Today, the problem of reducing primary energy consumption is increasingly discussed in the technical literature due to the depletion of fossil fuel resources and the adverse impact of their combustion on the environment. A large amount of energy is spent on heating buildings. In the case of much cheaper waste energy or energy from renewable sources with a temperature lower than required in the rooms, the so-called "thermal barrier" located in the external walls of buildings may be used in order to limit heat losses by transmission. The thermal barrier is an element of the wall with partitions with a heating medium installed in the partition, with a temperature lower than the temperature in the room, but higher in the place of the partition than resulting from heat transfer through the partition without a barrier. In the article, based on the adopted model of a partition with a thermal barrier, a formula for the efficiency of the partition was derived for the parameters characterizing the partition and its surroundings. The efficiency of the thermal barrier does not depend on the temperature of the barrier base, but only on the geometrical and thermodynamic parameters of the partition and the environment. It was also shown that the efficiency of the thermal barrier is the highest when the resistance of the partition on both sides of the barrier is the same. Knowing the efficiency of the barrier will allow you to easily determine the average temperature of the barrier and the amount of heat given off by the room and by the heating medium flowing in the barrier. It should be remembered that the total amount of heat given off through a partition with a thermal barrier is greater than through a partition without a barrier, with a low price of energy given off by the barrier, the costs of heating the room may be lower.