When sizing a heat pump for both heating and cooling, what is primarily used for sizing?

Sizing a heat pump for both heating and cooling primarily uses the cooling load as it generally dictates the capacity required to maintain comfort during warmer months. The cooling load calculation accounts for heat gain from various sources, such as solar radiation, internal heat from appliances, occupants, and the physical characteristics of the building.

This is especially important because heat pumps often operate more efficiently and effectively when they are sized to meet the cooling demand. If a heat pump is undersized for cooling, it will struggle to remove sufficient heat from the indoor environment, leading to discomfort and reduced efficiency.

While heating load and factors like heat loss and outdoor temperature are also critical considerations, they typically serve as secondary criteria in the overall sizing process. The cooling load often takes precedence, particularly in climates where cooling is required more intensively than heating.