What is COP and EER?

[edit] What is COP and EER?

The Coefficient of Performance (COP) and Energy Efficiency Ratio (EER) are measures of a heat pump or heating and cooling solution’s efficiency. They indicate a ratio of useful heating or cooling produced by the unit against the energy it consumes. For example, the COP of a heat pump that can provide 3kW of heat against the input of 1kW of electricity is 3. The EER that generates a cooling effect of 12BTU against the input of 1kW of electricity is 12.

[edit] Can COP and EER be used to establish the overall energy efficiency of a heating or cooling unit

In simple terms, the higher the COP or EER, the more energy efficient the heat pump is. This is helpful as a relatively simple efficiency qualifier calculated as a punctual value at a given condition. As we know, however, the energy efficiency of heat pumps can change based on many factors, including for example variations in external temperatures, such as those from seasons.

The load requirement for heat pumps also changes, especially in temperate climates such as the UK. The Seasonal Coefficient of Performance (SCOP) and Seasonal Energy Efficiency Ratio (SEER) consider the energy efficiency of a heat pump throughout the entire heating and cooling season, providing a more accurate comparison of likely installed performance than COP.

SCOP can be calculated for more complex multi-unit solutions too, giving an important performance indicator for HVAC systems such as communal ambient loops that utilise in-apartment water source heat pumps and air source heat pumps as central plants. You can read more on the impact of SCOP of central plants on the energy efficiency of communal ambient loops here.

[edit] What do COP and EER tell us about carbon emissions?

When used with the Carbon Emissions Factor (CEF), COP and EER can be used to derive the carbon emissions produced by a heat pump. This is relevant in the context of compliance with the anticipated uplifted Part L.

When introduced, SAP10 will reduce the CEF of electricity by more than half, from 0.519 CO2/kWh to 0.233 CO2/kWh. Adjustments made to other fuels will be negligible. This means that to achieve the expected carbon reductions indicated by the Future Homes Standard, heat pumps are likely to become the default technology.

See also: Coefficient of performance and Seasonal energy efficiency ratio.

[edit] Related articles on Designing Buildings

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• Coefficient of performance.
• Combined heat and power CHP.
• Domestic heat pumps and the electricity supply system.
• Earth-to-air heat exchangers.
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• Ground source heat pumps.
• Heat exchanger.
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• Residential heat pump installations: the role of vocational education and training.
• Seasonal energy efficiency ratio.
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• Types of domestic boiler.
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• Water source heat pumps.