White on
For a new take on the green roof movement, the construction industry needs to whiten up, says Andre Cooray
The U.S. Secretary of Energy, Steven Chu, in May this year, recommended that roofs (and roads) worldwide be painted stark white not for aesthetic reasons but to help combat global warming. The theory is that whitewashed cities will reflect the sun’s rays back into space, slowing down the rise in atmospheric temperatures. What’s more, these paler surfaces will consume less energy. This could mean big savings for Americans who spend approximately US$40 billion a year on cooling buildings alone.
Californian researchers at Lawrence Berkeley National Laboratory estimate that if 63 percent of the world’s 100 largest cities paint their roofs white, it would offset 44 billion tons of carbon emissions – the equivalent of taking 600 million cars off the road for 18 years. Chu, a Nobel Prize recipient for physics, sees the whitening of cities taking effect over a 20-year period.
Aside from reducing smog levels (Hong Kong take note), American scientists believe that whitening the planet’s roofs, roads and pavements would slash the global mortality rate, by reducing the number of deaths attributed to heat waves. On average, roofing accounts for one quarter of a city’s surface area and pavement accounts for one third – that’s packing a lot of heat. White roofs can cool buildings down by as much as 100 degrees as they deflect almost 80 percent of energy, as opposed to dark surfaces that can absorb more than the same amount.
The Hilton chain, for one, is looking into going white. In March, the roof of the Anaheim Hilton (in California) was coated with a white paint, filled with tiny hollow glass balls, and layered over a waterproof undercoat made of recycled rubber. This unique paint, created by a former U.S. military scientist, can deflect nearly 85 percent of the heat from the sun’s rays and reduce surface temperatures by as much as 50°C. The director of operations for the hotel, Jerome Annaloro, plans to recommend white roofs for the entire Hilton chain, if utility costs are significantly cut.
“Hong Kong people may not have the awareness yet on white roofs, so they may hesitate about the positive effects,” says Edwin Lau Che-feng, the director of Friends of the Earth (FoE) in Hong Kong. “But white roofs are another practical option for the city to address the urban heat island effect and lower our energy demand on power companies, hence helping to reduce the emissions of greenhouse gases and air pollutants.”
Unless you are Barack and Michelle Obama, live on the Greek islands of Santorini and Mykonos, or are environmentally smart enough to reside in a green residence, you may have to wait some time for your roof to be painted white. In the meantime, Lau says there are lots of ways for Hongkongers to go green at home or in the workplace. Simple solutions range from using energy-saving light bulbs to switching off the standby mode of electrical appliances not in use. But one of the biggest issues in Hong Kong is the excessive use of air conditioning.
“I have experienced some places as cold as 20°C in summer when the outdoor temperature is 33°C,” says Lau. “Using fans to assist air ventilation and reduce the heavy load put on air-conditioning is a good way to save energy.”
According to Lau, government legislation is needed to ensure our buildings achieve a certain standard of energy efficiency. He wants to see pressure placed on developers to build greener buildings, and is lobbying hard for the implementation of mandatory building energy codes – something which will be reviewed by LegCo later this year. Lau also believes that the government should encourage banks to offer subsidised rates for tenants wanting to buy into eco-friendly buildings, as well as provide concessions for developers of green buildings.
“As people are becoming more aware of the environmental problems we face here in Hong Kong and around the world, demand for green buildings will grow in the long run,” says Lau. “And it will be a sustainable business for the property industry: this is the coming world trend. Earning ‘green’ money makes business sense, and simultaneously, saves the earth.”
|
