LBNL Report Number
In both the U.S. and Europe, multifamily buildings use a significant fraction of (non-transportaion) oil and have increasingly been targeted by residential energy conservation and research programs. LBL and several European collaborators have compiled and analyzed measured data on retrofit savings and cost-effectiveness for 150 fuel-heated U.S. multifamily retrofit projects and 130 projects in Europe. Energy savings in the U.S., France, and Sweden were typically 14-18% pre-retrofit energy use for space heat and hot water. Swiss buildings save about 23%, but with much higher investments in conservation and greater emphasis on shell insulation rather than (lower-cost) heating system improvements. Median simple payback times for U.S. multifamily buildings were about 5 years; paybacks for the European retrofits were three to six times longer. In each country, heating system measures were generally more cost-effective than shell improvements, due to lower retrofit costs and comparable savings. Even after retrofit, the U.S. multifamily buildings used significantly more energy than the European buildings. This comparison, as well as the types of retrofits observed in the U.S. projects, suggest that many opportunities remain for improving efficiency in existing U.S. multifamily buildings.