Passive Solar Air Conditioning
For passive solar air conditioning, no mechanical and electrical devices are used. Instead, solar building designs or passive houses are constructed in a way that slows down the rate of heat transfer into the building during summer or out of the building during winter as type of solar cooling. Walls, floors and windows are designed to collect, store and distribute the heat of the sun and serve as passive solar air conditioners.
It is difficult to adapt passive solar air conditioning in already existing constructions. New constructions with a passive energy design need little or no extra energy to cover their energy needs. Still passive houses have energy needs, which are usually covered by solar panels.
Active Solar Air Conditioning
Photovoltaic solar air conditioning is the most implemented solar cooling technology for residential and smaller commercial projects. With photovoltaics every type of electrically powered air cooling is possible, i.e. with a conventional compressor or based on absorption. Solar air conditioning with compressors is most common, but less efficient than other forms of electrical cooling systems.
Other active solar air conditioning systems use solar thermal collectors. The generated energy can be used to drive adsorption or absorption chillers. This type of solar air conditioner can have single, double or triple iterative absorption solar cooling cycles - the more cycles it has, the more efficient it is.
Geothermal Solar Cooling
A geothermal pump or solar cooling tube can also be used for solar air conditioning. It leads cool air out of the earth ambiance into a building. For a geothermal pump the cooling option increases construction costs, but reduces or eliminates the costs for conventional solar air conditioning.