The COP, coefficient of performance, is defined by the ratio between the instantaneous heat power produced by an energy system and the instantaneous electrical power consumed. 

For heat pumps, it is a theoretical performance indicator estimated under constant condensation and evaporation temperature conditions. 

In particular, it makes it possible to compare heat pumps with each other for the same operating conditions. 

It does not take into account temperature variations and therefore cannot present in any way the annual performance of an energy system.

In the case of a Water Glycole/Water heat pump, it is presented as follows: 

COP B0/W35 = 4,3

Where B designates the Brine, the heat transfer fluid traveling through the cold primary circuit of the heat pump, followed by the evaporation temperature (0°C in this example).

IN designates the Water, the water traveling through the hot secondary circuit of the heat pump, followed by the condensation temperature of the heat pump (35°C in this example).

A COP of 4 means that the heat pump compressor needs to consume 1 kW of electrical energy to produce 4 kW of thermal energy.

The SCOP, Seasonal Coefficient Of Performance, is defined by the average of theoretical COP over a complete season (or a year) by taking into account the variation in the evaporation temperature due to the outside temperature of a specific location. 

The SCOP is generally calculated for a constant condensing temperature (hot side), which depends on both the heat distribution systems and the comfort level linked to the different services to which the energy system must respond. It is therefore more realistic than the COP for presenting the performance of an energy system, but remains a theoretical approximation. 

The SCOP makes it possible to determine the energy class of the thermal system.

In the case of a Water Glycolated/Water heat pump, it is presented as follows: 

SCOP W35 = 5.0

SCOP W55 = 3,74

Where W designates the water traveling through the hot circuit of the heat pump, followed by the condensation temperature (35°C and 55°C in this example).

The example shows that the performance of the heat pump deteriorates when the hot setpoint temperature is higher.

SPF, seasonal performance factor, is an actually measured or numerically simulated index of an energy system over a complete season (or year).

This is the ratio between the amount of thermal energy produced by the system and the amount of energy consumed to produce this heat. 

It takes into account the real variations in conditions linked to the operation of the system and integrates the energy consumption of all ancillary components (water pumps, ventilation, etc.). It thus presents what the heat pump will actually consume to meet the thermal needs of a building. 

A facility's solar thermal coverage rate, also known as solar capture rate or solar capture efficiency, is a measurement of the efficiency with which a solar thermal system captures and uses solar energy to heat a fluid or produce heat. It is expressed as a percentage and represents the fraction of incident solar energy which is actually captured and transformed into useful heat by the system.

The norm norm NF EN ISO 9488 defined this rate with this calculation formula: 

Tcouverture = Qsu / Qecs

Qsu= Useful heat production at the tank outlet 

Qecs = Heat withdrawn

In other words, the solar thermal coverage rate indicates the extent to which a system is capable of harnessing solar energy to meet its heating or hot water production needs. A high solar thermal coverage rate means that the system is very efficient in relation to the needs of the installation, while a lower rate indicates poorer performance.

The energy saving rate is the difference in consumption of paid final energy (electricity, gas or other) between a solution with solar energy contribution and a solution without solar energy contribution, compared to consumption without solar.

It is calculated as follows: 

Energy saving ratej = 1 – Eas/Ess

Eas = Final energy consumed with solar contribution
Ess = Final energy consumed without solar assistance

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