The major part of the energy of the air is nothing else than the solar energy that is released to the environment by the solar radiation passing through the atmosphere. That’s why the air can be rightly considered a renewable energy source.
The average air temperature is highly variable through the year and it also varies depending on the region because it is affected by the sun exposure, the intensity of the wind and other climatic factors.
By the way, even at cold temperatures (below 32°F and even lower), the heat content of the air is significant and it can be recovered and used for heating purposes.
Thanks to the air-source heat pump technology, it is possible to usefully get an advantage from this “hidden” energy. The heat pump is a device that moves renewable energy (heat) from one source at a lower temperature (outdoor air) to a sink in a different location (building) at a higher temperature using either thermal energy (gas absorption heat pumps) or mechanical work (electric heat pumps).
Therefore, in other words, an air-source heat pump can get energy from the environment (even if the temperature is very low) and move it to the heating system of the building.
Given the chemical and physical properties of the refrigerant flowing inside the heat pump, the refrigerant can evaporate at a lower temperature than the ambient, recovering (inside the evaporator) and “pumping” (inside the condenser) energy to a medium fluid (normally water) at a higher temperature.
The process can be normally reversed in order to provide either heating during winter or cooling during summer.
The performances of the heat pumps are measured in different ways and vary according to the technology used.
The electrical Air Source Heat Pumps (ASHP) use:
COP (Coefficient Of Performance) which is the ratio of the thermal capacity provided by unit to the work input;
HSPF (Heating Seasonal Performance Factor) which is the ratio of thermal energy delivered over the heating season (Btu) to the total electric used (Wh) to electrical energy input.
The Gas Absorption Heat Pumps (GAHP) use:
GUE (Gas Utilization Efficiency) which is the ratio of the useful thermal capacity provided by the unit (Btu/h) to the thermal input (Btu/h).
Robur Air Source Gas Absorption Heat Pumps are available in two different models: