The low-energy-house laboratories at the Building Research Station incorporate various techniques for reducing energy consumption for space and water heating. They have been built to high standards of insulation, but the main experimental features concern the eight heat pumps. most of which have been purpose designed for their particular applications. In this paper the houses and their heating systems are described briefly and. whilst these are only experiments, it is expected that some may indicate cost-effective ways in which heat pumps may be employed in both new and existing construction in the future.