ABSTRACT
Daylight utilization has been determined in a sample of 55 rooms in ten office buildings in The Netherlands with a new measurement technique. This technique shows in a cost-effective way utilization of daylight, use of artificial lighting and the presence of occupants. The energy conservation by daylight is defined as the product of the installed power for lighting and the time period that artificial lighting is switched off while occupants are present. During 12% of working hours daylight is utilized. There is some extra potential of day light use during a part of the 45% of time that occupants are present with lighting switched on. Daylight utilization can potentially increase a further 20 to 25% up to about 35% of working hours. Occupant’s attitude towards artificial lighting and day lighting is characterized by a short questionnaire. The designed rating of the answers of these questionnaires (user score) appears to explain a significant part of the utilization of daylight.
