Venetian Blinds And Daylighting Control System Performance: A Case Study.pdf

This research investigates how Venetian blinds impact the effectiveness of daylighting control systems, which aim to reduce electric lighting needs by adjusting light levels based on available daylight. The study used a specialized test facility to monitor a modified closed-loop photoelectric control system in an office over a year. Key findings include:

- Daylight-to-Sensor Signal Ratio: Variations in this ratio cause inconsistent illuminance levels, leading to unreliable performance. This ratio is influenced by solar conditions and Venetian blind angle.

- Performance Analysis: With proper adjustments, the system maintained workplane illuminance at or above 90% of the design setpoint for most of the year. Discrepancies primarily stemmed from differences between actual daylight conditions and how the control system interpreted them.

- Commercial Systems vs. Prototype: Commercially available systems struggle due to improper commissioning and combining responses to both daylight and electric light into a single gain parameter. The prototype system, despite facing similar discrepancies, performed better by separating these contributions.

- Commissioning Guidelines: The study emphasizes the need for commissioning to account for fenestration system effects, as Venetian blinds significantly influence interior lighting conditions.

- Energy Savings Potential: Effective daylighting control systems could lead to substantial electricity and cooling energy savings in commercial buildings.