Roof ponds as passive heating and cooling systems: A systematic review

This paper systematically reviews literature on passive heating and cooling of buildings using roof ponds. The main aims were to gain a detailed understanding of different roof pond configurations and their performance, compare effectiveness of different roof pond variants, evaluate performance of different roof pond variants relative to other passive design techniques, explore effects of climatic conditions and various design configurations on the performance of roof ponds, and identify gaps in knowledge and data. Overall, 19 roof pond cooling and 4 roof pond heating systems were identified. This review suggests that, in some cases, roof ponds can provide year-round thermal comfort while reducing demand for active heating and cooling systems. Therefore, they can be utilized in efforts towards the goal of carbon-neutral design. Roof ponds with wet gunny bags, shaded roof ponds, ventilated roof ponds, and roof ponds with movable insulation proved to be more effective relative to other variants of roof pond cooling systems. Comparing performance relative to other passive strategies showed that, in many cases, roof pond cooling systems are about equally effective in maintaining indoor thermal comfort. Meteorological conditions, water depth, roof deck material, and thickness of the insulating panel are the main factors affecting performance of roof ponds. Several areas of weakness in the literature are identified. Future research should, among other things, provide more detailed knowledge on performance of all roof pond variants, further explore suitability of roof ponds relative to other passive design measures, examine effectiveness of roof ponds when combined with other passive design measures, analyze life-cycle costs of roof ponds, and provide more knowledge on their real-world application.