Passive Solar Energy
Passive solar energy is the use of solar power without any active mechanical devices to convert or act on the energy. This is opposed to the idea of active solar power systems which use solar panels to collect the sunlight and convert it into electricity. Generally passive solar designs do not require any conventionally generated or supplied power to run, however there are exceptions to this rule, where a small amount of power supplied by “normal” or conventional means is used to control aspects of the passive solar designed system. Passive solar power systems can be used to heat your home, heat your swimming pool, provide hot water for household use, and can even be used to ensure your home has good ventilation and air circulation.
There are also examples of bad passive solar design, in which rooms within a dwelling become very difficult to cool in summer and this can lead to inefficient use of power hungry air conditioner systems. Quite often, installing external shading or louvers can significantly improve the unwanted heating of a room by solar energy.
Adding thermal mass is often used to smooth out the highs and lows of temperature variation, so that a building can be cooler through the day and warmer at night. Practically this can be achieved in building design using some more traditional building materials such as stone or by adding thermal mass to the walls and/or flooring slab or support.
Solar chimneys can use convention to naturally move air by means of heating the air in an exposed chimney, which rises and in turn draws stale air up from a building below, and this technique can be very effective in ensuring air circulation without requiring electrically driven fans or other equipment.
Other uses of passive solar technology include solar cookers, which have solar reflective arrays or mirror systems to concentrate the sun's rays into a central area containing a cooking vessel. These have particular interest in remote or developing areas, where conventional electricity or gas or even wood supply for burning are just simply not available. More specialized uses of passive solar technology can include solar forges and concentrators for extreme heating of a small area. These require very careful alignment to achieve the necessary concentration of energy into a small central area.
In a truly modern energy efficient, green environmentally conscious building, there is a role for both passive and active solar energy systems. Good insulation, good building design principles and clever use of solar power panels and electricity generation schemes can all have a part to play in ensuring we reduce the reliance on conventionally generated power in our society.