Coastal projects may heat up HK, green group says
Coastal reclamation could worsen the heat-island effect and make city centres further inland too hot, leading to higher energy consumption, an environmental group warned in a recent study.
Green Power's research, released yesterday, found that when high buildings on the coast block ventilation and add to heat sources, temperatures get progressively warmer by around 3 degrees Celsius as one travels from outer areas into the city centre.
This could trigger higher energy consumption inland for air conditioning, said Dr Man Chi-sum, chief executive of Green Power.
The study was made public just a day after the government identified 25 potential reclamation sites - mostly in coastal areas in Tuen Mun, Tolo Harbour and Tseung Kwan O - tipped to increase land supply for housing projects.
The heat-island effect is widely blamed for the fact that Hong Kong's annual mean temperature is generally higher than comparable cities worldwide.
Green Power's estimates were based on a number of temperature measurements taken since 2001 along selected routes in different parts of the city.
One route crosses the Kowloon peninsula from the west end of Jordan Road to Hung Hom pier. It cuts across busy corridors and dense areas, including Nathan Road. A temperature difference of 5.5 degrees was measured between the centre and ends of the 3.1-kilometre route.
Man, the CEO, said past reclamations had failed to take into account such thermal impacts, and he called for better assessments and allowing more space for green areas.
Based on its findings, Green Power projected what it called a gradient of maximum temperature increase - between 2.2 and 3.7 degrees per kilometre - from the edge to the centre.
Dr Cheng Luk-ki, who was in charge of the study, said the findings showed the temperature implications of urban expansion. 'As the city grows outwards, the temperature at the centre will generally increase, too,' he said.
Cheng said if temperatures rose by 3 degrees for every kilometre, then the 600-metre wide Central reclamation could potentially cause a 1.8degree rise in the heart of the city.
He said vegetation cover could lower temperatures by 0.8 degrees in urban areas, according to overseas studies.
'Our next administration should tackle this issue seriously by looking into whether urban redevelopment must be for housing construction only, or they could be turned into green areas,' Cheng said.
Overseas studies had linked the heat-island effect to a 3 to 8 per cent rise in electricity use, the group said.
The year when Hong Kong had the warmest temperature on record, 24 degrees Celsius on average, since 1884