To solve the problem of improving the energy efficiency in buildings the materials with low thermal conductivity are used. The constructive difficulty of the modern walling and the heterogeneity of materials must be carefully calculated in designing, constructing and operating of buildings.

The method of thermotechnical calculation based on the determination of the additional heat loss through heat-conducting inclusions (on the example of the jamb construction unit) has been considered in this work. The determination of the value of additional heat flows is carried out by calculating the temperature fields.

The results show that the value of the additional heat flows depends not only on the constructive solution of nodes, but also on the architectural design of buildings. That’s why it is necessary to define a reduced thermal resistance for each building’s facade. The proportion of heat loss through consideration of heat-conducting inclusion of major heat loss, calculated by design coats, can reach more than 20%.