The aim of the research is to work out a methodological foundation for the evaluation of an energy efficient technology by designing the thermonergetic parameters of buildings. A multicriterial method is offered for the choice of thermal characteristics and calculation of the envelope of an energy-efficient building using the target function. As the main target function a possibility should be mentioned to employ the requirements of ensuring comfort conditions and microclimate in the rooms of the building. Following the comfort requirements, initial parameters are determined for the rooms in order to calculate thermal characteristics of the envelopes of an energy-efficient building. The energy balance of the building has been determined, as well as the directions of the heat flows and losses through the envelopes. There are given formulae for the calculation of the losses of heat through the envelopes arising as a result of infiltration and ventilation of the building. Fluctuations of the flow are discussed through the envelopes arising due to the variations in the indoor air temperature, as well as the temperature of the internal surfaces of the envelope. Formulae are indicated for the calculation of the heat endurance of the rooms, their envelopes when the indoor temperature and the temperature of the internal surfaces of the envelope are changing.