August 2012: Thermal Mass

Thermal Mass

It has long been understood that if you could incorporate thermal mass into a building that it will dramatically lower the heating and cooling loads for the dwelling both in the design phase and or as part of a deep retrofit. When we are talking about thermal mass, we are talking about materials that can store and release thermal energy over long sustainable periods (solid concrete, bricks, water, straw bales, adobe, earth, and in some cases what is known as phase change materials). Besides offering a tempering influence, the pure volume of mass to floor ratio can have a small or dramatic effect: the size, type, location and construction. Architects that design and intentionally incorporate these materials into buildings understand the role they can play in diminishing long term energy consumption.

Having been employed by an insulation contractor specializing in exterior wall insulation systems, I saw firsthand the potential of this strategy. If you could feasibly wrap a concrete shell with a durable system you could essentially take all that mass that was negatively impacting the building and thus move it to the “inside” and use it to diminish the load by some 75-80%. Though the upfront costs maybe significantly higher than simply re-siding the building, when one looks at the return on investment and diminished maintenance costs, it starts to make sense. Incorporating mass has simpler applications as in the following adaptations: exposed foundation walls, exposed crawlspace walls, masonry walls to garages, fireplaces and slabs that can be accessed from below to name a few. Good building scientists/contractors should always be on the lookout for these unique opportunities.


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