The dynamic simulation of the heat transfer between buildings and their environment is situdied through the software TRNSYS. First, a very simple building is considered and the energy demand for heating evaluated through TRNSYS is compared with that obtained by apllying the Italian Standard UNI TS 11300-1:2008. This excersise has the purpose of verifying the correct use of the simulation program. Then, the annual energy demand for heating, cooling and humidity control, with reference to a well insulated one-family house, under construction in a country location near Bologna, is evaluated through TRSYS. The building has a wood frame and wooden insulation. First, plots of the internal air temperature of each climatic zone in the absents of the plant operation are obtained. Then, the monthly energy needs to ensure acceptable conditions of the internal air temperature and humidity are evaluated, both in the absence and in the presence of a heat recovery system.

Outgoing