LCQ 10: Rooftop greening projects for buildings

Following is a question by the Hon James To and a written reply by the Secretary for the Environment, Transport and Works, Dr Sarah Liao, in the Legislative Council meeting today (November 15):


It has been reported that a recent research conducted by the University of Hong Kong has revealed that the greenery planted on rooftops of buildings can lower the room temperature in the top storey of such buildings by 6 degrees Celsius, indicating that green roofs can help reduce energy consumption.  Moreover, the Government indicated in February this year that green projects had been incorporated into nearly 40 Government building projects under planning or construction by the Architectural Services Department ("ASD").  Furthermore, green roofs will be tried out by the Housing Department ("HD") in a newly established public housing estate and two shopping arcades.  In this connection, will the Government inform this Council:

(a)  among such green projects of ASD, of the number of completed ones, together with a breakdown by the types of buildings; if none has been completed, the reasons for that;

(b)  among the completed green projects of ASD, of the number of those involving the planting of greenery on rooftops, with a breakdown by whether direct soil planting on rooftop surface or container gardening is used;

(c)  of the specific measures to encourage owners of private buildings and subvented organizations to implement roof greening projects for their buildings, in order to beautify the city and reduce heat island effect; and

(d)  whether HD plans to extend rooftop greening projects to all the existing public housing estates in the territory?


Madam President,

(a)  Since green roofs can help improve townscape, attenuate urban heat island effect, enhance the effectiveness of heat insulation facilities and save energy, the Architectural Services Department (ArchSD) aims to implement green roof projects for new government buildings as far as practicable.  Starting from 2001, the ArchSD has incorporated rooftop or podium landscape designs in new government building projects wherever practicable.  About 50 projects with such green features have been completed.  These include schools, office buildings, hospitals, community facilities and government quarters.  Please refer to Annex I for breakdown by building types.

(b)  For those completed rooftop/podium green projects, the scope of greening works aims to dovetail the use and design of the respective rooftops/podiums.  In most cases, soil layer is placed on the rooftop surface for growing different kinds of plants.  Generally speaking, this planting method is more cost effective.  Flower pots are used when there are space or other kind of constraints, for example, building services installations.  Please see Annex II for relevant breakdown.

(c)  Apart from actively implementing rooftop green projects for new government buildings, the Administration is also studying the feasibility of promoting greening projects in private developments.  The Buildings Department has commissioned a consultancy study on sustainable building designs which aims at developing guidelines on sustainable building designs, and the provision of more green features is one of the issues under such study.  The Administration will carefully study the outcome of the report before deciding the way forward.

(d)  The Housing Department (HD) has always attached importance to environmental protection and has planted greenery on rooftops of shopping arcades and car parks in some estates.  To further promote greening in housing estates, plans are in hand to adopt green landscape designs on the rooftops of certain new projects.  In doing so, indigenous herbaceous plants that can grow more easily will be planted with a view to increasing the ecological value of the landscaped area.  The residential buildings at the Eastern Harbour Crossing Site Phases 3 and 4, expected to be completed in 2008 and 2009 respectively, will be the first batch of buildings to try out the design.  Upon their completion, the HD will evaluate the outcome to consider whether and how roof greening should be extended to other public housing estates with regard to its management, conservation and mosquito elimination.

Annex PDF Version

End/Wednesday, November 15, 2006