Application Guidance: Air-source Heat Pumps
The products listed on this website provide central heating and cooling through a ducted system controlled by a thermostat (for smaller spaces without ducts, a mini-split heat pump, which is installed directly in the space, may be a good solution). Due to the complexity of ASHP systems, and building code requirements for HVAC safety and efficacy, an accredited mechanical contractor or engineer should be consulted to fully define the system specifications prior to purchase.
A key input provided by the contractor is the total capacity required to heat and cool the space. Maximum electricity power draw increases approximately linearly with capacity. In the data presented here, capacity and energy-use numbers are scaled to values per square foot (sq-ft) of conditioned space. After selecting the appropriate climate zone and building type for your installation, a rough estimate of the necessary capacity can be obtained by multiplying the capacity per sq-ft by the area of the conditioned space.
In considering higher efficiency models, the main consideration is the expected annual hours of operation. Higher operating hours for a given capacity ASHP mean higher energy costs, and therefore more value to be gained from efficiency. For a given climate, higher operating hours correlate with high occupancy or long hours of building operation. These effects can be explored by looking at the data provided here for different building types in a fixed location. The impact of climate on capacity and energy use can be evaluated by looking at data across multiple climates for a given building type.