DOCSLIB.ORG

Criteria for Humidity in the Building and the Buidling Envelope

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Criteria for Humidity in the Building and the Buidling Envelope November, 1993 63 Criteria for Humidity in the Building and the Building Envelope Anton TenWolde and William B. Rose In: Rose, William B.; TenWolde, A., eds. Bugs, mold rot, II: Proceedings of workshop on control of humidity for health, artifacts. and buildings; 1993 November 16–17; [Oak Ridge, TN]. Washington, DC: National Institute of Building Sciences; 1994: 63–65. This symposium intended to bring together a THE NEED FOR HUMIDITY CRITERIA wide variety of building professionals and building When building professionals and building owners users to discuss the multiple aspects of humidity in ask the question “what humidity should I maintain the building, and begin the process of defining better criteria for humidity in buildings. In this paper we in my building?” they usually do not get a satisfac- tory answer. The reason for this is that the question present some basic concepts and issues that should be considered when formulating humidity criteria. is difficult to answer. The “right” answer very much These issues are often related and involve human depends on what is in the building (artifacts, people, health and comfort, building use, surface moisture plants), the priorities of the building owner or occu- and humidity, and resistance of building materials pants, and the building construction details, espe- to moisture. cially details regarding the thermal integrity of the building envelope. It is important to maintain hu- midity conditions that meet the needs of the people HUMIDITY CRITERIA FOR HUMAN HEALTH AND and things inside the building without destroying COMFORT the building itself. Humidity and moisture can espe- cially become an issue when there is a change in ASHRAE Standard 55, Thermal Environmental building use or occupancy. Changes in ventilation, in- Conditions for Human Occupancy is perhaps the door RH, moisture release, or building air pressures most widely known standard for indoor humidity in can create moisture problems in a building where the United States. This standard defines one tem- there were none before. Perhaps it is possible to pro- perature comfort zone for winter and one for sum- vide better guidance to building owners and occu- mer. In the 1981 version of Standard 55 the comfort pants in making decisions about humidity and humidity range was defined in terms of dew point building use. temperature, and ranged from 35°F (1.7°C) and 62°F (16.7°). This translates into approximate RH ranges Building researchers and consultants also have of 25% to 80% in winter and 20% to 70% in summer, long had a need for criteria to determine if a build- depending on temperature. Although ASHRAE 55- ing or building component will be operating satisfac- 1981 professes to be based on considerations of respi- tory. Better tools for calculating moisture contents of ratory health, mold growth, and other moisture building design and materials in service are begin- related phenomena, the 1981 version appears to be ning to become available (e.g. the MOIST computer primarily a human comfort standard. It appears model), but no agreed-upon criteria exist as yet to from the 1981 version that people are not particu- evaluate the results obtained with those tools. For larly sensitive to relative humidity and are comfort- many years avoidance of surface condensation and able in a wide range of RH conditions. However, the various saturation moisture content criteria were 1992 version of ASHRAE Standard 55 contains a used. These criteria were aimed at prevention of de- drastically reduced upper RH limit of 60% RH, win- cay and structural damage to building materials. ter and summer, which coincides with the upper RH For instance, some have used a wood moisture con- limit recommended by Sterling et al. (1985). This tent of 20% or higher as a criterion for moisture prob- lower upper limit apparently reflects a concern for lems, while others have used fiber saturation mold and mildew growth and health, not comfort. (around 30% MC for solid wood). More recently mold The Canada Department of National Health and and mildew growth has been recognized as a basis Welfare (1987) recommends RH ranges of 30% to for performance criteria, resulting in criteria for sur- 80% in summer and 30% to 55% in winter, based on face relative humidity. A consensus on the “best” cri- comfort and health considerations. Apparently, the teria would be of use to many building professionals. winter maximum of 55% is based on the danger of condensation or mold growth. Neither the ASHRAE 64 Bugs, Mold & Rot II Proceedings standard nor the Canadian criteria recognize the im- The authors believe that a maximum 80% portance of microclimates and the moisture/thermal monthly average surface relative humidity is a use- integrity of the building envelope. Finally, to control ful criterion for building professionals. In addition to dust mite population it has been recommended that relative humidity a simultaneous temperature crite- indoor humidity be maintained below 45% (Pope, rion should be defined. This becomes especially criti- Patterson and Burge 1993). Mites reproduce over a cal when assessing the potential for mold growth in range of 45 to 80 % RH, but 65°F to 80°F (18°C to unheated spaces or building envelope cavities. Al- 27°C) and 75% to 80% RH appear to be optimal for though various molds can grow at a wide variety of dust mite growth (Anderson and Korsgaard (1986). temperatures there seems to be agreement in the lit- erature that molds generally will grow at tempera- This much is clear from reviewing the various rec- tures between 32°F and about 104°F (0°C and 40°C). ommendations and criteria: Mold may survive but will not grow at temperatures below 32°F, and mold will generally not survive pro- 1) RH criteria for human comfort are not very longed exposure to temperatures above 104°F restrictive. (Hunter and Sanders 1991). It seems therefore ap- propriate to use a temperature criterion of 32°F to 2) Recommendations for RH criteria for human 106°F concurrent with the RH criterion. health are more restrictive but vary widely. 3) None of the above criteria sufficiently recognize OTHER CRITERIA the importance of microclimates and the build- ing envelope. Special humidity requirements may override or be imposed in addition to the above requirements for The authors believe that at this time it is more human comfort or health. Examples are special envi- useful to define humidity criteria for occupied spaces ronmental requirements in museums, libraries, and on the basis of human comfort, and to deal with swimming pools. These criteria may contain not only health issues in terms of surface RH and tempera- humidity levels, but also criteria for rate of change ture criteria. Exceptions may be special require- in humidity. At this time we will confine ourselves to ments for occupants with extreme sensitivities or mentioning the need to consider any such special re- allergies. This would indicate that comfort criteria quirements. for "middle of the room" RH should be according to the "old" ASHRAE Standard 55. Concerns for degradation or dimensional stability of building materials may also supersede the other criteria for humidity. Concerns for dimensional sta- HUMlDlTY CRITERIA AT BUILDING SURFACES bility of wood building products during cold weather, when temperatures are too low for growth of mold or As David Miller states in his concluding remarks decay organisms, is one example. James Connolly, in in these proceedings: there is a consensus that fungi his article elsewhere in these proceedings, cites cy- should not be allowed to grow in buildings. He also clic condensation deteriorating paint finishes as an- points out that favorable conditions for mold growth other example. He also includes a list of suggested vary with mold species and substrate. However, maximum moisture contents for a variety of materi- building professionals need a simple standard or cri- als under different conditions. This list is a very use- terion by which to judge the likelihood for mold ful tool but obviously needs further discussion and growth in new construction or retrofits, as was clear expansion. from comments from the audience during the sympo- sium. Recognizing the complexity of the issue but re- sponding to this need, the International Energy RECOMMENDATIONS Agency Annex XIV proposed a simple performance criterion for building surfaces: the monthly average On the basis of previously reported data as well water activity of a material surface should not ex- as information presented at this symposium we put ceed 0.8 (see the paper by Hens in these proceed- forward a set of interim performance criteria for hu- ings). Water activity is the ratio of water vapor midity inside the building as well as the building en- pressure in the substrate and that of pure water at velope. These criteria are all in force simultaneously, the same temperature and pressure. For practical but one or two may govern at any given time, loca- purposes monthly average water activity may be tion, or building design. We realize that these recom- equated to monthly average RH at the surface of the mendations are not based on consensus, and on material. Thus average monthly RH at the surface incomplete information in some areas. should remain below 80%. Only for non-porous mate- rials which are regularly cleaned (glass, metals, a. Occupied zones: Relative humidity in the glazed tiles, etc), avoiding prolonged surface conden- center of the occupied zone should be main- sation should be made the criterion. tained between 25% and 80% in winter and November, 1993 65 20% to 70% in summer. basis: ASHRAE 55-1981. b. Interior surfaces and building cavities: Monthly mean RH less than 80% at all interior build- ing surfaces, including building envelope cavi- ties, if concurrent monthly mean temperature at same surfaces between 0°C (32°F) and 40°C (104°F).
Load more

Recommended publications
  • Investigation of the Impact of Commercial Building Envelope Airtightness on HVAC Energy Use
    NISTIR 7238 Investigation of the Impact of Commercial Building Envelope Airtightness on HVAC Energy Use Steven J. Emmerich Tim McDowell Wagdy Anis NISTIR 7238 Investigation of the Impact of Commercial Building Envelope Airtightness on HVAC Energy Use Steven J. Emmerich Building and Fire Research Laboratory Timothy P. McDowell TESS, Inc. Wagdy Anis Shepley Bulfinch Richardson and Abbott Prepared for: U.S. Department of Energy Office of Building Technologies June 2005 U.S. Department of Commerce Carlos M. Gutierrez, Secretary Technology Administration Phillip J. Bond, Under Secretary of Commerce for Technology National Institute of Standards and Technology Hratch Semerjian, Acting Director ABSTRACT This report presents a simulation study of the energy impact of improving envelope airtightness in U.S. commercial buildings. Despite common assumptions, measurements have shown that typical U.S. commercial buildings are not particularly airtight. Past simulation studies have shown that commercial building envelope leakage can result in significant heating and cooling loads. To evaluate the potential energy savings of an effective air barrier requirement, annual energy simulations were prepared for three nonresidential buildings (a two-story office building, a one-story retail building, and a four-story apartment building) in 5 U.S. cities. A coupled multizone airflow and building energy simulation tool was used to predict the energy use for the buildings at a target tightness level relative to a baseline level based on measurements in existing buildings. Based on assumed blended national average heating and cooling energy prices, predicted potential annual heating and cooling energy cost savings ranged from 3 % to 36 % with the smallest savings occurring in the cooling-dominated climates of Phoenix and Miami.
    [Show full text]
  • Download the Brochure
    The trusted partner that clients continually rely upon to solve their most complex design challenges and building issues serviced through an exceptional consultant experience. WE DELIVER SUSTAINABLE BUILDING SOLUTIONS WHILE RESPECTING ASPIRATIONAL PROJECT GOALS. WE BUILD LASTING RELATIONSHIPS WITH OUR CLIENTS, COLLABORATORS, AND EACH OTHER. WE ARE FOCUSED ON PROJECT EXECUTION AND EXCEL AT CLIENT DELIVERABLES AND CONSULTING SERVICES. Firm Profile DeSimone Consulting Engineers provides high-quality structural engineering, facade consulting, and forensic services, in addition to risk management and construction claims consulting for all types of buildings. Known for the highest quality of service, the firm provides each client with personal, dedicated, and inspiring engineering solutions. Founded in New York City in 1969, the firm is organized to support clients around the country and around the globe with offices in the United States, South America, and the Middle East. To date, DeSimone has designed over 10,000 projects in 44 states and 55 countries. Our project portfolio demonstrates the firm’s dedication to pursuing and developing superlative structures. The firm is also consistently listed on Engineering News Record’s Top 500 Design Firms. DeSimone produces extremely efficient designs and is known for creative thinking and for outright innovation. The firm combines cutting edge technology with seasoned experience to provide professional services unmatched in the industry. DeSimone’s approach is process driven, utilizing an open office, collaborative design environment. Technology, communication, and responsiveness are key strengths that facilitate the firm’s commitment to exceptional service, and engender the creation of a better-built environment. Global Presence DeSimone has offices throughout the United States, the Middle East, and South America.
    [Show full text]
  • Effects of Climate Change on the Moisture Performance of Tallwood Building Envelope
    buildings Article Effects of Climate Change on the Moisture Performance of Tallwood Building Envelope Maurice Defo * and Michael A. Lacasse National Research Council Canada, 1200 Montreal Road, Ottawa, ON K1A 0R6, Canada; [email protected] * Correspondence: [email protected] Abstract: The objective of this study was to assess the potential effects of climate change on the moisture performance and durability of massive timber walls on the basis of results derived from hygrothermal simulations. One-dimensional simulations were run using DELPHIN 5.9.4 for 31 con- secutive years of the 15 realizations of the modeled historical (1986–2016) and future (2062–2092) climates of five cities located across Canada. For all cities, water penetration in the wall assembly was assumed to be 1% wind-driven rain, and the air changes per hour in the drainage cavity was assumed to be 10. The mold growth index on the outer layer of the cross-laminated timber panel was used to compare the moisture performance for the historical and future periods. The simulation results showed that the risk of mold growth would increase in all the cities considered. However, the relative change varied from city to city. In the cities of Ottawa, Calgary and Winnipeg, the relative change in the mold growth index was higher than in the cities of Vancouver and St. John’s. For Vancouver and St. John’s, and under the assumptions used for these simulations, the risk was already higher under the historical period. This means that the mass timber walls in these two cities could not withstand a water penetration rate of 1% wind-driven rain, as used in the simulations, with a drainage cavity of 19 mm and an air changes per hour value of 10.
    [Show full text]
  • Tierra-Linda-Passive-House-Design
    TIERRA LINDA Passive House Design About The Project In July 2014, Latin United Community Housing Association (LUCHA) led an interactive eco-charrette to generate and target sustainability goals for its new wellness-centered scattered-site housing development called Tierra Linda, located near the 606 Trail in Humboldt Park. The project kick-off brought together members of the LBBA design team with the maintenance staff, tenants, and neighbors of the future development and introduced the benefits of “green” housing and collaboratively developed a vision and strategies for the project. LUCHA incorporated key tactics into the development of Tierra Linda that supports the core theme of healthy living and wellness integrated amongst tenants and the community. The project has received Passive House certification—the first affordable multi-family housing type to achieve PH certification in Chicago! In addition to the Passive House 6-flat, the development also includes a “twin” building that is designed to comply with code-minimum energy requirements which will allow the team to compare energy usage between the two. What Is Passive House? Passive House is a building standard popular in Europe and Canada. However in recent years, Passive House Alliance launched a United States program aimed at making high- performance passive building the mainstream market standard. Passive building is made up of a set of design principles used to attain rigorous level of energy efficiency within a quantifiable comfort level. To that end, a passive building is designed and built in accordance with these five building science principles: 1. Employs continuous insulation throughout its entire envelope without any thermal bridging.
    [Show full text]
  • Analysis for Building Envelopes and Mechanical Systems Using 2012 CBECS Data March 2018
    PNNL-26949 Analysis for Building Envelopes and Mechanical Systems Using 2012 CBECS Data March 2018 DW Winiarski AL Cooke MA Halverson GK Bandyopadhyay JB Butzbaugh DB Elliott Prepared for the U.S. Department of Energy under Contract DE-AC05-76RL01830 PNNL-26949 Analysis for Building Envelopes and Mechanical Systems Using 2012 CBECS Data DW Winiarski AL Cooke MA Halverson GK Bandyopadhyay JB Butzbaugh DB Elliott March 2018 Prepared for the U.S. Department of Energy under Contract DE-AC05-76RL01830 Pacific Northwest National Laboratory Richland, Washington 99352 Summary This report describes the aggregation and mapping of certain building characteristics data available in the most recent Commercial Building Energy Consumption Survey (CBECS) (DOE EIA 2012) to describe most typical construction practices. Buildings with a date of construction of 1990 or later (referred to as post-1990) were analyzed as a reflection of more recent building construction practices. This report provides summary data for potential use in the support of modifications to the Pacific Northwest National Laboratory’s (PNNL’s) commercial prototype building models (prototypes) used for building energy code analysis. Mapping of CBECS data to building construction characterized in the building code was conducted to provide actionable insight. This summary outlines findings and most typical design choices for certain building envelope and heating, ventilating, and air-conditioning (HVAC) systems for the prototypes based primarily on the most recent CBECS data. While the conclusions in this summary are reflective of current construction, as captured in the CBECS data, the commercial building prototypes form the basis of other analytical work for PNNL, and any subsequent modifications to the prototypes based on the findings in this report should take into account the historical use of the prototypes as well as other data used in their development.
    [Show full text]
  • Analysis of Cooling Load Calculations for Underfloor Air Distribution Systems
    The 13th Asia Pacific Conference on the Built Environment: Next Gen Technology to Make Green Building Sustainable , 19-20 Nov 2015 (Thu-Fri), Hong Kong. Analysis of cooling load calculations for underfloor air distribution systems Dr. Sam C. M. Hui * and Miss ZHOU Yichun Department of Mechanical Engineering, The University of Hong Kong Pokfulam Road, Hong Kong * E-mail: [email protected] Abstract Underfloor air distribution (UFAD) systems use an underfloor supply plenum located between the structural floor slab and a raised floor system to supply conditioned air through floor diffusers or terminal units directly into the building’s occupied zone. If designed properly, they have the potential to enhance energy efficiency, indoor air quality and building life cycle performance. However, the application of UFAD system is still obstructed by the information gap in some fundamental issues, such as cooling load calculation. All the cooling load calculation methods for UFAD systems nowadays have limitations and drawbacks and most building designers are not familiar with them. This research aims to investigate the cooling loads calculation methods for UFAD systems. Fundamental principles of UFAD with different configurations are studied to analyse the effects on cooling load components. Critical evaluation is made on the key factors and issues affecting the cooling load and how they differ from the overhead air distribution systems. It is found that thermal stratification, management of solar and lighting loads, architectural design and thermal properties of structural floor slab will influence the cooling load and must be evaluated carefully. It is hoped that the findings could improve the understanding of UFAD systems and provide practical information for performing the cooling load calculations and optimising the system performance.
    [Show full text]
  • Envelope Durability Problems in High-Humidity Buildings
    ENVELOPE DURABILITY PROBLEMS IN HIGH-HUMIDITY BUILDINGS Mark Lawton, P.Eng. David Scott ABSTRACT This paper exalllilies envelope durabilily pmblellls ill higll­ attribuled 10 Ihe exfiltmlioll of 1II0isi air ililo cavilies oulside Ihe hUlllidily buildillgs such as museullls alld Ihose cOlilaillilig illsula liolilayer of Ihe ellvelope asselllblies. The buildillg ellvelope swilllmilig pools by preselililig a series of brief case sludies. failures occulTed due 10 problems ill desigll alld collslmelioll of All buildillgs are localed ill cold-clilllale areas wilhill Callada. Ihe buildillg Cl/Velope alld opemlioll of Ihe buildillg's lIIechallical Moislure dalIIage foulld could, for Ihe 1II0si pari, be syslellls. INTRODUCTION Site Observations High-humidity buildings in cold Canadian climatic Thermographic scalU1ing provided evidence of air zones provide a serious challenge for building envelope leakage along the upper parapet at the junction of the design teams. Operating conditions for building humid­ sloped roof to wall and at locations on the wall cladding. ity and the possible mechanical pressurization of the building during operation must be balanced against the cost of the building envelope, its constructability with average labOl~ and its serviceability over time. Often, too little emphasis is placed on critical transition details to provide a continuous, structurally supported air barrier. CASE #1 TIle first exatnple COllles £r0111 a recreation facilit)~ constructed in 1975 in central Canada, whose Inajar fea­ ture is a swinuning pool. The building is maintained at approximately 45% relative humidity (RH). Building operations staff attempt to maintain a slight positive interior pressure relative to the exterior to control cold drafts. The building has an upper roof deck and sections of lower-level roofs, some flat and some sloped.
    [Show full text]
  • 36.Pdf [517Kb]
    A NOZZLE PULSE PRESSURISATION TECHNIQUE FOR MEASUREMENT OF BUILDING LEAKAGE AT LOW PRESSURE Edward Cooper*1, Xiaofeng Zheng1, Mark Gillot1, Saffa Riffat1 and Yingqing Zu2 1 Architecture, Climate and Environment Research 2 Department of Mechanics and Engineering Science, Group, Faculty of Engineering, University of Fudan University Nottingham, University Park, Nottingham NG7 2RD, 220 Handan Road, Shanghai, China UK *Corresponding author: [email protected] ABSTRACT Air tightness is essential to building energy performance, which has been acknowledged for a long time. It plays a significant role in improving building energy efficiency by minimising the heating/cooling loss incurred during unwanted air movement through the building envelope, consequently reducing the building’s energy demand and cutting down carbon emission in the building sector. A novel nozzle pulse pressurisation technique for determining the adventitious leakage of buildings at low pressure around 4 Pa, which is regarded as a more accurate indicator than conventional steady state measurement at 50 Pa, is investigated theoretically, numerically and experimentally. The investigation is based on the ‘quasi-steady pulse’ concept which produces a pressure pulse inside the building by introducing a certain amount of air in a very short time using an air compressor, solenoid valve, nozzle and control unit. The mass flow rate from the nozzle is obtained by measuring the transient pressure in the air receiver of the compressor during a test run. Simultaneously, the pressure difference across the building envelope is measured by differential pressure transducers. The quadratic equation, which can more closely represent the flow characteristics of adventitious openings, is used to determine the characteristic of building air leakage.
    [Show full text]
  • Building Envelope a Guide to Building Envelope Solutions That Improve Comfort, Marketability, and Energy Efficiency
    solution package Building Envelope A guide to building envelope solutions that improve comfort, marketability, and energy efficiency. The BE-Ex solution packages are a suite of six documents compiled from the Anatomy of an Energy Efficient Building exhibit on view at Building Energy Exchange’s downtown resource center, or virtually at be-exchange.org/anatomy system interaction operations & maintenance The performance of mechanical building systems is contingent on Investing in operations and maintenance best practices ensures the integrity of the building envelope. Building envelope upgrade that building systems run optimally, enabling proper performance decisions should be made in the context of how they might impact in existing equipment and maximizing return on investment in new the operation and performance of mechanical systems. systems. Best practices for building envelopes include: • Weatherstrip windows and door frames, replace gaskets, and air seal around air conditioners, vents, shaft openings, piping penetrations, and cracks along walls and joints. heating hot water • Routinely inspect building for air and heat leakage using 2 infrared cameras to identify thermal bridges and smoke blowers to locate air leaks. 1 • Inspect each envelope component from both the exterior and interior of the building. envelope 2 ventilation • Establish a winter maintenance policy for window and through-wall air conditioners. • Apply reflective, light-colored paint to the building’s roof. cooling lighting & loads 1 envelope → ventilation Envelope upgrades must be paired with balanced fresh air ventilation to ensure indoor air quality and health benefits. 2 envelope → heating & cooling Improvements to the building envelope will reduce the need for heating and cooling, saving energy and minimizing operating costs.
    [Show full text]
  • Building Envelope Standards 401
    Part 4. Building Envelope Standards 401. Introduction A. The BUILDING ENVELOPE STANDARDS (BES) establish both the limita ons and specifi c requirements for building form and frontages. B. The form and func on controls work together to create the STREET SPACE while allowing the building design greater la tude behind the façades. 402. General Standards The following regula ons apply to all BES, unless expressly stated otherwise within an individual BES or on the REGULATING PLAN. A. Transitions When the BES designa on changes along the STREETSPACE FRONTAGE or at the BLOCK CORNER within a DEVELOPMENT PROJECT or BES SITE, the applicant has the op on of applying either BES for a maximum addi onal distance of 50 feet along that STREETSPACE FRONTAGE or around that BLOCK CORNER. B. Façade Composition 1. The average length of the COMPLETE AND DISCRETE VERTICAL FACADE COMPOSITIONS along a FAÇADE on a BLOCK FACE shall be no more than 100 feet for Urban Mixed-Use and Urban Residen al frontages, and 120 feet for Townhouse/Small Apartment frontages. DEVELOPMENT PROJECTS with STREETSPACE frontage of less than 120 feet on a BLOCK FACE are exempted from the COMPLETE AND DISCRETE VERTICAL FACADE COMPOSITION requirement for that BLOCK FACE. Provided, however, that the COMPLETE AND DISCRETE VERTICAL FACADE COMPOSITIONS maximum length requirements above do not apply to buildings within ADJACENT TO CONSERVATION AREAS. 2. The average distance between STREETSPACE entry doors shall be no greater than 60 feet for each FACADE. Provided, however, that each COMPLETE AND DISCRETE VERTICAL FACADE COMPOSITION shall include at least one func oning entry door from the STREETSPACE.
    [Show full text]
  • Numerical Analysis of Building Envelope with Movable Phase Change Materials for Heating Applications
    applied sciences Article Numerical Analysis of Building Envelope with Movable Phase Change Materials for Heating Applications Alvaro de Gracia * GREiA Research Group, INSPIRES Research Centre, University of Lleida, Pere de Cabrera s/n, 25001 Lleida, Spain Received: 26 July 2019; Accepted: 3 September 2019; Published: 5 September 2019 Abstract: Latent heat storage materials have been tested by several researchers for decades to be used as passive heating and cooling systems in buildings but their implementation into building components is still stacked as is facing specific technical limitations related to difficulties to be charged both in heating and cooling periods. This paper presents a numerical analysis to evaluate the potential of a disruptive system, which is designed to solve the main drawbacks and to convert phase change materials (PCM) passive heating technology into a competitive solution for the building sector. The novel technology moves PCM layer with respect to the insulation layer inside the building component to maximize solar benefits in winter and be able to actively provide space heating. Design variables such as PCM melting point and control schemes were optimized. The results demonstrated that this technology is not only able to limit heat losses towards outdoors but it can provide space heating from stored solar energy when required. The promising numerical results endorse the possibility to build a future experimental prototype to quantify more in detail the benefits of this system. Keywords: phase change material; low energy buildings; climate adaptive building shell; solar energy 1. Introduction Building envelopes have a crucial impact on building energy use for space heating and cooling systems and their designs are crucial to reduce these loads while maintaining the occupants thermal comfort [1].
    [Show full text]
  • IAQ and Energy Impacts of Ventilation Strategies and Building Envelope Airtightness in a Big Box Retail Building
    IAQ and Energy Impacts of Ventilation Strategies and Building Envelope Airtightness in a Big Box Retail Building Lisa Ng Andrew Persily Steven J. Emmerich Engineering Laboratory, National Institute of Standards and Technology 100 Bureau Drive Gaithersburg, MD 20899 Content submitted to and published by: Building and Environment U.S. Department of Commerce Penny Pritzker, Secretary of Commerce National Institute of Standards and Technology Willie E May, Director DISCLAIMERS Certain commercial entities, equipment, or materials may be identified in this document in order to describe an experimental procedure or concept adequately. Such identification is not intended to imply recommendation or endorsement by the National Institute of Standards and Technology, nor is it intended to imply that the entities, materials, or equipment are necessarily the best available for the purpose. Any link(s) to website(s) in this document have been provided because they may have information of interest to our readers. NIST does not necessarily endorse the views expressed or the facts presented on these sites. Further, NIST does not endorse any commercial products that may be advertised or available on these sites. IAQ and Energy Impacts of Ventilation and Source Control in a Big Box Retail Building Lisa C. Ng, Andrew K. Persily, and Steven J. Emmerich ABSTRACT Heating, ventilating, and air conditioning (HVAC) systems in buildings are designed to provide thermally comfortable conditions and to maintain acceptable indoor air quality (IAQ). At the same time, the operating costs of HVAC systems are often a large percentage of the total energy consumption of buildings, which constitutes 40 % of the primary energy consumed in the U.S.
    [Show full text]