Analysis of numerical methods and simulation time step effects on the prediction of building thermal performance

A mathematical model applied to the analysis of hygrothermal behavior of buildings is described in this paper. A lumped capacitive and transient approach to model the room air temperature and humidity is described. To evaluate the whole building performance, it was employed a multi-layer model in finite differences for the building envelope and, in this code, we can include air infiltration, conduction loads, internal gains of people, lights and equipment and short and long-wave radiation. Different numerical methods are used to integrate the differential governing equations in the air domain, and results in terms of accuracy and computer run time are discussed in the paper. In the results section, we also show the influences of simulation time step on both room air temperature and humidity and temperature profiles within the building envelope.