The influence of the IR reflection of painted facades on the energy balance of a building

The investigation on the effect of painted facades with spectrally selective properties on the energy balance of a building is made by comparing real measured data from an outdoor test of facade samples with data calculated using the ESP-r simulation program. The following factors were investigated: influence of solar radiation, calculated with a solar model, the absorption of direct solar radiation as a function of the angle of incidence, IR radiation exchange and the influence of heat loss caused by convection. During this investigation, it was determined that the influence of solar radiation and especially the heat loss caused by convection are the most dominant influences on the examined energy balance of a building. After adapting the simulation program in order to simulate the data correctly, the influence of selective facades is investigated using an office model as an example. In the case of the location of Freiburg, Germany, two different types of outer walls are investigated and described in this publication: A well-insulated wall with a U-value of 0.42 W/(m2 K) and a poorly insulated wall with 1.95 W/(m2 K). The savings in the heating demand are higher in the case of poorly insulated walls than in well-insulated walls. In contrast to this effect, the cooling demand increases nearly in the same way for both types of walls. The tendency for condensation is also weakened, as is documented in [4].