Thermal insulation and cost effectiveness of green-roof systems: An empirical study in Hong Kong

Hong Kong is a densely populated city with high density of skyscrapers and the population is typically concentrated on 30% of the land. The adoption of skyscrapers is therefore common to maximize its capacity. As a result, the need of open space and greenery in our built environment is thus often neglected. In recent years, many building professionals promote green-roof systems to increase green space. This paper investigates the effectiveness of using green-roof systems. Questionnaire surveys and interview discussions are conducted. It is found that the questionnaire respondents are interested in implementing green-roof systems and understanding their environmental, economical and social benefits. Three case studies are also conducted to show the effectiveness of green roofs thermal insulation. The results show that green roofs can reduce the inside temperature by up to 3.4 degrees C. However, the respondents were not willing to invest a large amount of money for green-roof systems. It is suggested that governments should take leading positions to promote green-roof systems. This paper can provide insights on the use of green roofs in Hong Kong and around the world focusing on cost effectiveness and thermal insulation effectiveness. (C) 2016 Elsevier Ltd. All rights reserved.