Periscope
Doubts over new green panels on building walls
by Toni Ip
Urban planner and environmental experts are doubtful about
the effectiveness of the government's plan to fix vertical green
panels on the building walls of a public housing estate in
construction to help reduce the heat and save energy
consumption.
The results of the new system in easing urban heat island effect would be limited by merely installing the greenery panels in just a few buildings, said Edward Ng Yan-yung, a professor of architecture.
"Only if the (vertical green) panels are installed to every building in a large area then it is able to really reduce the heat island effect," the scholar of the Chinese University of Hong Kong said.
The Housing Department announced in February that the vertical green panel system would be carried out in the housing estate of Eastern Harbour Crossing (EHC) Phase Four in Yau Tong. Construction of the three blocks of public housing is scheduled to be completed in 2009.
Three trial vertical green panels have been erected for design reference in the construction site. Both the greenery and the vertical surface to be used in the buildings will be tried out.
A spokeswoman for the Housing Department, May Tham
Ley-bay, said aluminium trays holding plant species with a thin
layer of soil would be installed initially at rooftop of the
construction site office to monitor the growth of the plants. The trays will then be fixed on the external walls of the buildings
when the construction is completed, and after the kinds of
plant species suitable for growth on the panels and for greening
effect have been found out during the trial.
However, Ms Tham did not give any example of plant species to be used in the trial.
She said greenery could reduce heat island effect, contributing to building insulation and energy efficiency.
Overseas studies showed that greenery planted on rooftops could lower room temperature of the top storeys by one to two degrees Celsius and in turn reduce usage of air-conditioning, she cited.
Andrea Ng Wai-yee, chairman of local green group Earthcare, doubts the possible reduction of energy and air-conditioning usage in reality, as people's perception is not changed.
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