From news.gov.hk:
'Green roofs' set for new housing estates (http://news.gov.hk/en/category/environment/061115/html/061115en04004.htm)

Great news.

Is there any green roof in HK now?

Great news.

Is there any green roof in HK now?

I know some schools has installed the green roof on their roof and some private resident houses have that also. But I have heard if you don't treat the roof well, it will cause many bugs problem there.

This type of roof helps conserve energy by insulating the building. There is a lot of open space at the top of residential buildings to have a green oasis that is easy to add and cheap to maintain. However, with some residential skyscrapers reaching 50 stories these days, a potted plant at the roof might get blown off by a strong gust of wind during typhoon season.

November 15, 2006
Greening


'Green roofs' set for new housing estates



The Housing Department will cover the rooftops of newly-built public housing estates with indigenous herbaceous plants for a greener environment.



Secretary for the Environment, Transport & Works Dr Sarah Liao told legislators today that the first batch of buildings to try the design will be residential blocks on Eastern Harbour Crossing Site Phases 3 and 4, which will be completed in 2008 and 2009.




The department will evaluate their success and consider how rooftop greening can be extended to other estates. Dr Liao said green roofs save energy by creating a cooler environment.



The Architectural Services Department has worked on the initiative since 2001, and finished about 50 projects on new Government buildings, including schools, offices, hospitals, community facilities and quarters.



The Buildings Department is studying the feasibility of promoting greening projects in private developments to develop a building design guideline. The outcome of the study will help the Government determine the way forward.

Same thread here (http://skyscrapercity.com/showthread.php?t=410629).

HD to test out more green initiatives
Tuesday, February 20, 2007
Government Press Release

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The Housing Department is testing a series of greening initiatives at its construction projects to further enhance the provision of greenery to congested urban sites.

The Deputy Director of Housing (Development and Construction), Ms Ada Fung, said the department had always attached importance to environmental protection and greenery had been planted on rooftops of some of its shopping arcades, carparks and related small structures.

To further explore greening in housing estates, Eastern Harbour Crossing (EHC) Phase 4 in Yau Tong is testing a vertical green panel system in form of modular prefabricated external cladding.

“The panels can be cladded on vertical surfaces as well as installed at roof areas. The modulated prefabricated panels enable easy on-site installation and future maintenance works.”

“To test the most optimal soil mix and plant species mixes for the panels, trial panels will be installed on site during construction stage and relocated to their permanent location upon completion of the project,” Ms Fung said.

EHC Phase 4, scheduled to be completed in mid-2009, consists of three 41-storey domestic blocks with 2,369 flats. A total of 2,650 square metres greening space will be provided.

Green roof is also proposed at EHC Phase 4 at all roof areas with minimum four hours direct sunlight per day including roofs of lift towers and ground floor canopy. Horizontal trellises are provided at both sides of the roof top of the footbridge and double deck walkway to allow growing of climbing species to enhance visual and thermal comfort.

“Greenery at roof offers wide range of benefits such as helping to reduce the heat island effect, contributing to building insulation and energy efficiency, and enhance visual comfort,” Ms Fung said.

To explore the feasibility of large reusable panels at hoarding, the construction site of EHC Phase 4 has adopted the pilot concept of green hoarding.

“The large reusable panels, which will serve as dust and noise screening devices, are demountable and can be moved to other construction sites.”

"To improve the visual effects of man-made slopes and high retaining walls, all phases of EHC will carry out greening works to slopes and wall surfaces as far as possible to improve the overall environmental quality of the ‘hard’ surface to increase green coverage and reduce heat island effect of the domestic blocks," Ms Fung said.

“Different design measures will be adopted to cope with specific site condition and constraints,” she said.

天台空中樹林大樓降溫7度
28/07/2008

http://the-sun.on.cc/channels/news/20080728/img/sn08072804_big.jpg

【本報訊】烈日當空，天台頂層吸熱猶如「火爐」，中華電力於荔枝角深旺道變電站旁設備大樓天台設立全港首個空中樹林，測試樹木對減低室溫、空氣污染物及二氧化碳量的效能。中電指出，空中樹林最高可為建築物降溫攝氏五至七度，一年可為建築物節省空調耗電量約三成；但由於負重問題，現有建築物不能貿然設立空中樹林，建造商一般要增加兩至三成成本裝上防水及樹根障壁等設備。

中電輸電及供電業務部總監潘偉賢表示，剛於五月落成的空中樹林面積一千平方呎，工程須在天台地面鋪上九層，包括混凝土板、樹根障壁、排水及過濾層及泥土表層等，每平方米承托力可達二千五百公斤，較一般樓宇的三百公斤高。樹林內栽種十八棵大中型樹木及地面草皮，主要為包括土沉香及麥門冬等本地樹種及樹根較短的品種；周邊則安裝了三組溫度、空氣懸浮粒子、太陽輻射及泥土濕度等測試儀器。

研究可否推廣
他指現時不少樓宇有設置天台花園，但主要為零散分布的草本植物、灌木及盆栽，降溫僅攝氏一至兩度；但空中樹林則以緊密方式植樹苗，三至四年後便可造成樹冠交錯的屏風效果，阻隔熱力傳送，降溫最高達攝氏五至七度。

與中電合作進行科研的香港大學地理學講座臈授詹志勇稱，稍後會收集數據研究及驗證空中樹林應用於香港的可行性，他建議政府可透過津貼、技術指引及比賽等，鼓勵多建空中樹林。 http://the-sun.on.cc/channels/img/endmarker.gif

LCQ18: Rooftop greening
Wednesday, October 29, 2008
Government Press Release

Following is a question by the Hon Joseph Lee Kok-long and a written reply by the Secretary for Development, Mrs Carrie Lam, in the Legislative Council today (October 29):

Question:

It has been reported that some contractors have recently introduced a new rooftop greening technology from Japan which uses lightweight materials underneath the growing medium in place of conventional soil. As a result, the total weight of the greening project is only one-eighth of that for common rooftop greening projects, and roofs with smaller loading capacities can also carry out greening works. However, the cost of such technology is relatively high. In this connection, will the Government inform this Council:

(a) whether it has adopted the above new technology in carrying out rooftop greening works for government buildings; if it has, of the expenditure involved for such works; if not, the reasons for that;

(b) of the latest rooftop greening technologies adopted by the Government at present and its effectiveness;

(c) whether it has provided the relevant technical and funding support to the private sector to promote rooftop greening; if it has, of the details; and

(d) whether it will formulate a comprehensive long-term strategy to actively promote rooftop greening so as to alleviate the continual rise in Hong Kong's temperature?

Reply:

President,

(a) & (b) The Government has been promoting greening to improve our living environment. This includes actively implementing rooftop greening where practicable to enhance the cityscape and mitigate the heat island effect in urban areas.

We are also continuously reviewing and have introduced new technology where necessary to achieve better results in rooftop greening. The lightweight planting soil mentioned in the question is one of the types of technology adopted. We have used this in individual projects on a trial basis and achieved satisfactory result. Details are as follows.

Lightweight planting soil is usually produced from pumice, light expanded clay aggregate and other synthetic materials. This type of new technology has become more widely adopted in green roof projects since 2007. In that year, we began to introduce this type of technology in roof renovation and alteration projects in Government buildings. As the weight of lightweight planting soil is only one quarter of that of normal planting soil of the same volume, it helps to cope with the loading constraints of existing buildings. We have also introduced lightweight plastic drainage modules to replace traditional granular drainage layer to further reduce the loading imposed by green roofs on buildings. Since 2007, we have adopted these types of technology in 21 projects at a total additional expenditure of around $4.4 million.

However, the cost of using lightweight planting soil and lightweight plastic drainage modules is higher and is about three to four times of the cost of using traditional materials (assessed on the basis of unit planting area).

(c) The Architectural Services Department (ArchSD) completed the Study on Green Roof Application in Hong Kong in 2007 which reviewed the latest concepts and design technology of green roof and recommended technical guidelines suitable for application in Hong Kong, covering various aspects including choice of plants, waterproofing layer, thermal insulating layer, drainage layer, planting soil, irrigation as well as maintenance and repair. The report has been uploaded onto ArchSD's website for public access so as to promote awareness and understanding of rooftop greening.

Non-profit organisations (such as schools and social service organisations) may apply for funding under the Environment and Conservation Fund (ECF) administered by the Environment Bureau (ENB) to subsidise greening works, including green roof projects. ENB has organised briefings for eligible organisations to explain the application procedures and has invited professionals with relevant experience to share their insight on early project planning and preparatory work as well as matters required attention. The ECF has already subsidised 47 non-profit organisations to undertake greening projects. The Government hopes to continue to promote rooftop greening in private buildings through the ECF.

(d) We strive to include rooftop greening in so far as possible in the design of public housing estates, new Government buildings and renovation of existing Government buildings. Moreover, the Government is studying the feasibility of promoting green features in private development projects. The Buildings Department has commissioned a consultancy study on sustainable building designs to explore the feasibility of providing more green features in private development projects so as to improve the urban living environment. The Government will consult the public and consider their views before deciding on the way forward.

LCQ14: Implementation of green roof projects for government buildings
Wednesday, November 10, 2010
Government Press Release

Following is a question by the Hon Lau Kong-wah and a written reply by the Secretary for Development, Mrs Carrie Lam, in the Legislative Council today (November 14):

Question:

It has been reported that green buildings have become very prevalent in recent years. Recently, I have also received requests from some residents of the Sha Tin District for greening the rooftops of the Sha Tin Town Hall and the Sha Tin Public Library. They pointed out that greening rooftops could beautify the environment on the one hand and provide more leisure open space on the other. Furthermore, they can help lower the room temperature in the buildings concerned, reduce energy consumption and promote environmental protection. The Government once said that the Architectural Services Department (ASD) would implement green roof projects for new government buildings as far as practicable since 2001. In this connection, will the Government inform this Council:

(a) of the number of green roof projects implemented for government buildings in Hong Kong since 2001; of the number of such projects to be carried out in the next three years;

(b) of the percentage of the number of government buildings for which green roof projects have been implemented in the total number of government buildings in Hong Kong at present; whether ASD will explore the possibility of adding green features to the rooftops of all existing government buildings, so as to benefit more people; and

(c) in order to attenuate the urban heat island effect, whether the authorities will consider including roof greening in the standard construction specifications for new government buildings, in particular cultural and recreational facilities, so as to make an extra effort for the cause of environmental protection?

Reply:

President,

Hong Kong is a densely populated place. To beautify the environment and attenuate the heat island effect, the Government has been actively promoting greening in recent years. In view of the limited space available for planting in the urban areas, we have been proactively promoting innovative greening techniques, such as roof greening, to enhance the urban environment.

My reply to the three parts of the question is as follows:

(a) From 2001 onwards, the Architectural Services Department (ASD) has, where practicable, incorporated roof greening in the design of new buildings if there is adequate usable rooftop space, after taking into account the actual conditions (such as the rooftop loading capacity, structural safety, the drainage and irrigation arrangements, and the building height). Starting from 2006, the ASD has further encouraged departments which manage existing government buildings to incorporate roof greening works into their roof refurbishment projects if the building structure, availability of rooftop space and waterproof design etc. so permit. Other works departments have also implemented roof greening works, where practicable, in appropriate building projects. As at end October 2010, a total of 159 government buildings maintained by the works departments had green roofs. In addition, the works departments are currently undertaking roof greening works at 62 government buildings (including new buildings and buildings under refurbishment). Planning and design of roof greening works for another 32 government buildings are underway for implementation within the next three years.

(b) At present, the works departments are responsible for the maintenance of some 8,500 government buildings. New buildings completed in recent years account for only a small proportion, while most buildings are at least 10 years old. About 159 of these buildings (about 2%) have green roofs. For buildings already in existence, if they require any roof refurbishment works in future, the departments concerned will consider carrying out roof greening works under the established policy, taking into account the actual circumstances and technical feasibility.

(c) As explained above, it is the current practice of the works departments concerned (e.g. ASD, Drainage Services Department and Water Supplies Department) to proactively consider incorporating roof greening features into building projects under their purview. Notwithstanding, it would be difficult to impose a mandatory requirement on all building projects to install green roofs since there may be practical and technical constraints from some of the projects. To further promote roof greening in government and private building projects, the Greening and Landscape Office (GLO) under the Development Bureau coordinates with the departments concerned in conducting research on roof greening techniques (e.g. suitable plant species and plant growth medium) and disseminating the research findings. The GLO also organises professional seminars to promote these techniques to the landscaping sector, professionals and government officers, with a view to promoting roof greening technologies by lowering the technical thresholds.

Greens dig for roof plants to beat heat
The Standard
Monday, September 05, 2011

Building owners should be given government subsidies to help them green their rooftops to make for cooler premises, Green Sense claims.

Hong Kong has just experienced one of the hottest Augusts since 1884, with a monthly mean temperature of 29.5 degrees Celsius, equaling the record set in 1990 and 1998, said president Roy Tam Hoi-pong, citing the Hong Kong Observatory.

With sunlight directly hitting rooftops, temperatures can reach up to 50 degrees, he said. But with plants on rooftops, sunlight would be absorbed instead and the temperature could drop to 30 degrees.

If the temperature is lowered on rooftops, less heat will be transmitted to the whole building. This can encourage flat owners to reduce the use of air conditioners, Green Sense said.

"The less usage of air conditioners, the less generation of heat," Tam said.

He also advised commercial building owners to install solar energy generators on their rooftops.

To reduce the generation of heat and raise public awareness of environmental protection, Green Sense also appealed to members of the public to turn off their air conditioners on September 29.

The group estimates 51,000 households supported the event last year, saving about 321 tonnes of carbon dioxide emission.

"In order to better prepare for hotter summers in future, the government needs a comprehensive policy to lower temperatures in the city. However, it is not doing enough on that," Tam said.

Commenting on the Green Sense proposal, Secretary for the Environment Edward Yau Tang-wah said the government has subsidized green roof projects in some government buildings and schools.