Two building’s components – the envelope and the air-conditioning system - have the major impact on building’s energy efficiency. As a rule, the building’s envelope is a passive element and the air-conditioning system is an active element regarding the possibility of regulation in order to ensure optimal indoor air parameters. The paper analyses values of building’s envelope’s thermal resistance factor depending on outdoor air parameters. Currently different technical decisions exist for regulation of thermal performance of building’s envelope: double skin facades, multiple films on windows, ventilated curtain walls, automated Venetian blinds. The paper is devoted to the analysis of possibilities to integrate building’s envelope with controlled thermal resistance into air-conditioning system working regimes. The combination of working parameters of air-conditioning system and building’s envelope’s thermal resistance in summer, when the electricity demand for cooling is maximal, could provide the way for significant energy save in public buildings.