Helps size any system for heating and air conditioning of a building, i.e., the terminal units, the zone units and the total capacity of the cooling or heating plants. DPClima performs a 24 hour calculation of the steady state value of the cooling and heating loads of a building for a typical day of each month (either the coldest or the hottest). DPClima organizes the spaces into several zones inside the building so that the designer is able to adapt its system best to the thermal response of those zones. The calculations are done using the heat transfer functions methodology. Inside the spaces schedules are defined for; occupancy, lights and other loads. A database is distributed with information about types of walls, glasses, human activities, type of lights, etc.