Investigating the potential of applying vertical green walls to high-rise residential buildings for energy-saving in sub-tropical region

In metropolitan cities like Hong Kong, residential buildings are mostly high-rise developments. These buildings do not have external insulation. In sub-tropical regions with mild winter heat loss from buildings in winter is insignificant and hence heat transfer from the interior of the building is low. Heating systems are rarely installed. However, heat transfer through the external façade into the interior is high in summer necessitating air-conditioning for thermal comfort and consuming large amounts of electrical energy. Vertical greenery, installed to the external walls of buildings, has been proved to be a good insulation system. This research studied the feasibility of applying a double-skin green façade, to high-rise residential buildings in Hong Kong in order to reduce energy consumption for cooling in hot and humid summer. The study concluded that substantial energy saving is possible. Further research on the application of vertical green wall systems to high-rise residential buildings is recommended.