Green roofs keep cities cooler

Cities and other densely populated areas in the country can now be kept cooler and the air over them fresher through the construction of “green roofs.”

Green roofs are thin layers of living vegetation installed on top of conventional flats or sloping roofs.

They are also known as “vegetated roof covers,” “eco-roofs,” or simply “roof garden,” said Alberto Victorino Perez and Conrado Marquez of the Department of Environment and Natural Resources-Ecosystems Research and Development Service (DENR-ERDS) – Region 6 in Iloilo City.

The “green roof” technology is not new to humankind, the researchers said.

“Reminding us of the six-century BC magnificent Hanging Gardens of Babylon of its series of rising 7-meter high terraced garden walls presumably planted to trees, one could just imagine the majestic view it would create if such a structure or structures are built in our modern-day urban environment,” the DENR-ERDS researchers stressed in a joint report titled “Who Needs Green Roofs?”

Perez and Marquez noted that Philippine urban areas, already coping with growth and economic development, are giving way to buildings with metal and concrete rooftops and concrete or asphalt roads and open spaces.

These surfaces catch heat during sunny days. They no longer allow water to infiltrate the ground during rains. Dark rooftops and pavements also absorb and store energy from the sun during the day and release it at night, the researchers said.

The results are increased and extended duration temperatures (known as the “urban heat-island effect),” rainwater runoff, altered micro-climate patterns and loss of greenery.

“While it is somewhat ideal for all these urban areas to be landscaped or totally shaded with canopies of vegetation, preferably trees, green roofs can help provide solutions to these problems,” the DENR-ERDS researchers asserted.

Whole or portion of the roof area, terraces and verandahs can be converted into green roofs and or hanging gardens where one can grow special kinds of plants.