Cooling systems
The control of the environmental conditions for buildings directly impacts the performance of the occupants of the space. The most suitable cooling system applied in every case is being determined by variables like the size of the building, the building functionality (hospital, office, museum, warehouse, etc.), location, etc.
The main cooling system categories are:
1. Natural Ventilation
a. Cross ventilation -- This method depends on the movement of air through the space to equalise the pressure. Thus building shape is crucial in creating the wind pressures that will efficiently drive air flow through its apertures.
b. Stack/Displacement ventilation -- This method depends on the difference in air temperature to provide air movement in the cooling space. Displacement vents have been traditionally located at or near floor level. More suitable for high ceiling buildings (over 8ft). Natural ventilation works better in climates with cool nights and regular breezes.

2. Evaporative cooling -- An alternative to air-conditioning with low energy costs since no compressor is needed, only a fan and a water pump. This method is efficient for low humidity, dry climates. Evaporative cooling can be either direct or indirect. Direct cooling involves the water being exposed to an air stream. Indirect requires some type of heat exchanger.
3. Air Conditioning -- Fully mechanically operating systems maintaning specific conditions of temperature, relative humidity, providing proper circulation of air and low dust levels in an enclosed space. The working fluid can be a cooling fluid that absorbs the heating loads from the space by using the vapor compression refrigeration cycle. Alternatively hydronic piping distribution can be used. In this case the water (cooled centrally by a chiller) becomes the medium that absorbs all heating loads and cools the space. The next chapter details the most important categories.
4. Geo-exchange -- Utilises the earth (or a pond or lake) and the near-constant ground temperature to cool the space. Heat is drawn from the home and absorbed by the earth (heat sink). Components of this system include a ground source heat pump, a hydronic pump, a ground heat exchanger, and a distribution system. Most geoexchange systems utilise air ducting for the distribution system, and polyethylene piping in the earth for the heat exchanger. Main advantage is that can be used year round for both heating and cooling, as well as for hot service water .