Renewable energy for air conditioning: Aerothermal energy

Previously I have been talking about the different renewable energies. Geothermal energy, biomass, etc. However, there are other sources of renewable energy that are not as widespread since their use is rather local and for small places like the home.

In this case let's talk about aerothermal. What is aerothermal energy, how does it work, advantages it offers us and its performance.

What is aerothermal?

I mentioned that aerothermy is a type of renewable energy since it is practically infinite and to produce it, we only need approximately ¼ of electricity. It is about taking advantage of the energy contained in the outside air, to heat the interior through the use of a high-efficiency heat pump.

A heat pump works by extracting energy from one place to give it to another. In order to do this, you need an outdoor unit and one or more indoor units. The energy contained in the air in a natural way can be used in an inexhaustible way since it is presented in the form of temperature. If we extract the heat from the air, the sun will heat it up again, so we can say that it is an inexhaustible source.

The energy contained in the air in a natural way, in the form of temperature, is available in a virtually inexhaustible way, since it is capable of regeneration by natural means (heating by the energy of the sun), so that aerothermal energy can be considered as a renewable energy . Using this energy it is possible to produce heat and hot water in a less polluting way, achieving energy savings of up to 75%.

How does aerothermal work?

It is normally used for air conditioning or air conditioning. To do this, we use the heat pump. This is responsible for heating or cooling the air in the premises. It works thanks to a heat pump of the air-water system type that what it does is extract the heat that exists from the outside air (this air contains energy) and transfers it to the water. This water provides the heating system with the heat to heat the premises. Hot water is also used for sanitary purposes.

Heat pumps usually have a fairly high performance and efficiency close to 75%. Even in winter it can be used in very low temperatures with little loss of efficiency. How can you get warmth from cold air in winter? This is a question people often ask themselves when they hear about the aerothermal. However, this happens thanks to heat pumps. Oddly enough, the air, even at very low temperatures, it contains energy in the form of heat. This energy is absorbed by a refrigerant that circulates inside the heat pump, between the outdoor and indoor units.

In general, the outdoor unit acts as the evaporator in winter and the indoor unit is responsible for being the condenser that transfers the heat to the water in the heating circuit. When it comes to cooling instead of heating, it's the other way around

Where is aerothermal used?

Aerothermal systems are designed to be used in small places. Although it has a great efficiency and performance, the calorific value is not much as to heat large areas. They are typically manufactured for use in single-family homes, some very small buildings, for premises, etc.

Aerothermal efficiency and points to take into account in its installation

When it comes to talking about energy efficiency, we talk about the COP (Coefficient of Performance). In Spanish it is called the coefficient of operation. Normally, heat pumps used for aerothermal energy have a COP of around 4 or 5, depending on the manufacturer. What does this mean? That for each kW-h of electricity consumed, the aerothermal equipment can produce in optimal operating conditions 5 kW-h thermal.

Systems are guaranteed to work up to -20ºC. In the event that they cannot provide the correct temperature, they integrate an automatic support equipment. There is also equipment on the market that can work in combination with boilers, generally condensing.

Although I mentioned earlier that even in winter, heat pumps are capable of extracting energy and heat from outside air, they are designed for temperate climates. In other words, the lower the outside temperature, the more performance the heat pump loses. Currently they work from -20º C generally.

The most important points to take into account so that the efficiency of the aerothermal systems is as high as possible are:

• Higher initial investment compared to a conventional system
• Outdoor unit location (aesthetics, noise ..)
• In very cold climatic zones, the seasonal yield is reduced, so it is advisable to carry out an in-depth economic study.
• The convenient thing is to have a low temperature heating system, such as underfloor heating or efficient radiators.

Advantages of using aerothermal energy

We have to take into account that aerothermal energy uses energy from the air, so it is renewable and free. What's more we can have it 24 hours a day. We analyze and list its advantages:

1. The maintenance cost is lower than that of other traditional systems. Because heat pumps do not have a burner or combustion chamber, they do not generate waste and do not require cleaning.
2. Installation is simple as it does not require an area to store the fuel.
3. As it does not require any type of flue gas evacuation duct, it does not require any chimney on the façade or on the roof.
4. Contributes to home security by not storing fuel.
5. It has a lower dependence on fossil fuels so it has a very low contribution to the increase of the greenhouse effect and climate change.
6. Its performance is usually quite high.
7. As there is no combustion in aerothermal equipment, water vapors are not produced that can cause condensation and damage to the equipment. For this reason, not only is there no return temperature limit, but it is recommended that aerothermal equipment work at the lower the better, since in this way its performance (COP) increases rapidly.

As you can see, aerothermal energy is another good source of renewable energy that, like biomass boilers and other conventional ones, can air-condition homes and small buildings in an environmentally healthy way.