Depending upon the location, the nature of the building, residential or commercial, renewable energy sources of appropriate origin can be employed (EERE, 2005).
One of the major reasons for power consumption in buildings is for heating and cooling the buildings (EST, 2006). This consumes almost 42% of the energy consumed by the entire building. If this could be brought under the energy optimisation and under renewable energy portfolio, it could result in immense savings for the buildings. A solar powered energy source is one of the renewable sources that are adopted. Solar energy is a constant and free for use source that is available during the day time and has to be stored to make use of during the night. This is accomplished using two methods of solar energy tapping. One, solar energy is trapped as heat and is used to heat the house or building and it is insulated in such a way that it continues to maintain the warmth in the house through out the day and the night. Secondly, solar energy is also converted into electric energy using the solar photo voltaic cells. This gets saved in the batteries are is directly employed to run the equipments for heating and cooling like the HVAC systems in association with the regular power supply.
Transpired solar collectors are used to collect solar heat. These are normally dark, perforated metal wall that would collect almost 80% of the solar heat that falls over it. This is then used to heat the air draught that would provide needed heat for ventilation of the building. Two methodologies are adopted in using the heat collected in the solar collectors. The draught of air gets heated up during the course of the day and continues to heat the entire building as it continues through the night. The other method, heats the water to a high degree from which the heat is distributed through the regular heating lines in the building. Both the methods are used at different locations depending on the convenience.
Solar Photo Voltaic Cells
Solar panels are extensively used in environmentally friendly buildings to collect the heat of the sun and convert it directly into electricity to enable employing it effectively in all the spheres of work. This has been done extensively in many locations, as roof fitted photo panel; also as separate panels that would help in augmenting the electricity consumption exercises.
Ground Source heat pumps
These are normally pipes or bores dug into the ground to depths of about 200 to 300 feet is sunk and the additional heat is pumped into the ground during summer and taken off later during the winter when heating is needed. These ground source heat pumps are effectively employed in some of the locations in US and in the rest of the world. It has been repeatedly found that the ground source heat pumps are efficient in pumping in and out the energy, contain it for a period of time and can be used as a large storage space for energy (EST, 2006). These are specifically suited in locations where there is a cooling requirement in the summer and a heating requirement in the winter.
Small Scale hydro
These are made to use the potential energy of stored water. Water that has accumulated certain potential energy