A two-thirds reduction in the space heat requirement of a Twin Rivers townhouse

Abstract

A Twin Rivers townhouse received a series of retrofits more extensive than those deployed in previous experiments at Twin Rivers, and a 67% reduction in annual energy use for space heating resulted. The retrofits included interior window insulators of various designs, basement and attic insulation and systematic attention to routes of air infiltration. The 67% reduction was approximately the savings anticipated by a simple model, in which the "second role" of insulation in improving the retention of the non-furnace heat from sun, appliances, and people appears explicitly. (In the absence of non-furnace heat, the savings of gas achieved would have been only 50%.) The retrofits appear to be a financially attractive investment at the present price of natural gas and a 10% return on investment. Further retrofits are discussed.