What's Wrong with Daylighting? Where It Goes Wrong and How Users Respond to Failure
Vaidya, P., McDougall, T., Steinbock, J., Douglas, J., and Eijadi, D. Proceedings of ACEEE Summer Study, Panel 7, Page 30, August, 2004Review by Scott Schuetter, Energy Center of Wisconsin:
The authors summarize eight cases studies of various projects that employed daylighting controls. Each project encountered issues and the authors analyze the failure mechanism and how the users coped with them. A method of failure analysis is developed and four typical failure modes are identified. Finally, a template for resolving each kind of failure is developed. The case studies covered a wide range of space types and daylighting control systems. The issues and outcomes are summarized briefly below:
- College Dining Hall: Non-dimmable ballasts were connected to dimming controls and lighting control zones were not matched correctly with daylit areas. The system was reprogrammed to be switched instead of dimming and a few lighting circuits were rewired. These issues would have been noticed much sooner if calibration had been attempted at the end of construction.
- College Classroom Building: Smaller windows were installed than were analyzed in the daylight model. Pendent light fixtures blocked daylight from entering the space and darker than expected interior finishes were selected by the interior designer. Also, photosensors were located such that they measured the indirect component of the lighting system. These issues could have been prevented by including the interior designer in the daylight evaluation. Further, the location of the photosensors should have be checked in the shop drawings.
- Office Building: A lower installed lighting power combined with dark furniture led to low light levels in the space. An overly aggressive calibration also led to numerous occupant complaints and a disabled lighting control system. This could have been avoided through education of the occupants, in order to get their buy-in.
- Office Building: The installation of an overabundance of photosensors made it impossible to perform a full calibration. Therefore, no calibration was performed and the system remained inoperational. More collaboration between the inexperienced lighting designer and controls manufacturer could have avoided this problem.
- College Classroom Building: The system responded extremely quickly to changes in exterior light levels, leading to occupant dissatisfaction. Further, dissimilar components were selected from different manufacturers, making commissioning very difficult. The system was reprogrammed to afford a slower response time.
- Retail, General Merchandise: The system was working properly for over a year. However, a new store manager decided the system made the store too dark, which he believed would hurt sales. The system as therefore disabled. This example illustrates the importance of continued education in ensuring daylight savings.
- Office Building - Existing Building Major Renovation: A photodiode type sensor was installed in an open loop control strategy. This particular photosensor was normally used to control parking lot lighting. It therefore controlled the lights off during the day and on during the night. Black tape was used to trick the photosensor into leaving the lights on, and the entire lighting circuit is manually switched off at night at the lighting panel.
- Recreation Center: Baffles and HVAC ductwork obstructed the photosensors' field of view as well reduced natural light in the space. This was a result of a lack of coordination between disciplines.
Four types of failures were identified throughout the case studies; under-dimming, over-dimming, cycling, and lights being left on overnight. These issues could have been mitigated through proper controls calibration or commissioning, better coordination between design disciplines, and more checks of the contractor shop drawings.