Hotel Survey Illuminates Energy Savings
Lighting fixtures in hotel rooms can contribute greatly to overall building energy use. The average number of fixtures per room is often five or six, and as many as half of the 15 million hotel rooms in the U.S. are still using incandescent lamps. With this in mind, researchers Erik Page and Michael Siminovitch of EETD's Building Technologies Department set out to measure how much energy could be saved with simple changes to hotelroom fixtures.
With cooperation from the Crowne Plaza in Redondo Beach, California, EETD researchers retrofitted 10 guestrooms with novel prototypical fixtures and lighting controls developed by EETD and its industry partners. The prototypes included dedicated compact fluorescent lamp table lamps and torchieres and specially designed lighting controls in the bathrooms (see Figure 2). In its standard mode, the bathroom controller operates as a simple occupancy sensor, turning off the fixture when it senses no movement. The occupancy sensor was set to an extra-long one-hour timeout so it wouldn't turn the light off if a guest was in the shower or bath for an extended period. In its "nightlight" mode, the controller allows the bathroom light to operate at 10% light output for 10 hours, or until the switch is pressed. This feature was designed as an energy-efficient option for people who want a low-level night light in their bathroom.
Lighting-use profile data from all rooms were collected for three months. Loggers recorded the times at which fixtures were turned on and off, and timers detected movement in the room with motion sensors. An analysis of the data shows that of all the fixtures, bathroom lights were operated the most at nearly eight hours a day. Since bathroom fixtures in the Redondo Beach Crown Plaza use four 60W incandescent bulbs, usage for each guestroom averages more than 600 kilowatt-hours per year, for a cost of almost $60 for each room. The next most-used fixture, bedside table lamp, burned an average of almost 5 hours per day and represent nearly 180 kilowatt-hours per year of energy consumed, at an operation cost of more than $12 per table lamp per year.
Data from the loggers, which recorded times of use, showed some surprising results. The periods of high use (mornings between 6 and 10 A.M.) and evenings (after 5:30 P.M.) were not unusual. However no significant dips in use were recorded during typical unoccupied daytime periods (11 A.M. to 5 P.M.), leading researchers to conclude that hotel staff were not instructed to turn off fixtures when leaving the rooms. Here lies another opportunity for considerable energy savings. For example, the long burning hours of the bathroom luminaire and the usage pattern found there make a strong case for occupancy sensors. While the bathroom fixtures were rarely left on for long periods, when they were, it added up to significant energy usage. The bathroom lights were left on longer than two hours only 10% of the time, but these longer burning periods account for over 75% of this fixture's energy consumption. These data point to an obvious need for an occupancy sensor. Because bathrooms are separated from the general room, the occupancy sensors are unlikely to be triggered falsely.
Further study of the energy-saving potential of occupancy sensors, including a more focused study on bathroom controls, is necessary. User acceptance must be factored into the study as well. It's important to configure energy-saving technologies such as occupancy sensors to be as transparent and unnoticeable to the users as possible. Otherwise, a possible barrier is the perception that the technologies will somehow deter from the quality of the guestroom in spite of the energy savings.
For more information, contact:
- Erik Page
- (510) 486-6435; fax (510) 486-6940
The report is available by visiting the Lighting Research Group web site.
This work was prepared for the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Building Technology, State and Community Programs, Office of Building Equipment of the U.S. Department of Energy.