Managing Energy Costs in Hotels and Motels
Hotels and motels in the U.S. use an average of 12 kilowatt-hours (kWh) of electricity and 41 cubic feet of natural gas per square foot (ft2) annually. Most of the electricity these facilities consume is used for space cooling and lighting (Figure 1); typically, space heating represents their largest use of natural gas. Hotel and motel energy use will vary depending on the types of amenities available.
In order to better manage your building's energy costs, it helps to understand how you are charged for energy. Most utilities charge commercial buildings for natural gas based on the amount of energy delivered. Electricity, on the other hand, can be charged based on two measures: consumption and demand (Figure 2). The consumption component of the bill is based on the amount of electricity (in kWh) that the building consumes during a month. The demand component is the peak demand (in kilowatts) occurring within the month or, for some utilities, during the previous 12 months. Demand charges can range from a few dollars per kilowatt-month to more than $20 per kilowatt-month. Because it can be a considerable percentage of your bill, you should take care to reduce peak demand whenever possible. As you read the following energy cost-management recommendations, keep in mind how each one will affect both your consumption and your demand.
All of the conservation measures discussed here, whether for short term or longer term, represent good investments. Most will not only save money but also ensure the comfort of your facility’s guests and staff.
Many hotels and motels can benefit from quick low-cost or no-cost solutions for saving energy in various parts of their operations.
Peripheral and back rooms. Make sure that HVAC settings in lobbies, offices, and other such peripheral rooms are at minimum settings during hours of low use.
Laundry. Set laundry hot water temperatures to 120° Fahrenheit. This is a good temperature for all hot water uses outside of the kitchen, where codes are specific about water temperature.
Pools and hot tubs. Make sure that all pools and hot tubs are covered after hours to diminish heat loss. Covering a heated pool can save 50 to 70 percent of the pool’s energy use, 30 to 50 percent of its makeup water, and 35 to 60 percent of its chemicals.
Housekeeping procedures. Encourage housekeepers to turn off all lights and set temperatures to minimum levels after cleaning each room. Closing drapes when a room is unoccupied will reduce heat gain in the summer and heat loss in the winter.
Kitchen and food prep. In the kitchen, food preparation equipment should not be turned on for preheating more than 15 minutes before it is needed; simply reducing the operating time of kitchen appliances can cut cooking-related energy consumption by up to 60 percent.
Bathrooms and fitness rooms. Use automatic faucet shutoff, single-temperature fittings, and low-flow showerheads with pause control to reduce hot water waste in bathrooms and fitness rooms.
Front desk. Teach registration staff that they can help save energy costs by booking rooms in clusters, so that only occupied building areas or wings need to be heated or cooled to guest comfort levels. Rooms on top floors, at building corners, and facing west (in summer) or north (in winter) can be the most energy-intensive to heat or cool; therefore, consider renting them last.
Computers and office equipment. For hotel office spaces, a computer monitor can use two-thirds of the total energy of a desktop system, so it is important to power down monitors whenever they are not in use. The Energy Star Power Management program provides free software that can automatically place active monitors and computers into a low-power sleep mode through a local area network. Whole-computer power management can save $15 to $45 annually per desktop computer; managing only monitors can save $10 to $30 per monitor annually.
Hallway lighting. If hallways have skylights or other natural light and your lighting has dimming capabilities, dim those lights by 30 percent during daytime hours.
Guest service options. Some lodging facilities offer guests the option of forgoing daily linen changes or nightly turndown service. Some guests may not perceive a need for daily sheet and towel replacement or for lights, radios, or televisions to be turned on for them when they are not in the room.
Longer-term energy-saving strategies should also be considered. Although the actions covered in this section require more extensive implementation, they can dramatically increase the efficiency of your facility without compromising the hospitality environment. Ask your local utility's representative for more information about initiating such projects.
Commissioning is a process during which engineers observe a building and perform a “tune-up” to ensure that its systems are operating efficiently and as intended. Commissioning typically takes place when a facility is first built; however, if a building has never been commissioned, then it is ripe for retrocommissioning, which entails a similar tune-up on an existing building. All buildings also stand to benefit from regular recommissioning, which can then take place periodically throughout a building's life.
Studies have shown that commissioning can save a typical 100,000-ft2 hotel 10 to 15 percent of its energy costs, or roughly $20,000 per year. Savings typically result from resetting existing controls to reduce HVAC waste while maintaining or even increasing comfort levels for occupants. A hotel should be recommissioned every three to five years to maintain optimal performance. The precise timing will vary depending on the timing of changes in the facility’s use, the quality and schedule of preventive maintenance activities, and the frequency of operational problems. Commissioning should also be performed after major remodels or additions.
A variety of light sources can be used to provide efficient lighting throughout hotel or motel operations.
Daylighting. Natural daylight has been shown to improve a hotel’s indoor environment while reducing energy use and peak demand. Whenever possible, any lighting renovation should start by using daylighting as much as possible and reducing electric lighting accordingly. Good daylighting design will not introduce excessive heat gain, heat loss, glare, or uneven illumination. Daylighting controls in lobbies can improve lighting quality while reducing energy costs. Hotels have also used clerestories and tubular skylights to provide daylighting in hallways, lobbies, and guest rooms.
T8 fluorescent lamps. In back-room areas such as kitchens and office space, lighting fixtures using T12 (12/8-inch diameter tubes) and older T8 (1-inch diameter tubes) fluorescent lamps and ballasts can be replaced with high-performance T8 lamps and electronic ballasts, a combination that can reduce lighting energy consumption by 35 percent. Adding specular reflectors, new lenses, and occupancy sensors or timers to a T8 fluorescent lighting system can double the savings. Paybacks of one to three years are common.
Compact fluorescent lamps (CFLs). In guest rooms, CFLs are becoming the standard for table, floor, and reading lamps, and in recessed and vanity lighting in the bathroom. CFLs reduce energy use by two-thirds and yield savings of up to $20 per lamp per year. Many hotel public areas, including corridors and hallways, can use CFLs in wall sconces and in recessed downlights. During renovations or when buying new table or floor lamps, consider fixtures designed to accept only CFLs so that maintenance staff cannot accidentally relamp them with incandescents.
Light-emitting diodes (LEDs). In restaurants and lounges, LEDs (light-emitting diodes) are frequently used to create specialized lighting effects. LEDs can also provide an accent to exterior arch elements and facades and can serve as nightlights in guest rooms. Using LED exit signs is also a proven energy- and labor-saving measure that can pay for itself in one year.
Outdoor lighting. For parking lots and outdoor applications, any incandescent or mercury vapor lighting should be replaced with something more efficient. High-pressure sodium and metal halide are the most common choices, but fluorescent lighting is often a more efficient option. In parking garages, which often use inefficient high-intensity discharge fixtures, high-efficacy fluorescent fixtures can provide more even illumination with fewer fixtures. Fluorescent lamps should be enclosed when used outdoors in cold climates. Induction lamps are another possibility—they boast a very long life and are a good choice in hard-to-access areas. LEDs are also becoming a viable option, although they are currently expensive and will not be cost-effective for many applications.
It's also important to avoid over-lighting outdoor areas. Most parking lots are designed with far more lighting than the Illuminating Engineering Society of North America's Lighting Handbook (2000) recommends—that is, an average of 1 foot-candle or less for most applications. Using lower-wattage bulbs can actually increase the safety of your lot: An over-lit lot can be dangerous to drivers if their eyes cannot adjust quickly enough in the transition from highly lit to dark areas.
Lighting controls. Controls—typically occupancy sensors and scheduling systems—can also reduce lighting energy use. Occupancy sensors save energy and also help to reduce maintenance costs by lengthening the relamping interval. Turning fluorescent lights off for 12 hours each day can extend their expected calendar life by 75 percent, to nearly seven years. In large restrooms, ceiling-mounted ultrasonic occupancy sensors detect occupants around partitions and corners. For hallways, a recommended strategy is to use a combination of scheduled lighting and dimming plus occupancy-sensor controls after hours. Guests may not like a totally darkened hallway, but dimming lights in unoccupied hallways and stairwells and then turning them up to full brightness when someone enters is a sensible approach. Occupancy sensors are also appropriate for meeting rooms and back rooms.
Water heating is a major load for hotels and motels, accounting for a third or more of a facility's energy consumption. Commercial heat pump water heaters (HPWHs) are two to four times more efficient than conventional water heaters, while also providing space-cooling capacity. In fact, they can cut water heating costs up to 50 percent. However, before deciding to use an HPWH, it is important to do a careful economic analysis—they are more expensive than conventional water heaters, and their performance varies with climate. Direct-vent, sealed-combustion condensing water heaters and boilers with efficiencies higher than 90 percent are the next-most-efficient option. Unlike traditional water heaters, condensing boilers operate very efficiently during periods of low water demand, and they can also provide space heating. In general, installing multiple smaller water heaters provides better reliability, effectiveness, and efficiency compared to using one large water heater.
Hotels and motels can also use HVAC, shower, or laundry room heat-recovery systems to cut hot water expenditures. Hotels can obtain "free" hot water from their cooling and refrigeration equipment by using double-bundled heat exchangers in the chillers or a plate heat exchanger in the condenser-cooling loop. Gray water heat-recovery equipment used with showers saves 50 to 60 percent of water-heating energy with payback in two years. They also double or triple the first-hour capacity of water heaters. In addition, installing a variable-speed drive (VSD) on the hot water pumping systems will reduce pumping energy during periods of low hot water use.
In the hotel kitchen, low-flow pre-rinse spray valves are one of the easiest and most cost-effective energy-saving measures available. These devices use a spray of water to remove food waste from dishes prior to cleaning in a dishwasher. They reduce water consumption, water heating energy, and sewer charges. Look for models with a flow rate of 1.6 gallons per minute or less.
Several options are available for hotel laundry operations. New efficient tunnel washers can reduce costs through labor and utility savings. Ozone laundering systems offer big savings by using cooler water and much less of it; they also use less energy and detergent.
For hotel swimming pools, indoor pool covers typically yield paybacks of one year; covers for heated outdoor pools and hot tubs may yield even better savings. Indoor pools require simultaneous heating and dehumidification, and HPWHs can efficiently serve both of these needs: They heat water while producing cool, dehumidified air for the room housing the pool. Using an HPWH can reduce heating costs for gas- and electricity-heated pools as much as 40 and 80 percent, respectively. Low-temperature unglazed solar water heaters are an inexpensive approach that is well-suited to swimming pools and spas in warmer climates. Glazed flat-plate collectors can provide higher-temperature water.
Outside the hotel, awnings, overhangs, light shelves, and windows with low solar heat gain coefficient (SHGC) help to reduce the amount of solar heat that comes in while still allowing daylight through. Light-colored roofing materials not only reduce cooling energy consumption by 25 to 65 percent during the summer, they also extend roof life. Green roofs planted with grass and other vegetation provide excellent insulating properties, prolong roof life, reduce storm-water runoff, and offer an aesthetic appeal that could be valuable to a hotel or motel property. However, green roofs are expensive and their cost-effectiveness is still being evaluated.
Retrofitting with new, high-performance windows can be prohibitively expensive, but installing reflective film inside existing windows can be a more cost-effective option for reducing solar heat gain while still admitting useful visible light, resulting in payback periods of less than three years. Other window coverings such as shutters, shades, and draperies provide insulation benefits. This is especially true in summer months, when they reduce the amount of sunlight and heat entering rooms.
For lobby areas, revolving doors are the best choice for keeping wind and weather out. Check these doors periodically to ensure that there are no leaks along their edges or bottoms.
Dehumidification. Mold and mildew damage to wallpaper, carpet, and other materials caused by high humidity levels are big problems in the lodging industry. Causes include leaks in the building envelope in humid areas, oversized HVAC systems, poorly balanced air-handling systems, and insufficient moisture-removal capacity of vapor-compression HVAC systems. Desiccant HVAC and dehumidification systems lower humidity levels, improve indoor air quality, and increase building occupant comfort. Desiccant systems have low maintenance costs and can use a variety of fuels (waste heat, natural gas, or solar thermal energy) to lower peak electric demand, yet they may still be more expensive to operate than traditional HVAC systems, depending on local utility rates.
Ventilation controls. Hotels can use outdoor-air economizers with air-handling units so that outdoor air can be used for free cooling during spring and fall or on cool summer nights when the humidity level is not too high. In meeting rooms and other areas with variable occupancy, demand-controlled ventilation (DCV) systems can be used to reduce outdoor-air flows and the associated energy consumption during periods of low occupancy. DCV is most cost-effective for facilities located in a moderate to extreme heating or cooling climate and where existing HVAC systems do not use 100 percent outdoor air (such as those with evaporative cooling systems). Large hotel casino facilities, which have very high ventilation demands, can use heat-recovery or energy-recovery ventilators that have balanced exhaust and supply fans and can meet all ventilation needs without creating drafts and air-pressure imbalances. Heat-recovery ventilators can feature efficiencies as high as 85 to 95 percent and can pay for themselves in roughly 3.5 years. Consider these units whenever air is continuously exhausted and makeup or ventilation air is required.
A number of hotel systems can use VSDs, including variable air-volume systems, where a VSD can adjust fan speeds according to operating requirements at different times of the day. VSDs should be installed on cooling-tower fans, continuously operating circulation pumps, and any constant-speed fans that only meet partial loads (for example, fans controlled with dampers). In kitchens, for example, fans can be linked to burners to reduce energy consumption during off-peak cooking periods. Be careful, however, not to cut exhaust to the point that kitchen odors permeate other areas of the facility.
Energy management systems. Hotel studies have shown that sold rooms are unoccupied for 12 or more hours per day. Hotel operators can link their energy management system (EMS), reservation system, and automated check-out system together to keep an unsold room ventilated but with minimal heating or cooling. A sold room can then be heated or cooled to a comfortable temperature an hour before a guest's scheduled arrival. Once the guests arrive in the room, they can then adjust the temperature as they like until they check out, when the HVAC system returns to the unsold mode. An EMS can enhance guest comfort while reducing energy costs by 35 to 45 percent, for a return on investment of 50 to 75 percent. Keycards that shut off all, or most, power-consuming devices when a guest leaves a room can also help reduce guest-room energy consumption.
A simple way to ensure that purchased equipment is energy efficient is for the corporate office to request that hotel purchasing departments or franchisees specify products that are Energy Star qualified in their contracts or purchase orders. Additionally, the product recommendations for federal government procurement officials from the U.S. Department of Energy's Federal Energy Management Program may be appropriate for items not covered under the Energy Star program. Energy Star–qualified products that are relevant for hotels and motels include: commercial refrigerators and freezers; commercial fryers; commercial steam cookers; televisions, DVD players, and audio equipment; computers and monitors; printers, fax machines, mailing machines, and scanners; copiers; and vending machines.
Because vending machines operate continuously, one refrigerated vending machine can consume 2,500 to 4,400 kWh annually, and this can cost up to $440 per machine per year. The VendingMiser is a control device that turns off vending-machine refrigeration and lighting when nobody is near and when temperature levels are low enough that refrigeration is not needed. VendingMiser has resulted in vending-machine energy savings ranging from 24 to 76 percent, with paybacks of less than three years.
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