Hot water is more than just comfort. For most Westerners, hot water is part of everyday life and is one of those things you can’t imagine doing without.
Hot water can be produced using heat pumps, but it is now possible and necessary to consider heating water in the most environmentally friendly way possible: for example, with the help of solar heating systems.
It is also possible and desirable, in order to reduce costs and emissions, to use hot water sparingly.
The rational use of water is very important, especially when it comes to the environment: water is becoming an increasingly scarce resource.
The heat pump is a thermodynamic device that recovers the heat contained in the air, earth or water, elements present in nature, to transfer it, via transformations of a refrigerant fluid, inside a dwelling in order to heat it and sometimes produce domestic hot water.
On average, a person uses between 40 and 60 litres of hot water (between 40 and 60 °C) every day. Taking daily baths easily multiplies energy consumption by two or three.
Hot water is produced centrally or decentrally. In buildings, water is usually heated in a large water heater and distributed to all outlets. Everyone uses this hot water according to their desires and needs, with energy costs shared equitably between each inhabitant.
The major disadvantage of this type of installation is the loss of heat due to the length of the pipes. In the case of decentralized systems, the water heaters are installed directly in the apartments. Hot water is thus produced at the place where it will be consumed. The heat losses are much lower and the hot water consumption can be calculated individually.
The water can be heated or preheated using a solar thermal system. Ideal for this type of installation is either a flat roof or a sloping roof, facing south, southwest or southeast.
An area of 4 to 6 m² of collectors is sufficient to cover the annual hot water energy needs of a family of 4 people.
The rest of the energy must come from another source, such as a heat pump. Solar thermal systems are very simple to install. Moreover, it is rare to have to apply for a building permit, a declaration to the municipality is sufficient.
The advantage of a solar thermal system is obvious: it is clean energy. Moreover, these systems do not require any maintenance and can also be used as a heating supplement.