Performance analysis of light shelves in providing visual and thermal comfort and energy savings in residential buildings

Using light shelves (LSs) is one of the passive-enhancement methods for energy saving and providing better thermal comfort conditions of the building users. The goal of this research is to create a consistent daylight environment that improves the visual and thermal comfort of users in buildings. Comfort effects on the four fronts of a building (in the Pars residential complex of Mashhad city in Iran as a case study) are investigated. Five types of LSs are suggested for improving the building's thermal and visual conditions. Then, the illuminance analysis is performed for the building with and without the LSs. Horizontal and vertical LSs are considered in building to enhance visual quality and uniformity of daylight in the building space. According to the highest and lowest light intensity in the investigated spaces, the LS that provides optimal visual conditions for space is selected. Then, the role of optimum LS in thermal comfort and energy indicators (heating, cooling, and electricity) has been investigated and compared with the base situation. Analyzing the results reveals that using the optimal LS causes an annual average improvement of 18%, 11%, and 7% in the demand for heating, cooling, and electricity, respectively, of the building throughout the year.