Buildings with glass facade are becoming increasingly popular across urban India’s skyline. There are positives in having such a design, but the disadvantages in a tropical country such as India far outweigh the benefits
Glass façade buildings have become an indispensable part of urban India’s skyline. In fact, over a period of time these resplendent glass structures have come to represent a city’s economic progress and prosperity. The aura of glass is making an increasing number of clientele to opt for glass-based building architecture, in the process making glass a very important building material in today’s construction scenario. The changing customer preferences have also made the construction sector change its priorities, with the focus shifting from ecological accountability and energy efficiency to looks being accorded more importance and this is where the problem lies.
Modern-day buildings are rapidly turning into energy guzzlers. The reason is the vast amounts of glass that cover the building quickly turning it into a heat trap that take enormous amounts of energy to cool it down as air-conditioning plants work overtime to manage the temperatures at comfortable levels for the occupants. This type of construction activity that keeps the usage of glass as the centre of its design strategy is in vogue nowadays and this is taking a toll on the already scarce energy resources. Our airports in various cities are the best example of this glass-based building approach. Almost all airports sport glass fascia, the result is temperature levels that become twice as much difficult to manage — especially during the summer months. Even though many airports are making commendable efforts to augment the power requirements with solar energy, the extensive use of glass in the airport structure is making the entire exercise a zero sum game.
Traditional buildings that use concrete walls are able to effectively block heat and absorb the same. The same is not possible with glass buildings as they not only increase the heat inside the building but also around it. This is increasingly contributing to the urban heat island effect which in turn causes the city temperatures to be higher by two degree Celsius to three degree Celsius when compared with outskirts. Inspite of these drawbacks, the use of glass is still preferred by builders as it expedites the construction works even though it increases per building energy consumption besides causing a spike in urban temperatures.
The glass façade of a building has its advantages as it gives a sense of open space, and by letting in natural light it reduces the need for artificial light, besides keeping dust and insects out. But there is an ecological cost attached to it. Tropical countries such as India are unsuitable for the use of glass as sunlight is received for 2,688 hours annually as compared to Western countries such as the United Kingdom, which receives 1,480 hours annually. The environmental and weather driven drawbacks have pushed the glass manufacturers to devise several technologies to cut down heat and glare transmission. For instance, a typical version of construction glass being used is double-glazing with air gap in between for insulation. It is used in most high-rise buildings.
Yet another advanced version of the glass, triple glazing, is trying to find a foothold in India as well. But heat transmission through glass is still high compared to other building materials. A study by IIT-Delhi in the national capital city, Jodhpur and Chennai found that energy use typically increases with the increase in glazed area, irrespective of glass type, climate or orientation of the building. For instance, glazing on the northern wall of a building allows the least gain in heat as compared to any other facade orientation. But if the glass wall covers more than 20 per cent of the south-facing facade, the building overheats even in winters.
Glass is not an environment-friendly material as well. It consumes high amount of energy right from its manufacturing to transportation and installation. The embodied energy of glass is between 15.9 and 26.2 megajoules per kg as compared to 1.06 MJ/kg for bricks. The embodied energy of glass increases considerably when used as double or triple glazing or when inert gases like argon replace the air gap to further improve performance. Glass also poses safety concerns, as buildings with glass facades are major fire hazards and hindrance in fire fighting. Glass sheets often do not have fire retardant coatings and shatter once the threshold temperature exceeds.
Given these circumstances the Government must intervene through relevant agencies and regulate the use of glass in upcoming buildings and work toward minimising the ecological footprint of the existing glass buildings.
This will help in checking the obsession with glass. India has a rich architectural heritage that draws from a plethora of cultures that are over hundred of years old. These building practices are suitable for local conditions and must be applied instead of imitating Western building styles and creating glitzy heat traps.
(The writer is an environmental journalist)