The Gaz de France Center for gas utilization testing and research (CERUG) based at Plaine Saint-Denis carries on research into the heating and hot water production systems. This article, in its first part, describes the strategy of the CERUG in the field of the energy use in buildings, and in the second part presents the results of the research carried out, with some illustrations. The laboratory and experimental houses are described. The research is centered on the following subjects: hot air heating systems, condensation, new control systems for gas central heating, heating and air conditioning in commercial buildings, 'low temperature' floor heating, and management of the investment costs for heating installations.