Currently in Russia during the economic crisis the issue of increasing energy efficiency of buildings and structures is very relevant. Every year, developing new rules and regulations, laws and regulations aimed at improving the thermal efficiency of the building envelope, improving heating systems, increasing the controllability of receipt of heat and light in the room. This article discusses the possibility of increasing the degree of energy efficiency on the example of a public building through the application of energy-efficient building envelopes. The comparison of results of calculations of heat and power parameters of the building for two types of walling, analyzes their advantages and disadvantages. As a result - the definition of the class of energy efficiency of public buildings, to identify the most energy-efficient building envelopes.