What is the efficiency metric for heat pumps?

The Coefficient of Performance (COP) is the appropriate efficiency metric for heat pumps because it specifically measures the ratio of useful heating or cooling provided to the energy consumed by the heat pump system. The COP takes into account the energy output compared to the electrical energy input, providing a clear indication of how efficiently the heat pump operates under specific conditions.

This metric is particularly relevant for heat pumps as they transfer heat rather than generate it, allowing them to achieve efficiencies greater than 100%. A higher COP indicates a more efficient heat pump, meaning it can produce more heat energy than the electrical energy it consumes.

In contrast, the Energy Efficiency Ratio (EER) and Seasonal Energy Efficiency Ratio (SEER) are primarily used for air conditioning units to measure efficiency based on specific temperature conditions and typical operating cycles, respectively. The Annual Fuel Utilization Efficiency (AFUE) is a metric used for measuring the efficiency of combustion heating appliances, such as furnaces, rather than heat pumps, which do not rely on burning fuel. Hence, COP is the most relevant metric for assessing heat pump efficiency.