The warm room retrofit is a response to a common problem: how to stay warm in a large, poorly insulated house during the coldest parts of winter. The problem is especially acute for low-income and elderly homeowners who may not have sufficient resources to improve the thermal integrity of their entire house. Although still an experimental technique, the warm room retrofit has the potential for achieving significant energy savings in houses at costs similar to those currently allocated by low-income weatherization programs. The retrofit is a combination of zoning, heating systems modification and insulation which allows the occupant to heat selected areas of her home while maintaining the unused areas at a cooler temperature. This study presents the results from a retrofit project in Kansas City, sponsored by the Urban Consortium in 1985–1986. Nine houses were selected for the study, four controls and five houses that received the warm room retrofit. The houses are all single-family detached structures, occupied by low-income owners (with the owners' ages between 60 and 80 yr), and heated with gas-fired forced-air or gravity-fed furnaces. The warm zone was designed to include the kitchen, bathroom, and one to two additional rooms depending on family size. The costs of the retrofit averages $1425 per house. Our analysis included regressions of total gas use vs outdoor temperatures to measure savings, which averaged 26%. Because of potential health and safety problems, we also measured indoor air quality before and after the retrofit, sampling levels of indoor radon, nitrogen dioxide, and formaldehyde. An important part of the study was to determine occupant response and the acceptability of the retrofit. The residents participated in the design of the retrofits, and were interviewed after the retrofits were installed to determine improvements in comfort and their satisfaction with the results.