Effects of Shading Strategy on daylight illuminance and energy consumption for southern facades of Office Buildings

Abstract

This study investigates the effects of exterior shading strategies on annual average daylight illuminance and electricity consumption for the southern façade of a two-story office building in Ann Arbor, Michigan. Using eQUEST, four cases were simulated: a baseline without shading, horizontal overhangs only, vertical fins only, and a combination of overhangs and fins. The results show that all shading configurations reduce electricity consumption compared with the baseline, while horizontal overhangs perform more effectively than vertical fins. The combined strategy achieves the lowest annual electricity consumption and the largest reduction in daylight illuminance. However, excessive shading also reduces the hours during which daylight illuminance remains above the setpoint, increasing electric lighting demand and limiting additional energy savings. The findings indicate that shading design should balance solar heat-gain reduction and daylight availability, with parameters adjusted according to climate, orientation, material, and building conditions.