Dynamic analysis of building hygrothermal behavior

We describe a mathematical model applied to analysis of hygrothermal behavior of buildings. A lumped approach to model the room air temperature and humidity is used and a multi-layer model in finite differences for the building envelope  is  employed. The capacitance model allows studying the transient air humidity and temperature of a room when it is submitted to the weather of the city of Curitiba-PR, Brazil. To evaluate the building performance with thermal parameters, we have written a code which includes air infiltration, conduction loads, internal gains of people, lights and equipment and short and long wave radiation. In the results section, we show the influences of simulation time step on internal temperature  and  humidity  and  temperature  profiles within the building envelope.