Environmentally friendly cooling systems using photovoltaic electricity
The use of natural phenomena powered by renewable electricity from photovoltaic systems can provide excellent cooling for buildings in hot Mediterranean climates. Such natural phenomena include: the temperature difference between the inside and outside of a building during the summer, the fact that the temperature in the ground at a depth of about 2 metres is almost constant throughout the year at 18 degrees Celsius, and the fact that hot air becomes cooler when in contact with water. Using the first phenomenon; simple ventilation of the building at night, either naturally or mechanically, stores the cooling inside the building structure. Using electric fans running on solar electricity provides mechanical ventilation during the day. The power for these fans is generated from photovoltaic panels. Natural ventilation is also possible from window openings. The second phenomenon is that of natural ground temperature. Two meters below the earth's surface, temperatures remain at a constant 18 degrees Celsius throughout the year. Thus passing hot, ambient air through underground tubing systems cools the air sufficiently (up to 20 degrees Celsius depending on the temperature of the ambient air) so that when re-entering the building, it can serve to decrease room temperatures significantly. The third principle is based on an evaporation cooler system in which ambient air is run through cooler water and then re-pumped into the building. Two variations of this system exist, one is a direct method (water based) the other is an indirect method that is air-to-air based. For both methods, power is required to drive a pump and/or a fan, using, a PV panel to provide the energy for it and can be applied to water sufficient regions. Apart from their ability to provide comfort levels, the design, testing and comparison between such systems proved economic and reliable when carefully applied.
