BERKELEY, CA —  Lawrence Berkeley National Laboratory (Berkeley Lab) researchers are studying the energy savings of a new energy-efficient lighting control system to be installed at a DoubleTree Hotel in Sacramento, under an agreement just signed by Berkeley Lab, the Sacramento Municipal Utility District (SMUD), DoubleTree Hotels, and The Watt Stopper, Inc.

The system was based on research performed by Berkeley Lab scientists on improving hotel room energy efficiency, in collaboration with product development engineers at Watt Stopper.

The technology demonstration contract calls for the "relighting" of the entire Sacramento facility, which has more than 400 rooms, with a new control system for bathroom lighting. The Watt Stopper is manufacturing the units, and SMUD and DoubleTree are sharing the demonstration's costs.

Berkeley Lab researchers in partnership with SMUD developed the demonstration to measure and verify the energy savings, with funding from the California Energy Commission's Public Interest Energy Research (PIER) project.

Dave Bisbee of SMUD is working with Berkeley Lab on the development of this demonstration. Says Bisbee, "This project represents an outstanding partnership of different interests that will accelerate the market use of this energy-saving device."

Improving the efficiency of an efficiency-conscious industry

Several years ago, Berkeley Lab lighting researchers conducted a Department of Energy-funded study to search for ways of improving energy efficiency in the hospitality industry.

"We found that one of the largest energy-saving opportunities in hotel guestroom lighting is eliminating the unnecessary extended operation of the bathroom fixtures," says Berkeley Lab lighting researcher Michael Siminovitch. "More than 75 percent of the energy used by these fixtures occurs when they are left on for more than two hours at a time." Siminovitch and Erik Page, of Berkeley Lab's Environmental Energy Technologies Division, conducted the work.

The study showed that bathroom lights are activated for the longest periods of time in occupied hotel rooms — an average of eight hours, compared with less than five hours for bedroom lights, and two hours for desk lights.

A standard solution to lights being left on is the occupancy sensor, which automatically turn the lights out when guests leave the room. However, hotel managers were reluctant to reduce the comfort of their guests with a device that might irritate occupants by turning lights on and off when they were in the bathroom for an extended time period.

A Berkeley Lab survey of hotel room energy use showed that 75 percent of energy use occurred when the bathroom light was left on two hours or longer.

The researchers realized that they could install occupancy sensors in hotel bathrooms with long set times (one hour or more) and still get very significant energy savings, because the vast majority of energy use occurs when the fixture is left on longer than two hours when guests are gone out of the room.

"The long set time would achieve these energy savings in a manner that would be relatively transparent to the guest," says Page.

Commercializing a technology to respond to the opportunity

As a result of this study, The Watt Stopper, Inc., which manufactures automatic lighting, heating, ventilation and air conditioning, and office power control products, entered into a partnership with Berkeley Lab, SMUD, DoubleTree, and the California Energy Commission to develop a product based on this research that the hotel industry could install in its rooms and that could capture the energy savings identified by Berkeley Lab without sacrificing lighting quality.

In fact, according to Bob Hughes, regional director of the DoubleTree, the automatic night-lighting system on this device should increase the quality of the guest experience. "We are very excited about the potential of this device to save energy in a manner that will not impact guest comfort," he says.

The sensor replaces the standard wall switch in guest bathrooms. It is set to turn off the light after one hour. An energy-efficient light-emitting diode night light provides illumination, eliminating the need to leave bathroom lights on throughout the night. This LED-based night light improves the comfort of the guest for night use of the bathroom without using a bright overhead light.

Under the technology demonstration agreement, DoubleTree Hotel will install this technology in its Sacramento hotel, and the Berkeley Lab Lighting Research Group's Siminovitch and Page will analyze it.

The hotel-lighting energy research was funded by the DOE's Office of Building Technologies. The Sacramento technology demonstration and partnership is supported by the California Energy Commission's Public Interest Energy Research Program.

Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research and is managed by the University of California.

Additional information

More on lighting energy savings opportunities in hotel guestrooms