A field study of tubular daylight guidance installations.

The study reports achieved conditions and user views in 14 buildings equipped with passive zenithal tubular daylight guidance systems and electric lighting and, in some cases, windows. The daylight contribution was in the order of 35% of total design workstation illuminance giving daylight factors of between 0.5 and 1.0%. User views elicited by questionnaire suggest that tubular daylight guidance systems (TDGS) were inferior to windows in delivery of both quantity and quality of daylight. Guidelines for the design of future systems are suggested. [ABSTRACT FROM AUTHOR]