Seasonal performance factor

Also known as SPF

Seasonal performance factor, or SPF, describes how efficiently a heat pump system is expected or measured to work over a season rather than at one test point.

Seasonal performance factor, or SPF, is a heat pump system efficiency measure for a season, typically a year. It compares the heat delivered by the heat pump heating system with the electrical energy consumed over the same period, so an SPF of 3 means about 3 kWh of heat for each 1 kWh of electricity in that seasonal calculation. In MCS heat pump paperwork, SPF may appear in a Heat Pump System Performance Estimate and can be used to turn annual space-heating demand into an estimated electricity figure. It is installation-specific rather than a single laboratory COP or a manufacturer SCOP rating, and it can be affected by heat loss, emitter choice, flow temperature, weather compensation, controls, hot-water treatment, weather and user behaviour. The calculation or monitoring boundary also matters because some figures include only the heat pump while others include associated pumps, supplementary heating or wider system loads. An SPF estimate should not be read as a guaranteed running-cost result, a full system design, proof of comfort or evidence that the heat pump has been sized correctly.