No evidence to suggest buildings with glass facades utilise more energy: Puri

The government Thursday said there is no evidence to show that buildings with glass facades utilise extra energy.

Housing and Urban Affairs Minister Hardeep Singh Puri told the Lok Sabha that in fact, a glass building when properly designed can have benefits.

To a question on whether energy conservationists are cautioning against growing number of buildings with glass facades, which add to global warming, Puri said no such reference has been received by the government.

"Glass clearly has an aesthetic value but there is no evidence to suggest that the use of glass facade in buildings per se results in extra consumption of energy," he said during the Question Hour.

He also urged the members to let him know if there is any study done in India or outside which demonstrates that the use of glass facade is actually contributing to global warming.

"Our effort all along has been to construct buildings which are environmentally sustainable and friendly. If there is any evidence which comes that glass facade has the opposite effect, we would certainly look at that evidence," Puri said, adding that he had lived for five happy years in an entirely glass building, the Trump Tower, on Second Avenue on 46, New York.

The minister also noted that he was not aware of anyone having brought to attention the need to move in a direction which seeks to curb the use of glass.

Puri said the Bureau of Indian Standards (BIS) has issued a Code of Practice for use of glass in buildings in 2019 covering aspects such as general methodology for selection, energy and light, fire and loading and safety related to human impact.

The National Building Code 2016 has provisions for use of glass based on their thermal properties to optimise solar load while also taking care of the safety concern in buildings.

Citing a study by IIT-Delhi in July 2011, the minister said though glass facade leads to higher energy consumption in buildings, the actual quantum of consumption depends on various factors such as building type, glazing type, glazing orientation and climate type.

The study was titled 'suitable glazing selection for glass curtain walls in tropical climates of India'.

"A reference has been made to a Study by IIT Delhi which says that it consumes four times more energy. I have personally read that study... there is no such conclusion in that study," he said.

"... glass buildings facing south use more energy, those facing north use less energy and those which are facing east or west use equal amount of energy. If you use glass in terms of double glazing and insert certain gas into them, like Argon or Crypton, the evidence is that the building consumes less energy," Puri noted.

The minister also said that 12 states have adopted the Energy Conservation Building Code (ECBC).

ECBC 2017 prescribes minimum energy performance standards for building envelopes, including glass facades for parameters like energy and heat transmission, solar heat gain and visible light transmission.

The minister said ECBC compliance has been recommended for commercial buildings.