The first step of an energy model, and sometimes the only step is the Load Calculation. The load calculation is used to determine the amount of heating and cooling required as well as the total airflow required.

The load calculation is the process of determining the heating and cooling requirements of a building based on factors such as the size of the building, the number of occupants, and the climate.

The Load is often expressed in units of Tons. Heating is sometimes defined in Therms/hr or MBH. Alternately, units of KW are used.

It should be noted that all of these values are units of power and are therefore interchangeable. See Energy-models.com/Tools for more information on converting