Energy Performance and Application of Green Roof Systems for Buildings in Hong Kong

Project: Research

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Description

With a well-insulated roof design, the heat gain as well as the cooling load of the air-conditioning system can be reduced. The conventional material used to construct the roof is either concrete or tile. In order to improve the thermal insulation performance of the roof, the idea of green roof is widely promoted and becoming popular in many developed cities. Green roof is a vegetated space that is structurally integrated on top of building roof. Green roof offers a number of merits such as amenity/aesthetic benefit including increased leisure and functional open space. In terms of environmental benefit, the urban heat island effect can be mitigated since the plants can offer the roof an increased building insulation, protect the buildings from solar radiation and carry out heat energy through evaporation process of the plant and soil.For assisting the building designers and engineers in designing the green roof system, computer simulation offers its high efficiency and flexibility. Moreover, under the promotion of building energy and environmental performance assessment schemes by the local government, there is a need to accurately determine the building energy efficiencies of various types of green roof system applicable to Hong Kong’s unique climate. In addition, a quantitative dataset of energy saving from green roofs should be developed for establishing a rating system. With this rating system, the potential impact of various green roof systems can be effectively revealed in the building energy and environmental assessment scheme.However, for the study on the energy performance of green roof, there are currently few design tools available to assist researchers to carry out accurate assessment of the green roof systems. Moreover there is little work that had been done for validation of the software/model for green roof systems in terms of accuracy and applicability. There is a need to verify the accuracy of the software/models in general, particularly their applicability in Hong Kong which is located in the sub-tropical region.The objectives of this project are to validate the accuracy and applicability of the existing building energy simulation programs for modeling green roof system with the measured data/results from an experimental setup. The thermal performance of various green roof systems under different climatic conditions with varying meteorological parameters including solar radiation, air temperature, relative humidity, wind speed and rainfall will be investigated. Then sensitivity test through parametric computer simulations will be carried out to identify the key design parameters with significant impact on the performance of green roof systems. A quantitative dataset of energy saving from various types of green roof systems will be established for development of a rating system. With this rating system, the potential impact of energy saving of various green roof systems can be effectively revealed in the existing building energy and environmental performance assessment schemes in Hong Kong. Moreover, through life-cycle cost and life-cycle assessment techniques, the economical and environmental performance of various green roof systems for application in Hong Kong will be investigated.

Detail(s)

Project number9041441
Grant typeGRF
StatusFinished
Effective start/end date1/01/101/11/12