Qualitative and quantitative assessment of outdoor daylight on vertical surfaces for six climate specific Indian cities

Abstract

This article deals with experimental validation of solar illuminance model for vertical plane surfaces against measured solar global illuminance at New Delhi. The paper also deals with computation of solar illuminance (daylight), both quantitatively and qualitatively, on four cardinal vertical surfaces at six Indian stations. The stations identified for the study are: New Delhi, Jodhpur, Pune, Kolkata, Shillong and Leh. Quantitative analysis of daily average solar illuminance shows that most of the stations under study receive maximum illuminance on north, east and west surfaces, during summer months of April–July, whereas the south surface receives maximum illuminance during winter months of November–February. Higher range of daily average solar illuminance on four vertical surfaces is evaluated as follows: 45–55 klx on south surface, 20–35 klx on west surface (all the stations except Pune), 20–30 klx on east (Pune) and 14–15 klx on north surface. Qualitative analysis shows that for the global illuminance in the range of 20–40 klx, for four vertical surfaces, the percentage of annual day time is: 3–8% for north surface, 25–30% for south surface, 20–30% for west surface and 20–25% for east surface.

Keywords

• sky diffuse illuminance
• daylight on vertical surface
• cumulative frequency of solar illuminance