Hong Kong is an urban jungle of high-rise buildings with precious few green areas because of its dense population and limited open spaces. However, major urban centres in Europe and Japan have demonstrated how rooftop areas can be used to bring greenery into the heart of the busiest of cities and CLP Power Hong Kong (CLP) has drawn inspiration from their example.
One of the core values of CLP is caring for the environment. The company in 2006 teamed up with University to pioneer a study on Sky Woodland at rooftop of power substation that would be the first of its kind in the city.
By carefully reviewing study results and working out a formula that would best suit Hong Kong, the largest Sky Woodland in the city was opened at the Chui Ling Road Substation in Tseung Kwan O in May 2013. It is an initiative that benefits the community and the environment by enriching native biodiversity.
CLP's hope is that the success of the Sky Woodland project will generate interest and discussion among other businesses and utilities, and provide a blueprint for future rooftop greening projects across Hong Kong to make our city greener and heighten environmental awareness.
Upper Sky Woodland
Lower Sky Woodland
Climbing Plants
Vertical Greening
Wall
1
The CLP Chui Ling Road Substation in Tseung Kwan O is close to a number of major residential areas, tertiary institutions and community facilities. The Sky Woodland has been planted on the rooftops of two substation blocks, covering areas of 520m2 together with 500m2 of vertical greening on the substation walls. The Sky Woodland is home
to 80 trees made up of 32 native species and is the largest project of its kind in Hong Kong.
The Sky Woodland is far more than just a rare stretch of urban greenery. It is a slice of genuine woodland in the heart of the city, replicating a natural woodland environment that nourishes wildlife and enriches native biodiversity. In the two years since its launch, it has attracted an abundance of birds and insects and serves as a habitat, offering food and shelter to wildlife and bringing life and beauty to the city skyline it has transformed.
Indigenous species were chosen for the Sky Woodland as they adapt better to local climate and environment. A special emphasis was put on species that are related to the city, such as Bauhinia x blakeana, Hong Kong's floral emblem, Aquilaria sinensis which shares a significant relationship with the name of Hong Kong, and Rhodoleia championii, an indigenous species with a high conservation value.
CLP specially selected colourful species such as Liquidambar formosana and Elaeocarpus decipiens while designing the Sky Woodland to showcase the beauty of nature in different seasons and to beautify the surrounding environment.
Aquilaria sinensis was once widely grown in Hong Kong to make incense and medicine for exporting to the mainland and overseas. "Hong Kong" is said to be originated from the Chinese character "Hong" (incense).
Myrica rubra is a food source for birds. Its root nodules system also provides nutrients that help the growth of surrounding plants.As well as its ecological benefits, dead leaves in the Sky Woodland decomposed when they wither away, releasing nutrients for the trees and forest life cycle. The Sky Woodland is beneficial to air quality in the community, enhancing buildings' energy efficiency by reducing the indoor and outdoor temperature through solar heat absorption and transpiration*. The air and soil layers provide effective insulation and stop the buildings being exposed to direct sunlight. They also prolong the lifespan of the buildings' waterproofing layer by 10 to 20 years and reduce maintenance costs by protecting the structure of the rooftops.
Wisteria sinensis on substation wall helps absorb air pollutants.The leaves of Liquidambar formosana
2 turn yellow and red in the autumn.
*Transpiration is a biological process by which water loses from a plant through pores on leaves.
From the moment the idea for the Sky Woodland was conceived, CLP liaised closely with stakeholders to discuss the appearance and design of the substation and the tree species to be planted. Meetings were held and advice sought from government departments, district council members, tree experts and local residents to make sure the project carefully balanced the area's different needs and interests.
The Challenges in Creating the Sky Woodland
CLP took careful measures to ensure that the Sky Woodland with its 80 trees could flourish healthily on the rooftops of the substation without in any way affecting the power supply and the safe operation of the substation.
Hong Kong has a subtropical climate with seasonal rainstorms and typhoons. All the trees in the Sky Woodland were therefore planted closely together in locations that best suit their natural characteristics with height and growth cycles considered to maximise their wind resistance.
Medium-sized trees were planted in the centre of the rooftop while smaller ones were placed on the outside.
The soil on the rooftops is about one metre in depth, providing excellent drainage and waterproofing while preventing flooding and mosquito breeding. Small to medium sized trees, which are shorter than
10 metres in height with a slow growth rate, are suitable to the rooftop setting. Root barriers are installed to prevent over growing roots from damaging the buildings' structure.
CLP carefully considered maintenance and management issues during the design stage of the Sky Woodland. Suitable species were collected and grown in a nursery for more than two years before being moved to the rooftops when the substation was completed.
To ensure a smooth and fast tree loading process, the team planned well ahead in every aspect including transportation and planting to make sure the trees were in good condition and could adapt well to the rooftop environment with only minimal maintenance.
To make the substation operate in a greener way, automated irrigation systems have been put in place, collecting rainwater for irrigation. Evaporation is minimised by the planting of Ophiopogon japonicas in the woodland. The substation makes good use of natural ventilation and natural light to save on power consumption through lighting and ventilation.
Solar panels have also been installed to power the irrigation system with renewable energy.
3
Key MilestonesDate | Incident |
December 2006 | CLP teams up with the University of Hong Kong and begins studying and testing out the Sky Woodland concept |
May 2008 | Trial planting is carried out on the rooftop of the Sham Mong Road Substation in Lai Chi Kok to collect experiment data |
December 2010 | The Sky Woodland project is drafted for the Chui Ling Road Substation in Tseung Kwan O and an extensive community consultation gets under way |
January 2011 | Design work begins along with the collection of suitable trees |
July 2012 | Construction of the substation starts |
April 2013 | Planting begins |
May 2013 | The Sky Woodland is formally commissioned |
October 2013 | The Chui Ling Road Substation wins the Gold Award at the Asian Power Awards 2013 |
2015 | The Sky Woodland continues to flourish and grow healthily |
CLP Power Hong Kong Limited
Public Affairs
September 2015
4
楓香
Liquidambar formosana五月茶
Antidesma bunius廣寧油茶
Camellia semiserrata黧蒴錐
Castanopsis fissa大頭茶
Gordonia axillaris土沉香
Aquilaria sinensis郎傘樹
Ardisia hanceana水翁
Cleistocalyx nervosum陰香
Cinnamomum burmannii女貞
Ligustrum Iucidum洋紫荊
Bauhinia x blakeana大苞山茶
Camellia granthamiana黃牛木
Cratoxylum cochinchinense杜英
Elaeocarpus decipiens潺槁樹
Litsea glutinosa5
絨毛潤楠
Machilus. velutina短序潤楠
Machilus breviflora厚斗柯
Lithocarpus elizabethae餘甘子
Phyllanthus emblica檵木
Loropetalum chinense豆梨
Pyrus calleryana楊梅
Myrica rubra腺葉桂櫻
Prunus phaeosticta梭羅樹
Reevesia thyrsoidea紅花荷
Rhodoleia championii山烏桕
Sapium discolor鴨腳木
Schefflera heptaphylla木荷
Schima superba鳥桕
Sapium sebiferum6
假蘋婆
Sterculia lanceolata海南蒲桃
Syzygium cumini珊瑚樹
Viburnum odoratisimum7
distributed by |