Savings from Daylight Harvesting Varies with Occupancy
Daylight harvesting reduces lighting energy consumption by using natural light to offset electric light in perimeter workspaces. A study of five federal buildings found that daylight harvesting provided an average annual energy savings of 27 percent.
However, the study found increased savings from occupancy control left little room for savings from daylight harvesting.
GSA’s Green Proving Ground (GPG) program commissioned Lawrence Berkeley National Laboratory to assess the performance of daylight harvesting at five federal building sites, for the report “Integrated Daylighting Systems.”
The five long-term study sites with active daylighting averaged annual energy savings of 0.84 kWh/ft2 or 27 percent. Payback ranged from 4.3 to 17.6 years, with three of the five sites realizing simple payback of less than 6 years. Two sites would have had more attractive payback if they had been occupied a larger percentage of the time—greater use resulting in greater savings.
The report recommends deploying daylighting technology where existing lighting use is high. As a rule of thumb, daylight harvesting becomes cost-effective at an installed cost of $1.40/ft2, with a utility rate equal to the national average of $0.10/kWh, assuming dimming ballasts are already in place.
- 2015 Insider Knowledge
- Four Key Questions to Ask Before Your Next Energy Purchase
- Advanced Rooftop-Unit Control (ARC) Retrofits: Field Demonstrations Validate Energy Savings
- Strategies for a Successful EHS&S Software Selection
- 2016 Energy and Sustainability Predictions Findings from Facilities Professionals
- Choosing the Correct Emission Control Technology
- Building Energy Benchmarking & Transparency Laws
- 10 Tactics of Successful Energy Managers
- Shifting the Focus from End-of-Life Recycling to Continuous Product Lifecycles
- Combined Heat and Power