THE PERFORMANCE OF PHOTOCONTROL SYSTEMS UNDER DIFFERENT SHADING AND SUNLIGHT CONDITIONS

Open Access
Author:
Aljuhani, Abdulrahman Eid
Graduate Program:
Architectural Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
October 29, 2018
Committee Members:
  • Richard George Mistrick, Thesis Advisor
Keywords:
  • Critical point
  • RMSE
  • Workplane
  • Orientation
  • Calibration
  • Sensor
  • Photosensor
  • Signals
  • Shade
  • Performance
  • Condition
  • single sensor
  • Two sensor
  • Two sensor corrected
  • Dimming
  • signal to illuminance ratio
  • Photocontrol
  • Daylighting
Abstract:
A number of previous research studies were dedicated to providing guidelines to optimize locating a photosensor under different space configurations. Other researchers focused on improving photocontrol performance by reducing the effect of direct sunlight reflections on photosensors by integrating automated shades in their study models. This study aimed to verify the previous studies regarding a single closed-loop photocontrol sensor and improve the performance of the photocontrol systems. Advanced photocontrol systems, including more than one photosensor, were studied in an effort to reduce the sunlight factor that causes disagreement between sensor signals and illuminance on the workplane of the study model or to rectify the photocontrol signals and provide a more consistent photosenosr signal to workplane illuminance ratio. All photocontrol systems were investigated based on the two most critical points on the workplane of the office space by applying automated shades (shades up, halfway and down). All comparisons were performed based on two evaluation measures: root mean square error and energy savings. A higher performing system is one that delivers less root mean square error and higher energy savings. The advanced multisensor photocontrol systems were compared to a referenced single-sensor system in the proposed space (a model office). To optimize the configuration of the referenced photosensor system, several locations on the ceiling that were centered on the window were investigated for both narrow and wideband sensors according to recommendations from previous research studies. Then, the best photosensor configuration from these was compared to a photosensor location that was centered on the exterior wall. The location with better performance was selected as the single photosensor system reference condition. A symmetrical two-photosensor system was applied as a possible improvement to the single photosensor system, to accommodate conditions where one side of the room receives less daylight than the other. Since certain daylight conditions still produced higher photosensor signal to workplane illuminance ratios (S/E) than others, tests were performed to determine if the application of a third photosensor could be used to identify and correct when S/E ratios were high, and adjust these readings to better align them with the workplane illuminance. A narrow band sensor positioned to view the windows and adjacent floor area showed good correlation to the S/E ratio and was used to correct the readings from the other two photosensors. Each of the three photocontrol configurations (utilizing one, two, and three-sensors) was subject to four different windows orientations at two very different climate locations to study their performance and to address the system calibration process. This work achieved two main points: increasing the agreement between workplane illuminance and photosensor signals and boosting the energy savings by implementing a two-sensor and a corrected two-sensor system, which requires three sensors. Investigating the four main orientations (South, North, East, and West) confirmed these achievements and developed two different options (a fixed correction equation, and a correction equation derived from preferred shade and sky condition readings) to commission the corrected two-sensor system for the study space.