Introduction

Green roof systems are living vegetation installed on the roofs and can provide many environmental and social benefits for achieving low carbon high performance building. They could contribute positively to make cities more liveable by providing green spaces, mitigating urban heat island (UHI) effect, reducing air quality problem, enhancing stormwater management and biodiversity. It is believed that green roofs, green/living walls, vertical greening systems and other greening methods will become an important feature in the urban landscape and can perform a vital role in helping cities adapt to the effects of climate change. This research aims to investigate the benefits of the greening systems, assess the technical issues, and develop practical information for capacity building.


(Image source: Dr Sam C M Hui)

(Image source: SIG Design & Technology, UK)
Research Areas

To investigate the performance of green roofs and vertical greening systems and determine the best strategy for designing them in Hong Kong and other urban cities, some research studies have been done on the following areas since 2002:

Green roof systems:
1. Energy and environmental performance of green roofs
2. Cooling and air quality effects of green roofs
3. Life cycle assessment of green roof systems
4. Biodiversity assessment of green roofs
5. Thermal and energy performance of green roof systems
6. Modular green roof systems
7. Stormwater mitigation of green roofs
8. Green roof urban farming
9. Integration of green roof and solar energy systems
10. Energy saving potential of green roofs

Vertical greening systems:
1. Environmental benefits of indoor living walls
2. Green noise barriers
3. Thermal regulation and energy performance of vertical greening systems
4. Evapotranspiration analysis of vertical greening systems
5. Vertical greening for underground space
6. Double skin façade with vegetation plants
7. Embodied energy and carbon for indoor living walls

The findings of the above research studies provide useful information for evaluating the effects of green roof and vertical greening systems in urban cities. Attention has been paid to applying them onto existing buildings because they constitute a major portion of the building stock. The results are very significant to ensuring sustainability of the urban environment and enhancing scientific knowledge of urban greenery.

Outlooks

Greening systems can be integrated with other sustainable technologies (such as solar photovoltaic, wind energy, and rainwater harvesting) so as to improve the environmental performance and energy balances of the building. If the conditions allow, they can also be used for rooftop farming and community gardens in order to facilitate urban agriculture, educational activities and other social functions.
   
Further research will be carried out to examine the critical issues and develop practical information for promoting a truly "sustainable" rooftop. Knowledge exchange activities will also be established to educate the stakeholders and inform the society about the importance and limitations of urban and building greening. It is believed that the building integrated greening (BIG) or building integrated vegetation (BIV) technology has a potential to improve quality of population health and welfare in the urban areas with dramatically reduced vegetation. Hopefully this will lead to a holistic green building and sustainable built environment.

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