Glass in high-rise buildings making Bangalore hotter

Do not blame the sun alone for rising temperature in the city, as the glass facade that you see on city buildings is also responsible for it.

Unlike concrete walls, which absorb heat, glass facades on buildings reflect heat back into the atmosphere, which results in a rise in temperature in the area around the buildings.

Chandrashekhar Hariharan, CEO, Biodiversity Conservation India Limited, said this phenomenon is called urban heat island effect. He said if Bangalore is home to more buildings with glass facades, the temperature of the city could increase by 2°C to 3°C when compared with outskirts.

Hariharan said the city was already turning into an urban heat island as summers were becoming hotter and winters colder. Glass facades increase the temperature not just outside the building but also inside it, as it traps heat. As a result of this, the temperature of the building rises.

Notwithstanding its side-effects, glass facade is in vogue. Chandra Mohan, a glass facade consultant, said high-rise buildings prefer these because having them expedites construction work, as time required to build concrete walls is eliminated.

Even industry insiders accept that glass facades have major drawbacks. Harmit Singh, managing director, Global Facade Consultants, said glass facades on buildings increase the temperature of the surrounding areas immediately. Further, he said air conditioning load—and with its power usage—increases in the buildings with glass facades. In this backdrop, he said having glass facades was counter-productive.

Krishna Chaitanya, zonal head, Asahi India Limited (a glass manufacturing company), said it was not true that glass causes heat emission in the city. He said even in glass facades, there is a wide range of options to choose from, which can minimise urban heat island effect. He said glasses are classified according to their solar reflective index and the ability to reflect heat; the right choice can minimise reflection of heat. Further, he said the heat-reflection phenomenon can be avoided if glass facades are used on the side of the building that faces north.

Tejas Ranga, business development manager, Asahi India Limited, said it is the cheap glass that causes problem to the environment. He said a variety of glasses are available in the market and people in tropical countries, such as India, should go for darker shades with little reflecting coats, as it decreases heat emission.