Advanced lighting and automated window shading reduced lighting energy usage by nearly 80% in a recent test on one floor of a New York City high-rise during a recent field test.
A partnership of Lawrence Berkeley National Laboratory and the Building Energy Exchange (BEEx), the test incorporated four sets of technologies across one 40,000-square-foot floor of an office building.
The T5 fluorescent lights on the floor were replaced with dimmable LEDs, which were adjusted throughout the day to reflect changes in daylight levels and space occupancy. Researchers raised and lowered automated shades to bring in outside views, let in daylight or reduce glare.
The space was monitored for a full year before the retrofit to create a baseline for comparison, then for another six months after the retrofit.
The 40-foot-deep perimeter zone saw a 79% reduction in lighting-related energy use, and the associated demand for peak lighting was decreased by 74%. Most of the savings resulted from switching to LED lighting and allowing dimming across the entire floor rather than just next to the windows. The ability to customize zone control at the work-group level with advanced controls also contributed significantly to the savings, with many of the configuration decisions based on the need to maintain both bright interiors and access to the outdoors.
If the entire building received the same retrofit, researchers estimate a total electricity savings of $730,000 per year at an average rate of 20 cents per kWh, resulting in a 3- to 12-year payback depending on installed system costs.
“Using everything we learned on this project, we’ve developed a series of tools that will really help the engaged design professional or building owner make better decisions about lighting system upgrades and avoid the common pitfalls on the road to a high performance office space,” explains Yetsuh Frank, BEEx Managing Director of Strategy and Programs.