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Controls: Hotel Room Automation

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Hotel room automation uses a variety of techniques to turn off lights and reduce HVAC operation when a room is unoccupied—the two biggest users of energy in limited-service motels. Because hotel and motel guests typically do not practice good energy conservation behavior when checked into a room, there is significant opportunity for the lodging industry to capture energy and other savings through automation. Based on available studies, automation products can produce a 25 to 44 percent energy savings per room and can be used in virtually any hotel or motel to varying degrees.

What Are the Options?

Hotel room automation includes a variety of products and applications that can be combined in various ways to suit a business’ specific needs.

Bathroom Lighting Occupancy Sensors

This very simple device is installed in the duplex electrical box that would normally house the bathroom’s light switch (the box must be located in the bathroom). It is similar to other wall-mounted occupancy sensors, except that versions have been developed with integrated night lights specifically for the lodging industry. These industry-specific models also are capable of longer timeout periods—up to one hour—to reduce annoying false-offs (where the sensor inappropriately turns off the lights when an occupant temporarily leaves the room). Further, short timeout periods have not been shown to benefit energy savings; studies show that 75 percent of bathroom lighting energy is consumed when the lights are left on for more than one hour.

Room-Based Occupancy Control

This category includes the widest variety of choices and applications. Both HVAC and lighting can be controlled on a full-room basis because all of the controls they use are local to the room and do not depend on connection to a whole-building automation system. Many of the products we list here are available in a wireless version (for communication to the other products involved), which can lower the cost of installation. (Note that when wireless products are used, they typically must all be from the same manufacturer.)

Digital thermostats with occupied/unoccupied modes. These thermostats differ from other commonly available energy-conserving thermostats in that they switch between the occupied and unoccupied modes based on a device that senses some indication of room occupancy, as opposed to using time-based control. Selecting the correct setback temperature in these devices is very important to minimize guest complaints. If the setback is too deep, the room will be uncomfortable for a long period after arrival of the guest; a small setback may not provide the estimated savings. These thermostats can work with packaged terminal air conditioners (PTACs—typically, the lodging industry uses units that are mounted on the wall of the room) or central cooling systems.

Lighting control. Hotel room lighting control can be easily implemented if all the lights in a room are on one circuit. However, this is typically only economically feasible in new construction. A contactor that switches the power on and off to the room’s overhead lights and to electrical outlets used for lamps can be controlled by the same occupancy sensor used for the thermostat or HVAC unit. Most existing facilities probably do not have the appropriate circuit configuration for room-based lighting control—construction cost pressures dictate that wall outlet circuits cover as many rooms as possible and that overhead lighting will be on different circuits—so it is not as widely applicable as room-based HVAC control.

Devices used to sense occupancy. These can include:

  • Passive infrared (PIR) occupancy sensors. These devices sense the heat emitted by an occupant. They are best placed on the ceiling in a location that enables the sensor to detect an occupant’s presence in as much of the room as possible to reduce the possibility of false-offs. A version is available that looks like a smoke detector (Figure 1), purportedly to reduce the chance that an occupant might try to defeat the device. Models that are integrated into the thermostat are also available, though this design may reduce the sensor’s coverage and accuracy.
Figure 1: Occupancy sensor in disguise

Figure 1: Occupancy sensor in disguise

Because this occupancy sensor looks like a smoke detector, room occupants are less likely to attempt to override it—in fact, they may not even realize it’s there.

  • Wall-mounted key card switches. These devices, mounted within the room, activate when the room’s door key card is inserted. They are simpler and less expensive than a PIR occupancy sensor and do not have any potential for false-offs. However, occupants can override them by leaving a second room key in the switch, thereby defeating their purpose. Further, the predominantly available switches cannot detect the difference between a room key and any other card of similar size.
  • Entry lock switches. These switches are integrated into the entry lock, so they must be compatible with the lock itself. They are also only available with wireless communications (to the thermostat made by the same manufacturer). Therefore, this technology is not as widely available as some of the others. And because it cannot tell whether only one or all of the room’s occupants have left, it is prone to false-offs. In fact, some manufacturers of this technology recommend that entry lock switches be used in addition to a PIR occupancy sensor to improve operation (which will reduce the number of false-offs that either device alone would be prone to).

Other devices used to supplement those room control options include:

  • Window or patio door switches. These switches sense whether a window or patio door is open and can be used to turn off the HVAC system or switch the thermostat to unoccupied mode.
  • PTAC interfaces. The controls within a PTAC are difficult to connect to a room thermostat. However, outboard modules are available that install between the PTAC’s power plug and the power receptacle. Because those modules communicate wirelessly with the thermostat, they eliminate the need for costly wiring (the inaccessible ceiling space typical of lodging construction makes it very difficult to run wire in an existing room). The disadvantage is that the module cannot switch the PTAC between fan, heating, and cooling modes, so can only be used to interrupt power to the PTAC when it is providing more heat or cooling to the room than is necessary. There is also a module that communicates wirelessly with a matching PIR occupancy sensor, thereby eliminating the need for, and cost of, a thermostat. The disadvantage of this approach is that there is no setback mode—the module just turns the PTAC off when the room is unoccupied.

Building Automation–Based Room Control

Due to the size of larger hotels and the presence of more common space, conference rooms, offices, restaurants, etc., these facilities can use general-purpose building automation systems (BASs) to control HVAC and lighting. These systems can be extended into the room to provide the same functions as room-based controls. When a BAS is present, or planned for in new construction, it makes implementation of the following more feasible.

  • Front desk check-in system integration for detecting room occupancy. The room HVAC and lighting can be switched to the occupied mode when a guest is checked in at the front desk. This technology involves a software interface that allows the check-in system to send a message to the BAS whenever a room is purchased. The advantages of this approach is that it eliminates false-offs, gives the room HVAC system a longer time to reach comfortable conditions, and there are fewer room-level devices to maintain. The disadvantage is that it does not save as much energy as room-based controls because the room is in the occupied mode as long as the guest is checked in.
  • Room-control monitoring. The conditions and operation of a room can be viewed from the BAS workstation. Energy usage can also be monitored to keep track of the system’s effectiveness, which also might help the lodging site’s staff make other changes or additions to the room control.

If a BAS is not already present, it would be difficult to cost-justify installing one just for room control. In addition to the cost of installing some room-based components, there would be the costs of the BAS itself, the installation of communications wiring, and the front-desk integration software, the sum of which would likely prove prohibitive to implementing this option.

Manual Control

This approach does not use automation technology, but nevertheless can be a very useful tool for hotel room energy conservation. It involves training the housekeeping staff turn off lights and set the HVAC system to an unoccupied setting. Many hospitality businesses list this technique as one of their energy conservation strategies. Unfortunately, there are no data available concerning its effectiveness versus the automation technology discussed above, and it has the disadvantage of requiring extensive and ongoing training efforts.

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How to Make the Best Choice

The decisions of whether automation is appropriate for a given hotel site and what the optimum collection of components and strategies would be requires a fairly complex analysis that is best left to an engineer or other energy professional (major hospitality companies often have someone on staff who is a Certified Energy Manager that could do this). This professional needs to have the experience and expertise to:

  • Determine how much HVAC and lighting energy is used by the rooms alone,
  • Determine how much of this energy can be saved by the various techniques available,
  • Combine the strategies together into a system and determine the energy the system will save,
  • Develop a cost estimate for the system, and
  • Calculate the financial criteria needed to economically justify the system.

The cost of implementation can range widely because hotel room automation includes a variety of applications (for example, control for HVAC or lighting, or both), as well as technologies (such as determining room occupancy based on an occupancy sensor versus activation of the entry door lock). The chosen level of automation can range from something as simple as a wall-mounted occupancy sensor for controlling the bathroom lights to a sophisticated system that includes patio-door and window switches, room occupancy sensors, and a digital setback thermostat, or even as far as a system in which automation devices are networked to the front desk check-in system. Taking all of that into account, though, paybacks of as low as two years can be achieved with the proper mix of components, according to two hotel energy managers we spoke with. Table 1 provides cost estimates we obtained from several sources.

Table 1: How much does it cost to equip a room?

Table 1: How much does it cost to equip a room?

Because there are many ways to implement hotel automation, the cost will vary based on the exact components used as well as on number of rooms and the layout of the hotel. The total room estimates include the costs of the packaged terminal air-conditioner controller, occupancy sensor, optional door switches, and—for the networked room—networking hardware.

Though independent data are limited, there are a few sources of information that can provide a sense of the potential energy savings from hotel room automation. Table 2 provides data from several studies that show that whole-room savings can range from 25 to 44 percent. In addition, two other sources provide information on the annual energy use baseline for hotel rooms, which can be helpful in estimating the total dollar or kilowatt-hour savings potential. One of these, an evaluation by Florida Power of typical annual hotel room electrical energy usage showed a baseline cost of $400. The other, an evaluation of a heat pump installation at an inn produced an annual hotel room energy use baseline estimate of 9.5 kilowatt-hours per square foot.

Table 2: How much can hotel room automation save?

Table 2: How much can hotel room automation save?

Whole-room energy savings can range from 25 to 44 percent, according to the studies we found. See the text for the full study citations.

For more information about the studies we cited in Table 2:

Note that hotel room automation implemented in a limited-service motel will have a far greater impact on the site’s overall energy usage than that for a full-service hotel. This is due to the fact that room energy usage makes up a smaller percentage of overall usage for hotels that include a restaurant, conference facilities, indoor pools or gymnasiums, and large lobby or common areas.

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What’s on the Horizon?

There are several reasons to expect that hotel room automation will become more accepted in new lodging construction projects as well as in renovations or retrofits. These include:

  • The widespread expectation that there will be continuing increases in the cost of energy.
  • The recent availability of a variety of control products specific to the lodging industry that are priced to make their application economical.
  • The growing number of groups that are promoting energy efficiency and other green practices, including lodging industry groups such as the “Green” Hotels Association and programs such as the U.S. Environmental Protection Agency’s Energy Star for Hospitality.
  • The public’s increasing concern about climate change, as well as its increasing awareness of the benefits of green design and sustainable building practices.
  • The number of large hotel chains that have announced ambitious plans for implementing energy conservation projects at their facilities, as shown through the success stories on the Energy Star for Hospitality site.

There is also the possibility that emerging technologies may become viable for the lodging industry. For example, RFID (radio frequency identification) technology may eventually be used for room entry. This could provide other benefits:

  • The system could detect the presence of occupants well before they arrive at their room (which would give the HVAC system a head start on bringing the room to the occupied comfort levels).
  • Personalized RFID cards might be made available to guests who frequent a specific chain. These cards could include information such as each guest_s preferred room temperature setpoint and lighting level.

Who Are the Manufacturers?

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Copyright 2006 - Platts, a Division of The McGraw-Hill Companies, Inc.