HVAC (Heating, Ventilation and Air-Conditioning) and lighting are the most important parts of building design in the present-day energy crisis scenario. The buzzwords in the building industry are eco-friendly, energy efficiency and green concepts.

Lot of research is happening on these principles all over the world. The Central Building Research Institute (CBRI), Roorkee, has been vested with the responsibility of generating, cultivating and promoting building science and technology in the service of the country. CBRI's focus is on green and energy-efficient buildings.

One has to understand that for a comfortable living it is not required to have a so-called modern house with luxuries such as air-conditioning etc. In fact the best design is one which is close to the natural environment with natural air movement and light.

The design of a house/building for clean air movement and natural light is the need and engineers/architects should understand this and provide a comfortable indoor climate. Natural ventilation, mechanical or forced ventilation, mixed-mode ventilation or hybrid ventilation and infiltration are some of the design methods. Natural ventilation is the most effective in increasing occupant satisfaction when it is combined with day lighting as compared to other methods.

Natural ventilation can be achieved by proper building orientation, with windows or trickle vents (a very small opening in a window or other building envelope component to allow small amounts of ventilation when windows, doors, etc, are closed) and by stack effect/ buoyancy (warm air in the building can be allowed to rise and flow out through upper openings, thus forcing cool outside air to be drawn into the building naturally through openings in the lower areas).