Reflectivity and specularity of building envelopes: how materiality in architecture affects human visual comfort

Highly reflective and specular building envelopes have become widely adopted not only for aesthetic reasons, but also to increase building energy savings and improve occupant comfort. However, they can also make significant and sometimes unintended impact outside the building envelope. Reflected sunlight from highly specular building envelopes can cause discomfort glare to people outside buildings. A human subject study was performed in an outdoor research setting. High dynamic range imaging was used to capture exterior glare scenes and to visualize glare sources in the field of view. Collected subjective evaluation data and captured glare scenes were statistically analysed to prove the existence of exterior glare problems. Perceptible and disturbing glare levels were experienced by the participants, and strong correlations were found between visual discomfort and excessive sunlight reflections from specular building envelopes. Exterior glare scenes were also documented in downtown Los Angeles to explore existing problems.