550 720 135

AUG 1820 '1100 1810 1104-, 1710 1025 1535 880 1295 680 815 , 270

SEPT 1470 835 1570 940 1555 , 0 1465 890 1310. .775 930 465

OCT 1205 695 1405 90.5 1475 980 1470 1010 1309 955 1110 730 , _ NOV 875 470 11.00 700 1205 .820 1250 885 1230 890 1055 765

, DEC 690 340 895 550 995 660 1045 730 1040. 750 915 670

FIG. 13. EFFECT OF TILT ON SOUTH-FACING SURFACES 2500

2000

rz.

1500 cr cc 05 loot) . 1 LIS

cc 4. 500

?.3

Jan.Feb. a .A r.May June July Aug. Sept. Oct Nov. Dec. TABLE 9 SOLALLRADIATION ON VERTICAL SURFACES TE*RKANA (REGION 3)

. East and West 'North Southeast and Southwest ,. TOTAL MONTH TOTAL BEAM TOTAL BEAM . . (160 .11860 585 . 575 305 .7 325 FEB 935 595 715 370 410 MAR 100$ 575 - 895 465 ., 520 510 APR 985 465 .. 1040 _ 625 MAY 995 1230 655 . 690 JUN 935 34 1235 640 660 JUL 945 1215 630

55E- . AUG 1010 470 1145 605

SEPT 1000 530 9E5 490

445 355 OCT 1020 . 640 . 820 275 NOV 880 590 615 325

245 235 DEC 745 500 490 . a .

FIG.4.14. EFFECT OF ORIENTATION ON VERTICAL SURFACES 2500.

1- m 2000

4 cc '1500 cc mist ...... 5 0 . . ... 1 000 and 0 0 g .- 500..

Mu I la Jan. Feb. Mar.Apr. May June July Aug. Sept. Oct. Nov.Dec.

'Radiation *Arkansas;'*Solar Heaters. Be Attached,To

'Radiation Arkansas;'Solar Heaters. Be Attached,To