SOLAR PASSIVE ARCHITECTURE

Passive, a term frequently used in energy-efficient concepts, basically refers to the architecture in which energy is induced to flow from one living space to another by means of natural principles of heat flow. These techniques manifest themselves best in traditional

dwellings that have withstood the test of time…..in terms of material-use, spatial distribution, construction technology, orientation etc. Solar Passive designs involve methods of collecting, storing, distributing and controlling thermal energy flow by natural means as opposed to the ‘active’ methods of employing mechanical devices to achieve thermal comfort.

Passive solar architecture is energy efficient and sustainable. It minimizes the impact of the building to its immediate environment and efficiently utilizes the on-site energies and available natural resources, thus becoming an influential player of the macroclimatic-system. A building cannot be treated as a mere fuel-guzzling machine but should be regarded as a biological being living in its eco-system. It should breathe in and exhale out, consume and release energy into the environment without causing harm or imbalance in the natural structure of the macro-climate. This can only be attained by implementing techniques that we can learn from the natural world. Man has to obey the laws of nature.

Passive design is simple and involves techniques such as building orientation, direct-indirect heat gain, proper use of materials, colour and texture of building envelope, shading, vegetation etc. By judiciously using scientific design tools relevant to the climatic context one can maintain steady and comfortable conditions within the building environment. This reduces the amount of energy that would otherwise require running active devices to attain similar levels of comfort. At times these simple techniques seem to be ineffective and advanced techniques of passive design need to be incorporated such as trombe wall, solar chimney, roof ponds, wind towers, earth-air tunnel etc.

Rammed Earth systems in the Himalayas, Sun-baked Earth Brick construction in the Kathmandu valley, Wattle and Dough of the terai are standing examples of Passive solar designs. All of these traditional systems characteristic of the different geographic regions of Nepal employ the use of natural materials and heavily rely on building orientation for heat gain. In the Himalayas, dwellings are always constructed on south-facing slopes for heat gain and are closely built to reduce wind flow.  In the valley, thick sun-dried brick walls serve as thermal mass and radiate heat into internal spaces at night-time. The terai huts are built out of locally available materials which are generally by-products of food crops, vegetation is used for shading and evaporative cooling is employed in the internal spaces.

Traditional dwellings generally employ simple techniques of passive solar design and vividly demonstrate the effects these simple tools have in the habitable environment. With necessary amendments these techniques can be used in modern structures to increase their thermal performance.