The installers are formal: the successful installation of a heat pump that is to say, which will provide optimal comfort for the occupants and generate significant savings on the heating bill – is closely linked to four essential criteria. Namely, these are sizing, COP or coefficient of performance, consumption, and performance.
Thermal Study, The Prerequisite
For the sizing to be of quality there is an essential prerequisite. The installer must carry out a thermal study to assess the losses of the house. The said study is compulsory in new buildings to obtain an RT2012 building permit.
This assessment will make it possible to determine the calorific needs of the dwelling precisely. But beware this must be done in the rules of the art, that is to say by a professional! It is a critical element in the proper sizing of your heat pump.
Likewise, in the case of a heat pump that provides both heating and domestic hot water, the installer will also have to assess the local hot water requirements, the thermal study not taking it into account.
Sizing, The Decisive Phase
Once this assessment has been made, to calculate the dimensioning of a heat pump, the thermal power required for the home must be evaluated. This step is managed by calculation software. Thus for an air-water heat pump, various data are compared graphically, such as the calorific power of the device and the outside temperature. This software will also integrate multiple parameters, including the heat losses highlighted. Among other characteristics that will be taken into account, the area and height of the rooms in the house, the type of emitters convectors, heated floors, etc., the climatic zone concerned as well as the average annual temperature. Without forgetting, if the project is a renovation, the habits of thermal energy consumption.
You should know that the wrong sizing of a heat pump is not without consequences. Thus an over-sizing of the power compared to the real needs can result in an additional cost on a purchase, but also installation costs overconsumption of electricity by multiplying on or off cycles and loss of performance and shorter life due to jolts. The undersized will mean more frequent use of auxiliary heating and a reduction in energy savings.
A successful dimensioning, that is to say with a power adapted to the needs, is, therefore, the sine qua none condition to reduce consumption.
Electricity Consumption: The Key To Savings
The installer must also estimate the electrical energy consumption of a heat pump. A problematic exercise insofar as it depends, in addition to the correct sizing, of numerous parameters, often independent of the heat pump itself. The following are taken into account:
The nature of the construction: the better the insulation, the lower the requirements, the less the heat pump will consume.
The geographical area: it is evident that the milder the climate, the less the heat pump consumes electricity to provide the same calorific power.
The nature of the installation: as a boiler backup, with or without electric backup, with domestic hot water or not, etc.
Whatever the configuration, the type of installation or the type of material, heat pumps ensure, in the long term, a significant reduction in the energy consumption of the home. They would thus be 2 to 3 times lower than with electric heaters. It is accepted that a heat pump, under ideal installation conditions, can reduce consumption by up to 60%.
According to the installers, who specialize in installing heat pumps, an intelligent regulation system will make it possible to take advantage of the characteristics of the installation and therefore to further reduce consumption, by 10 to 25% compared to a facility without regulation.
Mandatory since September 2015, the energy label is an excellent way to quickly find out about the consumption levels of a heat pump. If we compare them to other heating methods, they are positioned at the top of the label scale: A + and A ++ for Air or Water systems and up to A +++ for geothermal heat pumps.
What Coefficient of Performance?
Measured under standardized test conditions (EN14511), the COP, or coefficient of performance, of a heat pump quantifies the efficiency of the different heat pumps. It makes it possible to compare their performance. It represents the relationship between the electrical energy consumed and the thermal energy produced. According to our installers, the ratio is variable depending on the temperature difference between the energy source water, air or soil and that used in the heating or hot water production device. It reflects the possible performance of a heat pump. The value of the coefficient of performance indicated is the maximum value given at an ideal outside temperature of + 7 ° C. This means that in the event of negative outside temperature, the COP drops.
An efficient heat pump generates energy savings if its coefficient of performance is greater than 3. A COP is equal to 3 means that the heat pump consumes 1 kWh of electricity and releases 3 kWh of heat. The thermal energy returned for heating is, therefore, three times greater than the electrical energy consumed.
The Heat Pump Provides More Energy Than It Consumes.
More concretely, more than 60% of the production of heat or hot water supplied by the heat pump is of renewable origin. The minimum value of 3 takes into account the average efficiency of a power plant, which is around 33%. This means that you need to consume 3-kilowatt hours (kWh) of primary energy to produce 1 kWh of electricity. The installer will, therefore, confirm that the heat pump must thus generate 3 kWh (in the form of heat) for 1 kWh of electricity consumed.
The smaller the difference between the temperature of the heat source used and that of the heat pump outlet, the higher the coefficient of performance and therefore, the more efficient the device. The COP will consequently be more senior with the Water or Water heat pumps which use a hotter source, namely water captured in the ground, more stable in temperature. A soft heat heater, such as a heated floor, can also optimize the coefficient of performance.
For heat pump installers, the average annual coefficient of performance is a good indicator that takes into account the yearly climatic conditions. As a general rule, the latter advises that it is better to choose NF PAC systems with a performance coefficient of at least 3.5.
Note that some heat pumps have a performance coefficient greater than 5, thanks in particular to variable speed compressors which limit electricity consumption.
Yields and Variations
By diffusing more energy than they consume, heat pumps offer efficiencies that generate 50 to 60% energy savings compared to conventional heating systems.
According to our installers, the performance of a heat pump is given by the coefficient of performance or COP specific to each model. Concretely, the COP is, on average, between 3 and 5, which means that for 1 kWh of electricity absorbed, the efficiency of a heat pump is between 3 and 5 kWh. For example, for 6000 watts consumed to operate the heat pump and heat the house, its electrical consumption will be only 2000 watts.