Appropriate Technology Asia

Passive Solar Architecture

There are two basic approaches to the utilisation of solar energy in buildings - active systems and passive systems. Active systems are generally those that are very visible with collectors on roofs, pumps, plumbing, control systems and storage tanks - in other words, systems that are expensive to finance and which may be difficult to maintain.

Passive systems are defined as those where the heat moves by natural means. Passive Solar technology uses sunlight to provide a renewable source of energy for space heating. The technology works in three stages: the collection of solar energy; the storage of the heat collected; and the subsequent release of this heat in a useful way. The realisation of these three aims depends on understanding and exploiting a number of physical factors. These include: the convection properties of the air within the building, the absorption qualities of dark colours and building materials, the heat storage properties of these building materials; and the poor heat conductivity of insulating materials.

Taking these factors into account during the design of the building can allow the heating needs of the occupants to be fulfilled by solar radiation at no cost. Because the cold winters are characterised by low rainfall and clear skies, passive solar technology is ideally suited to the areas where ATA works and provides an important means of improving local housing.