Lighting and visual comfort performance of commercially available tubular daylight devices

Tubular daylight devices (TDDs) require a much smaller roof opening than conventional skylights and, because of their highly reflective tube, they can deliver farther away from the building envelope. This provide lighting energy savings, increasing resilience in new and existing buildings. Different types configurations are available amongst commercially TDDs, including domes/diffusers with varying optical properties diameter TDD. paper presents comprehensive experimental evaluation visual comfort performance multiple dome type (prismatic clear), diffuser (Fresnel prismatic), (53 35 cm), under range environmental conditions (different times day/year, sky cover). Based on illuminance measurements, estimated use is also presented. Results indicate that, for clear sky, light levels increase decreases solar altitude (e.g., 16 Wh/m2 daily intensity high maximum (MDSA) day 34 low MDSA day) TDD 69 53 cm respectively, MDSA). The profile more rounded prismatic domes has higher peaks domes; this translates into somewhat average useful (DUDI) (86 %) when compared to (80 %). No impact was apparent. Measurements indicated no discomfort glare any tested.