Passive design
is the key to sustainable building. It is a concept wherein the residence and the spaces within it
benefit from natural sunlight, ventilation and even temperatures. It achieves this by using free,
renewable sources of energy such as sun and wind to provide household heating,
cooling, ventilation and lighting, thereby reducing or removing the need for
mechanical heating or cooling.
It can also reduce energy use and
environmental impacts such as greenhouse gas emissions. Interest in passive
design has grown, particularly in the last decade or so, as part of a movement
towards more comfortable and resource-efficient buildings.
The key elements of passive design include
building location and orientation on the site, daylight, shading, thermal mass
and ventilation. Each of these elements works with others to achieve
comfortable temperatures and good indoor air quality.
Key features of passive design:
1. Location and
orientation of the building:
Orientation, layout and location on site will all influence the amount of sun a
building receives and therefore its year-round temperatures and comfort. It determines the solar energy in a home
where we allow sun in during cooler months to provide warmth, while keeping
summer sun out to prevent overheating.
2. Day-light: Should be used as much as possible to light a
home, both for energy efficiency and for the health and comfort of occupants.
3. Shading: Providing shade over building openings and
outdoor spaces can reduce temperatures and save energy. It includes overhead chajjas , pergolas,
verandas and even plants and trees surrounding the building periphery
4. Thermal mass: Is the
capacity of a material to store heat energy. In building terms, it reduces temperature
fluctuations by absorbing heat when the ambient temperature is hotter than the
mass, and then releasing the heat when the ambient temperature falls below the
temperature of the mass. When used effectively, this results in improving
indoor comfort. By using walls of high density material like stone or concrete
blocks the heat gain can be reduced making the temperatures optimum for the
occupants.
5. Ventilation: Ventilation is useful for passive cooling,
where it should be considered along with other design features such like window
size and placement. House having maximum windows in the south
west direction allows good wind flow in Indian context.
