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by Bradford Hatcher
Just about everybody, including architects and engineers, will tell you that an airlock entry is a useful energy-saving feature of a residence. They are wrong, because they haven’t really stopped to think the problem through. A residence is an energy system bounded by its exterior walls. Heat stays inside until it escapes through that outer shell. When you enter an airlock, winter air enters from the outside, to be moderately conditioned by the space inside. When you have your coat and boots off, you enter the main, fully conditioned space. So what happens to the cold air you let into the airlock? It eventually gets reheated by the main house. Energy is not saved. Further, you have significant added embedded energy costs of the construction of the airlock itself. This isn’t to say that airlocks are silly things to build. To have a place to change from outdoor to indoor apparel, and then shut all that behind a door, can enhance the indoor appearance and experience. Further, and maybe more importantly, you are eliminating the unpleasant cold drafts entering the cozy space from the harsh exterior. But people should quit their mistaken thinking that airlocks are an energy-saving feature of a house and decide whether they want one for the other benefits. |