Secondary Author(s)

Parker, Danny; Floyd, David

Report Number




Energy Consumption; Buildings; Windows


Three studies were conducted at Florida Solar Energy Center (FSEC) to study the lighting energy savings of daylight dimming systems. The Daylighting Test Facility (DTF) was used to study daylight dimming systems and how aperture orientation and blinds affect performance. The energy consumption was compared in two pairs of offices for all four window orientations: north, south, east and west. One office in each pair had blinds in a fixed position (down and open) and the other office had no blinds. The study showed that the energy savings ranged from 24% to 51% depending on the orientation and blinds.

The second study conducted at the Lighting Flexible Test Facility (LFTF), compared two daylight dimming systems in identical side-by-side south facing offices. Five daylight dimming systems were tested to evaluate the system efficacy and energy reduction during daytime hours. Data on power consumption, power quality, and work-plane interior lighting levels were recorded. Daytime savings (8 AM - 5 PM) varied from 20% to 57% depending on the available daylight.

The third study, conducted at a new office facility building, studied how blinds and light shelves effect daylight dimming energy savings in offices designed for daylighting systems. Power consumption and work-plane interior lighting levels were compared in four identical south facing offices each with two spectrally selective windows. Two offices were configured with a light shelf, one with a white upper surface and the other with a reflective surface. One office had no window management strategy and the fourth office had blinds which were manually adjusted by the user. The study showed that the energy savings ranged from 33% to 53% depending on the window configuration.

Date Published



Reference Publication: Schrum, L., Parker, D., Floyd, D., "Daylight Dimming Systems: Studies in Energy Savings and Efficiency," Presented at The 1996 ACEEE Summer Study on Energy Efficiency in Buildings, Pacific Grove, CA, August 25­31, 1996.

Local Subjects

Buildings - Energy Consumption; Buildings - Windows


FSEC Energy Research Center® Collection



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