12/16/2023 0 Comments Smart wall insulation![]() I do not understand the physics of this, even after watching the video a few times, but evidently it is not just an attribute of the new high tech materials according to Alex: The goal is low permeability in the winter when humidity is low but it’s critically important to block moisture flow and prevent condensation, and high permeability in the summer when humidity is higher and you want drying potential to both the interior and exterior. Instead of an old-school vapor barrier it has what is now known as a “smart vapor retarder.” Alex Wilson of BuildingGreen explains that it changes with the seasons: From the inside, there is a service cavity behind the drywall for wiring, so that electrical boxes and wires do not have to penetrate the membrane. We will look into that question in a separate post, and besides, the wall is more than just wool insulation. Water, the world's most precious resource, plays a big role, too, from raising the sheep to cleaning the fiber it takes approximately 500,000 liters of water to manufacture a metric ton of wool. In New Zealand, home to 45 million sheep (to under 5 million people), more than half of the nation's greenhouse gas emissions come from their livestock the methane that the sheep so conspicuously add to the atmosphere has a global warming potential of 21, compared to (a much smaller) 1 for carbon dioxide. But I will sheepishly admit that I have not been a fan of wool insulation, in the belief that it actually has a high carbon and water footprint. And instead of giving off toxic chemicals, it actually sequesters them. Unlike other insulations like cellulose, there is no borax needed to control rodents and fire. These claims are fact, not conjecture or marketing speak. It is also entirely renewable and sustainable in its creation, a great insulator that has evolved over thousands of years, and compostable at the end of an extended useful life. It is scientifically understood that wool manages moisture against 65% relative humidity, irreversibly bonds with formaldehyde, nitrogen oxide and sulfur dioxide, and the trade is responsible for the sequestration of 525,000 tons of pure, atmosphere-derived carbon. Wool is terrific insulation ask any sheep. If a building wall or a house can’t dry out, it can lead to all kinds of bad things. Such walls can trap moisture and may become exceedingly difficult dry out. ![]() Most every wall out there is built with toxic materials and ends up being too vapor retarding and even vapor-closed. That’s why this “Smart Wall” developed by Lucas Johnson of 475 High Performance Building Supply and Andrew Legge of Havelock Wool is so interesting. It’s also smart to use healthy materials that don’t burn easily or are full of flame retardants, or are made from fossil fuels. You want to stop air movement but not moisture movement. A few years ago when everyone was writing about the smart home, I wrote In praise of the dumb home, which is so well insulated with temperatures so stable that a Nest smart thermostat would be bored stupid.īut designing the walls for a dumb home is not as simple as simply adding insulation you have to be smart about managing moisture and condensation.
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