LCQ 13: Government actively promotes urban greenery
Wednesday, June 15, 2005
Government Press Release

Following is a question by the Hon Choy So-yuk and a written reply by the Secretary for the Environment, Transport and Works, Dr Sarah Liao, at the Legislative Council meeting today (June 15):

Question:

A study on urban heat island effect is reported to have revealed that a 1 degree Celsius rise in local temperature will result in an increase of around 1.7 billion dollars in expenditure on electricity. The incidence rates of some infectious diseases will also rise. Measures encouraging the construction of more green roofs on buildings have been adopted in many countries in order to mitigate urban heat island effect. In this connection, will the Government inform this Council whether:

(a) building managers of government offices buildings, subvented schools, public hospitals and other government buildings will be required to implement green roof projects on their buildings; if so, of the details of the requirements; if not, the reasons for that; and

(b) measures will be formulated to encourage building managers of private buildings to implement green roof projects on their buildings; if so, of the details of the measures; if not, the reasons for that?

Reply:

Madam President,

The heat island effect is a terminology commonly used to describe the cumulative impact arising from urbanisation with tall buildings and concrete structures, large fleet of vehicles, extensive use of air conditioning and insufficient natural ventilation caused by congested cityscape. The reduction of its effect often requires a hybrid of measures such as provision of urban breezeway; stepping building heights; better planning of the orientation and disposition of building blocks to enhance air flow; improving insulation of buildings and incorporating other design features that reduce heat load, as well as provision of more urban greenery to provide shading and cooling for pedestrians.

Despite a lack of conclusive evidence to demonstrate that roof-top planting could indeed help attenuate the heat island effect, the Government is actively promoting urban greenery as a positive means to enhance our living environment in Hong Kong. To this end, the Architectural Services Department has incorporated since 2001 the design of landscaped roof/terrace in new government building projects where practicable. As a further step, we are currently examining through the Steering Committee on Greening the feasibility of additional measures to encourage roof-top planting in private developments.

probably, lesser glassy buildings will help ;)

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Breeze block blamed for urban heat
Hong Kong Standard
Thursday, May 22, 2008

Mong Kok and Causeway Bay are sweltering with the hottest temperatures in the city because of the urban heat island effect.
Professor Tim Oke of the University of British Columbia, who pioneered the theory, said the effect is due to the density and height of the buildings that block the sea breeze.

"It's because of the way Hong Kong is built that has caused an excess of temperature and there's no sign of this slowing down," Oke explained.

Experts said continued reclamation on the harborfront has worsened the effect over the years particularly in reclaimed areas, such as Olympic station.

According to a Polytechnic University study, temperatures in the territory's rural and urban areas may vary by as much as 12 degrees Celsius.

Hong Kong is one of six cities, including Atlanta and Vancouver, which experience maximum temperature differences.

"Twelve degrees is the maximum difference so Hong Kong is at the top of the scale," Oke said.

"If Kowloon is made bigger through reclamation the intensity of the UHI effect will increase. The cleaner air from the harbor is being intercepted by the walls of buildings."

Planners, Oke said, should build at a lower density to allow ventilation.

The PolyU research found the average temperature difference between rural and urban areas between 7 and 8 degrees on a winter night and between 5 and 6 degrees during summer.

PolyU reviewed satellite images and collected ground data through 20 trips on special mobile vehicles with temperature sensors.

Mapping team acts to turn down the city heat
6 October 2009
SCMP

Developers are being urged to undo the damage they have done to residents' quality of life by acting to curb the "heat island" effect that has made parts of Hong Kong up to five degrees hotter than people can comfortably tolerate.

A government team has drawn up the city's first climatic map - derived from a four-year study commissioned by the Planning Department in 2006 - that highlights a dozen densely populated urban areas as hot spots.

They are Sheung Wan, Central, Causeway Bay, Wan Chai, North Point, Tsim Sha Tsui, Tsuen Wan, Kwun Tong, Sham Shui Po, Mong Kok, Lai Chi Kok and Tseung Kwan O.

"These areas are five degrees Celsius higher compared with an environment offering people thermal comfort," Professor Edward Ng Yan-yung from Chinese University, who led the study team, said.

As well as looking at the air temperature of each district, the map takes into account the development density, topography, wind velocity, humidity, radiation and human activities of each area to calculate the "physiological equivalent temperatures", which measure thermal comfort - conditions in which humans neither feel too hot nor too cold.

While environmentalists have warned for years about the heat effects of high, wall-like buildings and destruction of urban greenery, Ng points to two new developments that are likely to make Tsim Sha Tsui even hotter.

"The building of The Masterpiece [a residential high-rise] alone will add one to two degrees Celsius to the district," Ng said. "It's not about its height but its large podium blocking the airflow."

He said the removal of a grassy, tree-shaded hill inside the former marine police headquarters - a once-green oasis at the tip of Tsim Sha Tsui now redeveloped as Heritage 1881 - was also expected to raise the temperature in the district.

He urged the government to protect other sites along the city's breezeways - open areas that channel wind flow - from massive developments on new rail lines that threaten to turn them into hot spots, too. They include Kowloon City, Ma Tau Kok, West Kowloon, Shek Kip Mei, Kwun Tong industrial centre, Kennedy Town, Wong Chuk Hang and waterfront areas of Tseung Kwan O.

Apart from protecting the breezeways, developers should also reduce their projects' impact on the wind flow, the study team that produced the draft map said.

The team said this could be done by including a minimum of 30 per cent green areas in new developments, using building materials that absorb less heat and are therefore cooler, and requiring shaded areas and building-free zones in hot spots.

"What happened to Tsuen Wan and Nam Cheong are mistakes," Ng said, referring to wall-like buildings proposed above Tsuen Wan and Nam Cheong stations. "The proposed developments there are unsustainable in the long run and building air-conditioned malls is not a solution to the heat island effect," he said.

A Planning Department spokeswoman said the map drawn up by the consultants would be refined with more experts' views and the department would consult the public when the study's recommendations were released next year.

New building and planning rules to restrict development designs have been proposed by the Council for Sustainable Development, which is holding a public consultation due to end this month.

Under the proposal, developers could be asked to leave wider pedestrian streets and be banned from building podium structures. But whether to implement it by law or with incentives is still subject to heated debate among interested parties, and no timetable has been set.

In Germany, federal building law states that developments must not worsen the environment. The country drew up a climatic map in the 1980s and a team of experts was hired to advise planners on development scales and designs.

Tokyo started a similar initiative in 2002. The government is planning to demolish overpacked building blocks along Kanni Road to bring sea breezes back to the city centre.

The chairman of the Professional Green Building Council, Wong Kam-sing, said the study offered useful data for refining the city's planning rules. He said the labelling scheme for green buildings would be revamped in November.

The government and developers wanting to certify their developments as environmentally-friendly will have to conduct air ventilation studies to demonstrate they have no or little impact on wind environment.

"The result of the air ventilation study will become an influential factor in the new scheme of assessment," he said. Developments' impact on wind environment only accounts for two of 110 points under the current scheme.

The administration pledged in May that all newly built government buildings with a floor area of more than 10,000 square metres would be certified.

Wong said it was not necessarily costly to design a cool environment. "You can just do it simply by using light-coloured paint and tiles," he said, adding that the city showed its insensitivity by constructing buildings in dark colours and using asphalt to pave roads.

"You can see the wit of Greece, where many houses are built in white," he said.

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Source: http://www.flickr.com/photos/hkgreensense/4901442041/sizes/z/in/photostream/