Effects of Fixed and Motorized Window Louvers on the Daylighting and Thermal Performance of Open-Plan Office Buildings

This study investigates the daylighting and thermal performance of open-plan office buildings with two scenarios of daylight louvers – fixed and motorized ones. Both types are for facade window applications. They redirect transmitted daylight to eliminate glare on occupants and increase daylight levels deeper in the interior space, but have significantly different daylight transmitting characteristics. In addition to daylighting, these louvers also affect solar heat gain. The tilt angle of slats in motorized louvers can be adjusted to control solar heat gain and daylight. In this study, an existing energy-efficient office building with fixed louvers is used. A combined thermal and daylighting model for a typical section of the building is developed using a simplified approach, and validated with measured data. The option of motorized louvers is then added to this model. The daylighting and thermal performance for different designs and seasons are assessed using the model. Results show that motorized louvers can effectively enhance useful solar heat gain and/or daylighting. The effect of building depth is also investigated.