Regression modelling of radiant fluxes on different view factors under shading in a densely built environment

ABSTRACT

The exchange of radiant fluxes between different surfaces in an outdoor environment can be described with an enclosure theory. It provides a physical understanding of the relationship between different surfaces and consequent radiant fluxes within an enclosure, which is constructed by including surfaces of building façades and an imaginary surface of sky dome. Radiant fluxes on a surface can be expressed as linear combinations of view factors. This study examines the linear dependencies of urban radiant fluxes on view factors, namely Sunlit View Factor (SLVF), Green View Factor (GNVF), and Sky View Factor (SVF), using an empirical regression analysis. Results revealed a simple and linear correlation between view factors and outdoor radiant fluxes. As such, a quick estimation of the potential increase in the outdoor mean radiant temperature in relation to neighboring built environments can be achieved, and industry guidelines for designing thermally comfortable open spaces can be formulated accordingly.

KEYWORDS:

• Urban morphology
• radiant fluxes
• Sky View Factor (SVF)
• Sunlit View Factor (SLVF)
• Green View Factor (GNVF)

Acknowledgements

The authors are thankful to Mr Julian Lee and Ms Judy Zhang for their effort and kind help. The authors also cordially thank Mr Max Lee for setting up the equipment.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The research is made possible with financial support from the Construction Industry Council (CIC) on the project ‘A Study of Impact of Building Envelope on Urban Outdoor Thermal Environment’ (Project ID: CICR/04/13) (http://www.cic.hk/eng/main/research_data_analytics_/cic_fund_projects/).