Glass is the most fascinating building material invented by the mankind and is loved and preferred by the architects, engineers and the entire building community. One need not go too far to find out reason for this special love for the material. Glass has the ability to covert even the ugliest building into a beautiful eye arresting structure. No other material can replicate the aesthetic quality of a glass. It’s becoming increasingly common to see large glass envelopes on buildings today.
But times are changing so is the climate! With the climate crisis brewing with some countries have already gone into climate emergency mode, people’s perception about this building material too is changing. Recent heat waves in Britain and Paris have only exacerbated the case of glass which once was considered ‘wonder material’.
Further, manufacturing process of glass itself involves lot of energy consumption. The embodied energy of glass is estimated between 15.9 and 26.2 megajoules per kg vis-a-vis 1.06 MJ/kg for bricks. The embodied energy of glass increases considerably when used as double or triple glazing.
Benefits of glass
No doubt one cannot overlook the benefits of glass in building construction. It is one of the versatile and oldest materials in the building industry. Glass-fronted structures have become popular because they altogether change the exterior aesthetics of the building and give an extra edge to the building vis-à-vis other buildings. Further, it gives a great view from inside the building as well. It also lets plenty of natural light inside the building. It has also architectural applications in doors, windows, partition, etc.
Disadvantages of glass
But the sunlight also brings in lot of heat. As there is no place for it to naturally escape, whole of the building tends to get heated up. One of the normal ways to get relieved of this extra heat is through the usage of air-conditioning. But here solution is not a solution in its real sense as it only aggravates the problem. Worldwide built environment is responsible for around 35-40% carbon emissions and major portion of them is accounted for by glass structures and air-conditioning. Reducing unnecessary energy consumption in buildings—and the carbon dioxide emissions that accompany it—ranks near the top of the list of newfound policy goals.
Shortcomings of the glass buildings were debated and criticized in the past too but such debates had rarely reached present magnitude and intensity. Perhaps the most outspoken about the glass buildings was Swiss architect Le Corbusier, who in the late 1940s launched an attack on the design of the UN Secretariat, arguing that its large and unprotected glass surfaces were unsuitable for the climate of New York. Despite the criticism by the legend, use of glass in buildings has become rampant over the years.
Usage of glass in USA
However, future doesn’t seem to be as smooth as it was for glass as a building material. For example, the New York programme, popularly known as OneNYC 2050, has set out to achieve carbon neutrality and 100% clean energy by 2050 by modernising the city’s buildings, transport, and boosting clean energy. The New York City will be ordering all existing buildings of 25,000 square feet or more, of which there are 50,000 across the city, to carry out energy upgrades in a bid to slash their emissions. According to estimates, buildings account for 70% of the city’s carbon pollution. The plan bans inefficient all-glass constructions, many of which have defined the city’s iconic skyline. Such buildings will have to meet strict conditions to be built in future. So, it will be tough time for glass as a building material in USA.
Usage of glass in Europe
In Europe too awareness about ill effects of excessive use of glass in buildings is increasing. Though the Mayor of London has ruled out any New York style plans but prominent citizens are supporting such plans for the city. It may be recalled here that UK has recently declared climate emergency and some people believe that such emergency would have no meaning unless a connection is established between the emergency and all-glass buildings. However, new London Plan which will become effective next spring will require construction firms to make an assessment of a building’s energy use across its whole life-cycle.
Usage of glass in India
In India, however, glass is being increasingly used in the buildings and most of the times users don’t know the repercussions of increased use of glass in the buildings in a tropical country like India. Even Building Code is lenient on the usage of glass in the structures. Bureau of Energy Efficiency’s (BEE) energy conservation building code allows a maximum WWR of 60 per cent which is very high for a tropical country like India. Therefore, BEE needs to be more pragmatic while deciding on the WWR.
There is no doubt that the threat climate change poses is existential and the way we build and maintain them are one of the main culprits contributing to this factor. We are left with only two options, either to change the way we make our built environment so that it produces no CO2, or to carry on, business as usual, and live with the consequences. Choice is entirely ours.