. . . "I calculated that my old apartment, with its 80% efficiency furnace, probably uses at a minimum several times this amount to keep the space even at 65 degrees. (Thankfully, my current apartment, in a multi-unit building, doesn???t even have heat and is a constant 65 degrees, for reasons unbeknownst to me.) See the next section for some ideas about a major energy reducing component of the design/re" .