*5.3. Calculation of the Surface Temperature of the Inner Outer Wall*

The temperature of the inner surface of the outer wall is the result of heat conduction through the wall and taking heat from the inner air. It clearly depends on the wall insulation. It was calculated according to the Equation (22) and the results are presented in Figure 10. This temperature and its fluctuations throughout the year clearly depend on the wall insulation.

**Figure 9.** Indoor air temperature.

**Figure 10.** The temperature of the inner surface of the outer wall.

The annual amplitude of changes in this temperature decreases with increasing insulation thickness. In the absence of insulation, the lowest temperatures appear around the beginning of March, and for an insulated wallm around mid-April.

Fluctuations in the average daily temperature ΔTi (Figure 11) with efficient regulation in the heating season are very small during the year (<0.51 ◦C) and depend to a small extent on the wall insulation. On the other hand, the temperature fluctuations of the inner surface of the outer wall Twi depend on the insulation. For a wall without insulation, the maximum difference in a year is 3.14 ◦C. The difference in temperature values when changing the insulation thickness from 5 to 25 cm, equal to 0.49–0.86, is small and it has little effect on thermal comfort.

**Figure 11.** Maximum temperature differences on the inner surface of the outer wall.
