Shading and day-lighting controls energy savings in offices with fully-Glazed façades in hot climates

Abstract

Shading devices installed on windows are designed to reduce solar radiation transmission into the space by absorbing and reflecting radiation rays. This study investigates the effect of shading and day-lighting controls when applied on fully-glazed facades on the annual energy savings in hot climates. For this reason, a dynamic simulation model of a space containing brise soleil and venetian blinds added to the façade exterior surface was developed on EnergyPlus and validated experimentally for office spaces located in Doha, Qatar. Comparison between the experimental and simulation models showed maximum discrepancies of 11.8% and 13.5% in surface temperature and peak space thermal load, respectively.

Upon validation, the simulation model was used to evaluate the annual energy savings associated with the use of shading devices on both south and north-oriented façades in Qatar. For the south-oriented façade, brise soleil and fixed blinds with 90° with the vertical were found to save 18.6% and 20.6% of the space energy demands respectively, while mitigating glare risks. As for the north façade, the addition of brise soleil and blinds saves 7.7% and 9.1% of the space total energy demands respectively and removes all risks associated with glare. The adoption of a shading control for the blind angle and day-lighting control for the electric lights was found to save 26.1% of the space total energy without compromising the comfortable glare limit. This control strategy allows the occupants to benefit from the fully-glazed façade while still upholding the indoor space requirements in terms of outdoor visual comfort and day-lighting entrance.