Estimation of daylight availability in Kolkata and approximation of indoor daylight levels for different daylighting methods

Abstract

This work estimated the daylight availability and luminous efficacy of solar illuminance and approximated indoor daylight levels for various indoor daylighting methods for Kolkata, a major city in eastern India having tropical savanna climate, by applying two computational methods: the Perez model and the IESNA recommended calculation procedure. It was found that hourly horizontal diffuse and global illuminance, horizontal sky and total daylight illuminance values remained mostly over 10 klx throughout the year, and global and diffuse luminous efficacies mostly remained around 95–120 and 110–150 lm/W, respectively. The linear correlation between solar irradiation and estimated illuminance was stronger for Perez model. Thus, the application of Perez model was considered the better choice to appraise the daylighting potential of Kolkata.

Keywords

• daylight availability
• solar illuminance
• daylighting devices
• global luminous efficacy
• diffuse luminous efficacy