2 Ton Mini Split Reviews. The Coefficient of Performance (COP).

Energy is needed to activate the heat pump cycle and to compress the vapour for the production of useful heat. The efficiency of this process is expressed by the ratio between the useful heat delivered by the condenser and the driving energy used by the compressor. This ratio is called the Coefficient of Performance (COP).

As environmental heat is free and available in very large quantities, it is not included in the COP. That is why the COP is bigger than 1. The COP of the current generation of heat pumps varies from 2.5 to 5. Since the COP shows performance at a steady state only, a second parameter is usually used to show the performance of the heat pump over an entire year which is the ratio of annually delivered useful heat over annually used driving energy. When calculating the SPF, it is common to include the annual electricity requirements of auxiliary equipment, such as circulation pumps, fans, etc.

The climate (annual heating and cooling demand and peak loads); The temperature of the heat source and the heating distribution system; The auxiliary energy consumption; The heat pump control. The performance of electrical heat pumps should be balanced by the fact that the efficiency of electricity generation  is less than 40%. That means that for every unit of electricity used, more than 2.5 units of primary energy (mix of oil, gas, peat, etc.) have been burned. Therefore, a heat pump with a COP of 4 driven by electricity generated by a thermal power plant has a primary energy efficiency of 160%. 

 

That is already better than the 100% achieved by a modern gas condensing boiler operating at low temperature for example. But you can increase the primary energy efficiency of your heat pump, and therefore its environmental benefit, by 3 times by driving it with green electricity. It is now possible to switch easily to a green electricity supplier at no extra cost (see the REIO fact sheet on green electricity).