This Research Update presents the status of the Existing Buildings Research program of the Office of Building Technologies of the US Department of Energy for the period 1989-199 1. This program covers research on energy efficiency improvements for the residential and commercial buildings in this country. ne Existing Buildings Research program has contributed to significant improvements in energy efficiency of existing buildings by development of improvements to retrofit technologies, by coordinating and conducting research studies on the use of energy efficiency technologies (to reduce barriers and increase use), and by continually evaluating changes in technologies that could improve and maintain buildings energy efficiency. If the energy efficiency of the buildings sector in this country is to be dramatically improved over the next 30 years, we must improve the use of energy efficiency technologies. Improved delivery of measures, improved understanding of how buildings actually perform in the field, and methods for improving operations and maintenance of buildings and energy equipment are all examples of ways to improve the deployment (transfer) of technologies. Much has been learned about technology deployment in buildings in the first five years of the program, and our future plans will be directed at continuing the improvements andmore » making a real contribution to the energy efficiency future of the United States.« less