Energy saving potential of green roofs in university buildings

Green roofs are living vegetation installed on roofs and can provide many environmental, economic and social benefits to the community. In recent years, green roofs have rapidly become a key green development tool and design features in many urban cities in the world and have been widely applied in academic institutions. This research aims to assess the energy saving potential of green roofs in university buildings and investigate the practical issues for the implementation. A field study was conducted to examine the buildings at the University of Hong Kong and evaluate the major factors and issues for green roof application. Building energy models were set up on EnergyPlus simulation software to analyze the thermal performance and energy saving potential of the green roofs. Usually, integrating green roofs into new buildings has less problems to handle. However, as existing buildings constitute a major portion of the building stock in the university campus, it is essential to develop green roofs for retrofit projects to achieve a larger impact. It is found that buildings with a higher air-conditioning demand and poor thermal insulation can benefit more from green roof in energy and economic aspects. Most energy savings come from cooling demand reduction in summer. The energy saving potential is affected by the building function, green roof type, leaf area density, plant height, irrigation rate and maintenance