Glass enveloped buildings are quite in vogue in our country. Glass, which is actually meant to be used as a green-house material, allows the sun’s infrared rays to enter the room and heat the air inside. This is great if you live in a cold climate, but for most parts of India where the temperature is mainly warm or hot, it is not such a ‘cool’ idea.
Have you ever felt the sudden rise in temperature when you enter a non air-conditioned glass building? Floor-to-ceiling glass buildings are an extremely wrong concept for India, unless you’d prefer getting naturally tanned and baked, or want to spend huge amounts of electricity on air conditioning.
Natural Light vs. Air Conditioning
Glass buildings are appreciated for letting natural light in during the day. Avoiding artificial lighting helps save energy, but in hot climates, the increased use of air conditioning can consume five to ten times more energy. Lighting consumes very less power compared to air conditioning. For instance, a 200 square feet room will require about 50-100 watts of light and an air conditioner of 1500 watts. If you have floor-to-ceiling glass windows in the sunny side, it would require a bigger air conditioner (say about 500 watts more) or the same air conditioner will have to work longer. Using 50 watts of light is definitely better than using 500 watts of air conditioning.
Comparing insulation properties (R values – denote the thermal resistivity of a material, higher the better for insulation), the best expensive multi-pane vacuum insulated glass would be R12 at max. Solid walls are R20 or more. Normal glass is around R4. IIT Delhi did a study  in Jodhpur, Delhi and Chennai and it was found that the use of energy increased with the increase in glazed area, irrespective of the glass type used.
The Best Way To Use Glass For Your Home Structure
Windows are great for ventilation and it is healthy to have rooms with natural daylight. Place glass on the north and eastern sides (low direct sun heat) of the house as it can be a good solution for warm Indian climates. The glass should preferably have the option of opening and closing and should be covered with thick curtain or blinds while there is direct sunlight through the day, especially if the air conditioner is being used. Choose the glass with highest reflective and insulative properties. You can use window films or tints on your existing glass to reduce the heat and enjoy the view at night without harming the environment.
Image Source: Wikipedia Commons
 – Down To Earth ‘Reflections On Glass’ 15 December 2012