Rule of long-wave radiation in enclosed building space

•The long-wave radiation calculation model based on direct and reflected components is established.•View factors were used to replace radiation angle coefficient.•Reveals the effect of enclosed space on long-wave radiation intensity of buildings.•Discussed the effect of different sizes of enclosed space on long-wave radiation. To study the trend of long-wave radiation in urban spaces surrounded by dense buildings, a calculation model for long-wave radiation was established. A simplified calculation of view factor was built in the model. The model of long-wave radiation formed by direct and reflected components and Kirchhoff's current law was used to calculate the reflected radiation. The accuracy of model was verified using the measured experimental data obtained from three locations in Xi'an, Sanya, and Harbin. The model was used to calculate the long-wave radiation on the external surface of a building in both enclosed and open spaces. Using the long-wave radiation model, the rule of long-wave radiation in an enclosed space was obtained by analyzing different forms of building enclosure.