Lahore could soon be listed among the cities that have opted to expand their green cover, albeit vertically. The Lahore Development Authority (LDA), Cantonment Board, Defence Housing Authority (DHA) and the Metropolitan Corporation Lahore (MCL) have recently shared their presentations on rooftop gardens.

The LDA has already started issuing notices to high-rise buildings to convert their concrete roofs into gardens and building bylaws are being amended to make rooftop gardens mandatory.

It may be mentioned here that the Lahore High Court (LHC) recently constituted a committee to find solutions for air pollution and smog in the provincial metropolis. Abdul Razzaq Chauhan, the key person in the committee, who is also the chief engineer at TEPA, tells TNS that rooftop gardens not only have an aesthetic appeal but they also contribute to lowering the temperature in the surrounding area.

“Green roofs have other uses too,” he says. “For instance, you can grow fresh vegetables.”

Shakeel Ahmed, a modern-day farmer, seconds Chauhan: “Rooftop farming will require very little watering. Also, using some new-age techniques these farms can be utilised to produce a harvest that could feed the local population.”

He also speaks of green roofs as becoming an increasingly popular trend across the world.

The idea is to counter the effects of climate change. As Chauhan puts it, “Green roofs help to reduce energy use by bringing down the demand for air-conditioners. Besides, they check air pollution and ozone levels. Several cities have already made laws on this [rooftop gardens].”

Rooftop gardens and vegetation help reduce dust in the air, which is one of the main contributors of smog. Besides, they provide great insulation by retaining heat in winters and keeping the temperatures on the cooler side in summers.

Quoting a study, he says that in 2010 Copenhagen made rooftop gardens mandatory for all new commercial buildings with a roof slope of less than 30 degrees. In 2016, the city of Córdoba in Argentina issued a bylaw that mandated all buildings with rooftops of more than 1,300 square feet to be turned into green roofs. The same year, San Francisco decreed that 15 to 30 percent of roof space on new buildings should incorporate solar panels or green roofs, or both. More recently, the New York City Council passed a law to reduce greenhouse gases; it includes a requirement for green roofs or solar panels, or a combination of both, on newly constructed buildings. Washington DC’s storm water regulations and Philadelphia’s tax credit, too, encourage green roofs.

Green roofs also find favour with the environmentalists. They say that rooftop gardens and vegetation help reduce dust in the air, which is one of the main contributors to smog. Besides, they provide great insulation by retaining heat in winters and keeping the temperatures on the cooler side in summers.

The insulation thus provided also applies to noise pollution as a combination of soil and plants helps absorb, reflect and deflect the sound waves.

Chauhan reveals that it took several meetings with urban planners on introducing the concept of rooftop gardens in the city, before the modalities were worked out. “In the first phase, plantation shall be made mandatory on roofs and balconies of tall buildings. To ensure implementation, the building bylaws shall be amended,” he says.

Talking about the logistics and technical requirements for rooftop plantation, he says that the strength of a building structure must be considered before initiating any work of the sort: “The weight of a lavish garden can be too much for a weak roof to bear.

“Secondly, a waterproofing system must be installed on top of the buildings with a complete drainage system. Roof protection mats and rainfall management systems should also be installed.”

Going green is an expensive proposition. It can increase the overall cost of a commercial building. But, considering its long-term benefits, it’s an idea worth buying.

The writer is a city reporter at The News, Lahore