The program CASAnova – An educational software for heating and cooling energy demand as well as the temperature behaviour in buildings can be used intuitively in order to understand the relations between building geometry, orientation, thermal insulation, glazing, solar heat gains, heating demand, heating and primary energy as well as overheating in summer.
The user of CASAnova can adjust and change more than 20 different parameters. All inputs in CASAnova are made with the mouse; to do this scrollbars and listboxes are at the user’s disposal. Calculations take place immediately after the modification of a parameter and results are immediately shown in the diagrams and the tables.
The calculation of heating demand is based on the European norm EN 832. CASAnova uses building shapes of rectangular form for which in a monthly balance transmission and ventilation losses as well as solar and internal gains are calculated. Heating demand is the difference between energy losses and energy gains of the building.
For determining the number of hours which are overheated in the considered building CASAnova uses a single-zone dynamical thermal model. Based on hourly data of the outside temperature and the solar heat gains through windows and walls, CASAnova calculates the useable solar heat gain as well as the transmission and ventilation losses of this zone. Together with the internal gains the balance of energy for an effective thermal mass is determined (i.e. energy losses and gains for the room-air including the heat which is stored up in an active part of the wall). According to the amount and the sign of this balance zone temperatures change with time. Finally, the number of hours is counted for which room-air temperatures exceed a comfort temperature limit given by the user.