A review of the application of sunspace in buildings

The energy consumed by the heating, ventilation, and air conditioning (HVAC) system accounts for a large part of the energy consumption of buildings. Solar energy technologies in buildings have attracted more and more attention from scholars and architects because of their significant advantages in sustainable development, such as energy saving, environmental protection, and cost reduction. Sunspace has been studied for many years as a passive solar heating and ventilation technology. Nevertheless, there are also some problems associated with sunspace, such as overheating in summer and heat loss at night. The main objective of the work is to review the application of sunspace in buildings for heating and cooling, and possibly inspire more future works. This research adopts the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method. The novelty of this work is to categorize different types of sunspaces according to the integration relationship with buildings and different configurations, materials and functions, and further analyze all the possible factors that can affect the performance of a sunspace. This paper concludes that sunspace can be divided into ventilated and unventilated sunspace based on the main utilization methods. According to their integration relationship with buildings, sunspace can also be divided into two types: façade and roof sunspace. Based on different configurations, materials and functions, façade sunspace further includes glazed sunspace, membrane sunspace, phase change material (PCM) sunspace; and roof sunspace includes on-top sunspace, courtyard sunspace, and integrated rooftop greenhouse. There are eight factors affecting sunspace performance that are further evaluated from the perspective of energy, environment, and economy. Directions of potential studies of sunspace are suggested. The authors hope that this research will be helpful to scholars and architects and promote the development of the multifunctional sunspace system.