NATIONAL REPORT—There was a time when energy efficiency was not a high priority when shopping for new PTACs. Today, with energy prices where they are, that has all changed. An educated buyer now considers not only unit size and heating and cooling capability, but also a model’s energy efficiency rating (EER).
“EER is a calculation that measures how much cooling you get for a watt of electricity,” says Jane Deming, manager, marketing services for Friedrich Air Conditioning, San Antonio, Texas. “The higher the EER, the better. The benefits to the hotel owner are in controlling energy consumption costs.”
Mel Harris, PTAC business development manager for LG Electronics Inc., Englewood, N.J., says the base line level is 10.0 for an energy efficient product. Lodging industry vendors sell units with up to 12.7 EER. PTACs can be purchased in sizes ranging from 7,000 BTU/h to 15,000 BTU/h. A 7,000 BTU/h unit is more energy efficient than a 15,000 BTU/h model. The more air that needs to be moved, the more energy it takes. What makes a PTAC efficient is the motor and compressor.
Harris says the formula to follow when determining PTAC size is 30 BTU/h per square foot. If, for example, a guestroom is 300 square feet, one would need a 9,000-BTU/h unit. It is always better to err on the smaller size.
“Mold can be a big problem for an owner and a guest,” Harris says. “If a unit is oversized, it will cool the air in the room quickly but then shut off. It will not run long enough to remove the moisture. You want the unit to gradually cool the air.”
When considering what size PTAC to purchase, also consider the heat load of the room. A west facing building side may need a stronger unit because of the sun’s heat. Corner rooms, hallways and rooms on upper floors also may require units with more BTUs. A PTAC has to be strong enough to handle not only natural humidity but also that created by guests using hot water in bathrooms.
Another important decision to make when considering what type of PTAC to purchase is whether to go with a model that uses electric heat or a heat pump. Tom Guffey, vice president of sales for Amana’s PTAC division, a part of Houston-based Goodman Co. L.P., says his company tries to guide customers toward heat pumps.
“Heat pumps can cut electricity consumption by two-thirds,” Guffey says.
Deming says hoteliers should look for a PTAC that provides the ability to set temperature limits. The ability to interface with an energy management system (EMS), property management system (PMS) and wall thermostat are also factors to consider. PTACs connected to an EMS or PMS can be shut down for periods of time when the guest is not in the room—saving energy and money. Mechanical units, while still cost-effective, may not always integrate with an EMS, PMS or wall thermostat.
“If a hotelier is considering an EMS, ensure that the PTAC has electronic controls in order to interface with the EMS,” Harris says. “When deciding on an EMS, first sit down and do some research to make sure the unit you select meets your needs. What may be appropriate for a 30-room property may not be appropriate for a 150-room hotel. The greater the number of rooms, the easier it is to justify an EMS.”
Amana’s PTAC division recently unveiled a new wireless EMS solution for its PTACs. Working with its DigiSmart LED Controller, the system monitors a PTAC’s performance and usage and relays that data via an antennae to a central hub. Once communicated to the Internet, an individual PTAC or group of PTACs can be monitored anywhere in the world. Amana’s Duffey says initial results show a 30 percent energy savings.
One advantage of going with a wall thermostat is that it reduces the amount of interaction a guest has with the PTAC. With less interaction, the likelihood of something breaking is less.
Glenn Hasek can be reached at firstname.lastname@example.org.