To identify promising fields of application, a parameter study with a building simulation pro­gram was carried out. For this reason we implemented the possibility to calculate nonlinear thermal properties of construction materials in the simulation environment esp-r. We fo­cused on applications with PCMs in the interior wall materials to prevent overheating and reduce the cooling load in summer and heating energy in winter.

Especially the melting temperature was varied with respect of the application. Whether you want to prevent overheating or save heating energy, a different choice of the melting tem­perature is necessary.

As an example we simulated the thermal performance of a typical lightweight office. Important is the possibility of discharging the storage at night, therefore a night ventila­tion was modelled (ac/h=4). During daytime, only the minimum needed air-change-rate of ac/h=1 was assumed and no active cooling device is installed.

without PCM————————

The PCM was modelled with a melting temperature of 25°C with a melting range of 2 K, mixed to interior plaster. Fig. 3 shows clearly, how the temperature of the PCM-walls starts

rising slower at the beginning of the melting range (24°C-26°C). The stored latent heat is released during night, then leading to higher wall temperatures. In addition to the energy savings by the reduced cooling load, the lower surface temperatures of the walls result in an increased room comfort (Fig. 4). Under certain conditions, an active cooling device may be even unnecessary.

For the heating case, this effect of smoothing the peaks in wall and room temperatures is reachable too. But only for the transitional time in spring and fall there is enough surplus of heat to store in the PCM to expect, so that the overall energy saving for heating isn’t to big.