There was a time when customers never asked about the COP and SPF rating of their heat pump, but they do now. Both ratings are an important consideration when choosing the right heat pump for your home. Heat pumps are powered by electricity but unlike conventional electrical heating, a heat pump is highly efficient. If you are looking into heat pumps, you’ll have come across the terms COP and SPF. So here is a quick breakdown:
Coefficient of Performance (COP)
COP (Coefficient of Performance) is a measure of efficiency. The efficiency of any machine or system can be calculated at the ratio of the amount of work done by a machine to the amount of work given to the machine. In the case of a heat pump, its efficiency is the ratio of useful heat energy produced to electrical energy consumption. A COP of 2.5 means that the heat pump supplies 2.5 times as much heat energy to the system as it consumes in electrical energy. The answer here is that COP measures how efficient a heat pump is at turning electrical energy into usable heat. It doesn’t do this by creating energy or being more than 100% efficient. It does it by using heat energy in the outside air, ground, or water.
Seasonal Performance Factor (SPF)
Where COP gives us the efficiency of a heat pump at any given time, SPF gives us the same but for the annual performance of the heat pump. The heat pump needs to raise the temperature of this outside source to that needed by the heating system. The outside temperature is lower in winter and higher in summer, affecting the work the heat pump needs to do. the lower outside temperatures the heat pump will need more electrical energy to produce a given heat output, meaning that the system is less efficient. As a result, the COP will be different through the seasons and SPF encompasses this by considering the system's annual performance.
Are both ratings important?
They both have their merits however, the COP factor gives you an instant measure to determine how well your heat pump is performing. It is worth however noting that two similar heat pumps in the same house can have different COP and SPF ratings depending on how they have been designed and commissioned. That is why it is so important that your heat pump is well designed and commissioned as 1 degree difference in the flow temperature can make a 2.5% difference in your energy consumption.
