As the country faces acute power shortage and the global warming debate hots up, energy conservationists caution against growing number of buildings with glass facades dotting the landscapes of cities as being responsible for energy consumption much in excess that a normal structure would do.
Real estate developers, however refute this as incorrect.
"If you see the structures that have come up recently, they are all mostly made with glass. Right from top to below, you can see huge shinning glass. Though these buildings look very contemporary and stylish, they are the biggest culprit when it comes to energy consumption," says Harsh Narang, director, Modern India Architects.
"Glass building are a very European concept because they don't get much of sunlight. Hence, their main aim is to get maximum sunlight. But, in our country where temperatures at times go as high as 50 degrees Celcius, these glasses take in more of sunlight. Hence, the offices use more air-conditioners directly resulting in higher consumption of electricity and also in the form of carbon-dioxide emission and also CFCs that air-conditioners generate causing damage to the ozone layer," he adds.
According to a study conducted by Chartered Institution of Building Services Engineers, London, a complete glass building consumes four times more electricity than a normal building.
"The logic being that since the glass is transparent, higher amount of infra red radiation comes in. They are short wave radiation when they enter, but the moment it enters the room it becomes long-range radiation. Hence, a higher capacity air-conditioner is required to keep the indoors cool. India is a tropical climate and these glass building are just not suitable," says Meenakshi Dhote, assistant professor, Department of Environment Planning, School of Planning and Architecture, Delhi.
But real estate developers refute all such charges. "Such arguments are totally baseless. If the glass is provided with 'U' factor, then it can stop a major portion of radiation from coming in. Moreover, there are also various kinds of glasses that can be used, like double glass which are also very helpful," says K K Bhatacharya, executive director, DLF, a major real estate developer using glass as a key component in their constructions.
"The glass saves lot of energy too because the offices would be less dependent on lighting and hence saves on electricity. If the architecture is done in such a way that not much of sunlight falls on these glasses during the peak time, it can also cut down on the radiation effect. Moreover, ACs are used only for few months," he adds.
According to sources in The Energy Research Institute, which has done extensive study on glass buildings and energy consumption, the proper or optimal use of glass can cut down on energy demands by at least 10 to 15 per cent of a normal building.
"Glass allows in direct radiation and direct radiation is 80 per cent of the total heat generated. Hence, the usage of AC increases meaning more power is used leading to more shortage," says a senior official, TERI.
"Glass structures are just not viable in a tropical country like India," he adds.
Other architects point out that since the focus is now on large glass buildings, there is very little chance of designing a glass building facing no direct sunlight.
The government has also understood the role played by such glass structures in guzzling higher energy and also contribution to global warming. According to the recent Energy Conservation Building Code, future projects can have not more than 40 per cent of gross wall area as glass, the official says.
Other countries are also taking initiative in this regard.
Even the main issue for discussion at G8 Summit held recently in Berlin was global warming.
The Chinese state council has recently ruled that air conditioning must be 26 C max in China's public buildings, a move to cut down on power consumption.
Experts point that the main reason why developers still use glass for many of their projects is because of the cost as well as time factor.
"There is no doubt that glass structures take less time to construct unlike a normal structure," says Bhatacharya.
"Though, these glass structures come up very quickly and is also cost effective, other than looking good, such buildings are a major cause for higher consumption of electricity. With cities facing electricity shortage and rising temperatures, such structures add to the woes of everyone," says Narang.
