Assessing the Impact of Cloud Cover on the Availability of Daylight in Office Interiors (Case Study: Three Office Buildings in Nowshahr)

Document Type : Original Article

Authors

1 Associate Professor at Faculty of Architecture and Urbanism, Tabriz Islamic Art University

2 M.A. Graduate, Department of Architecture, Faculty of Architecture and Urban Planning, Tabriz Islamic Art University, Tabriz, Iran.

10.22080/jeem.2026.30566.1036

Abstract

Objectives: Daylight-oriented design in buildings can significantly enhance occupant satisfaction and well-being. However, fluctuations in solar radiation—particularly under cloudy or partly cloudy sky conditions—reduce indoor daylight availability and consequently increase electrical lighting demand.
Methods: To estimate the average indoor illuminance in office spaces, three office buildings located in Nowshahr—characterized by a mild and humid climate with predominantly cloudy conditions throughout the year—were modeled using Autodesk Ecotect. For the evaluation and comparison of daylight availability, fifteen identical measurement points were selected in each floor plan and analyzed under two separate simulation conditions: (1) using the official Nowshahr weather file, and (2) using simulations based solely on geographic coordinates.
Results: The simulations revealed that the average illuminance levels obtained under the first condition were lower than those in the second, confirming the influence of cloud cover on indoor daylight performance. Daylight levels were higher in proximity to the windows and decreased progressively toward deeper zones of the interior. Furthermore, upper floors received greater daylight due to the absence of surrounding external obstructions. Among windows with identical widths, those with greater height allowed significantly more daylight to enter the space.
Conclusion: The findings demonstrate that cloud cover has a notable impact on indoor daylight availability. In regions where overcast conditions predominate, reduced daylight penetration becomes particularly problematic—especially in office environments that require higher levels of illumination. Consequently, appropriate spatial design and optimal window placement play a crucial role in enhancing daylight performance and reducing reliance on electric lighting.

Keywords

Main Subjects

Files

History

  • Receive Date: 19 November 2025
  • Revise Date: 07 January 2026
  • Accept Date: 30 January 2026
  • Publish Date: 21 April 2025

Share

How to cite

Statistics