CEC PIER Office Daylighting Study

Daylight in existing buildings represents a vast untapped resource for energy and demand savings. To quantify this potential for existing California office buildings, TRC conducted an office daylighting potential study as part of the Daylighting Plus PIER Program, funded by the California Energy Commission.



California Energy Commission

Project Location


This project estimated the demand and energy savings potential from adding photocontrols to existing daylit office spaces in California, and quantified how much further those savings could be improved with additional daylighting enhancements. The California Commercial End-Use Survey (CEUS) dataset of 536 existing office premises provided a basis for the analysis, which used Radiance-based annual daylighting simulation and a new facade-templates based methodology.

The results from the simulation exercise show that adding photocontrols to all daylit areas in office buildings existing as of 2002 within the combined IOU (Investor Owned Utilities) and SMUD territories would have a technical potential of saving 458.5 GWh of energy per year and 184.2 MW of peak demand. The results are also reported by utility and climate zone, and by building size, window to wall ratio, and control type. The average whole building energy savings calculated per square foot area of office building area, including HVAC effects and all non daylit areas.

The project also identified improvements from various daylighting enhancements such as increased interior reflectance, reduced furniture partition heights, and addition of light shelves. Building types and physical characteristics of office spaces were identified that hold the greatest potential for savings, and thus could be used to target audits or utility retrofit programs for greatest impact.

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