Thermal Mass Wall Finishes for Absorbing & Storing Solar Heat InspectAPedia® -
Design details for a thermal mass heat storage wall for passive solar energy systems
Passive solar design details for thermal mass walls and thermal mass wall finishes or coatings
Questions & answers about how to choose a final coating or finish material, color, etc. for thermal mass walls and passive solar energy systems
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This article discusses the design details, color, coating of a mass wall intended to absorb and store solar heat for a passive solar energy home. Accompanying text are reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss. Our page top photo shows the interior wall of a low-cost passive solar home discussed at this website.
Coating, Color, Design for Thermal Mass Wall for Passive Solar Design
The link to the original Q&A article in PDF form immediately below is followed by an expanded/updated online version of this article.
Mass-Wall Finishes - Q&A on use of drywall over a block wall used for thermal mass storage in passive solar energy design - PDF version, use your browser's back button to return to this page
The question-and-answer article below paraphrases, quotes-from, updates, and comments an original article, (see links just above) from Solar Age Magazine and written by Steven Bliss.
Topic: Use of Drywall over Masonry Block Thermal Mass Wall
Question:
In a passive solar home I am building, the entire first floor is enclosed by vermiculite-filled, 10-inch concrete block externally insulated by 2-inch thick polystyrene insulating board. I am inquiring about the efficiency of covering the interior surface of the masonry block thermal mass wall with drywall that would be attached directly to the block by adhesive.
Will solar-gain heat be absorbed by the drywall and thereby conducted to and stored in the underlying masonry wall? -- David Kallett, Pompton Lakes NJ
Answer:
If the thermal mass walls are intended to absorb and store solar heat, the wall surface should have high absorptance (a dark color) and conductivity that equals or exceeds that of the storage materials themselves (the concrete block) so that heat will flow into the thermal storage wall at least as fast as if the wall were left uncovered.
You mention that most of the walls will not receive direct sunshine (see our photo at page top), but will absorb heat from the room air. In this case the color of the surface [of walls not receiving direct sunlight] has little importance in the heat gain and storage of the mass wall.
Plaster on the block wall would be your best bet, since its internal properties are about the same as concrete block, and it would bond tightly and continuously to the block.
Gypsum board is almost as conductive as concrete block (k = 4.4 vs. 5.0 for concrete block). [See THERMAL MASS in buildings]. More important, however, is the bonding of the gypsum board or drywall to the block wall. Gluing in the typical fashion (beads of glue applied with a caulking gun) will leave air spaces that will impede the heat flow from the drywall into the block wall.
So if you can't plaster the block wall, how about just painting it?
By the way, directly irradiated mass is several times more effective than convectively coupled mass - or in simple terms, a thermal mass block wall that receives direct sunlight is several times more effective than thermal mass walls that do not.
The question-and-answer article about ... , quotes-from, updates, and comments an original article, (see links just above) from Solar Age Magazine and written by Steven Bliss.
Here we include solar energy, solar heating, solar hot water, and related building energy efficiency improvement articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.
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Solar Age Magazine was the official publication of the American Solar Energy Society. The contemporary solar energy magazine associated with the Society is Solar Today. "Established in 1954, the nonprofit American Solar Energy Society (ASES) is the nation's leading association of solar professionals & advocates. Our mission is to inspire an era of energy innovation and speed the transition to a sustainable energy economy. We advance education, research and policy. Leading for more than 50 years.
ASES leads national efforts to increase the use of solar energy, energy efficiency and other sustainable technologies in the U.S. We publish the award-winning SOLAR TODAY magazine, organize and present the ASES National Solar Conference and lead the ASES National Solar Tour – the largest grassroots solar event in the world."
Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education.
Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com.
Excerpts with updates and annotations expanding the original Best Practices Guide text can be found in the online review and book summary at BEST CONSTRUCTION PRACTICES GUIDE and also at DECK & PORCH CONSTRUCTION, at INDOOR AIR QUALITY IMPROVEMENT GUIDE, and in other articles found at InspectAPedia.com such as HOUSEWRAP AIR & VAPOR BARRIERS, SOUND CONTROL in buildings, and other topics.
Passive Solar Design Handbook Volume I, the Passive Solar Handbook Introduction to Passive Solar Concepts, in a version used by the U.S. Air Force - online version available at this link and from the USAF also at wbdg.org/ccb/AF/AFH/pshbk_v1.pdf
Passive Solar Design Handbook Volume II, the Passive Solar Handbook Comprehensive Planning Guide, in a version used by the U.S. Air Force - online version available at this link and from the USAF also at wbdg.org/ccb/AF/AFH/pshbk_v2.pdf [This is a large PDF file that can take a while to load]
Passive Solar Handbook Volume III, the Passive Solar Handbook Programming Guide, in a version used by the U.S. Air Force - online version available at this link and from the USAF also at wbdg.org/ccb/AF/AFH/pshbk_v3.pdf
"Passive Solar Home Design", U.S. Department of Energy, describes using a home's windows, walls, and floors to collect and store solar energy for winter heating and also rejecting solar heat in warm weather.
"Solar Water Heaters", U.S. Department of Energy article on solar domestic water heaters to generate domestic hot water in buildings, explains how solar water heaters work. Solar heat for swimming pools is also discussed.
"Heat-Transfer Fluids for Solar Water Heating Systems", U.S. DOE, describes the types of fluids selected to transfer heat between the solar collector and the hot water in storage tanks in a building. These include air, water, water with glycol antifreeze mixtures (needed when using solar hot water systems in freezing climates), hydrocarbon oils, and refrigerants or silicones for heat transfer.
"Solar Water Heating System Freeze Protection", U.S. DOE,using antifreeze mixture in solar water heaters (or other freeze-resistant heat transfer fluids), as well as piping to permit draining the solar collector and piping system.
"Solar Air Heating" U.S. DOE also referred to as "Ventilation Preheating" in which solar systems use air for absorbing and transferring solar energy or heat to a building
"Solar Liquid Heating" U.S. DOE, systems using liquid (typically water) in flat plate solar collectors to collect solar energy in the form of heat for transfer into a building for space heating or hot water heating. The term "solar liquid" is used for accuracy, rather than "solar water" because the water may contain an antifreeze or other chemicals.
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