The efficiency of heat consumption of buildings depends on many factors. Primarily they are space-planning and construction decisions, that is the level of thermal protection of certain claddings and buildings on the whole. In order to improve the thermal protection of buildings currently the multilayer building envelope is used in construction. In this connection, the issue of determining the thermophysical properties, in particular, reduced resistance to heat transfer is relevant. The article presents the results of a field experiment, which object was to estimate the efficiency of the use of lightweight steel frame structure. In the course of the research there were determined the heat flow through the frame structure, the impact of thermoprofiles on temperature conditions in the room, the level of thermal protection. The object of the field observation was one-family dwelling in the Leningrad Region. As a result of researches the reduced resistance to heat transfer and the thermal homogeneity value of lightweight building envelope construction were received.