Drury Hotels Use ERVs to Cost Effectively Treat Outdoor Air
Rotary energy recovery wheels make a difference
Drury Southwest is a Missouri-based, family-owned and operated hotel system with more than 130 hotels in 21 states. Founded in 1973, the Drury brands include Drury Inn & Suites®, Drury Inn®, Drury Plaza Hotel®, Drury Suites®, Pear Tree Inn by Drury®, and other brands.
The company’s focus on exceptional customer service, spotless rooms, and best-in-class value earned it a JD Power and Associates ranking of “Highest in Guest Satisfaction” from 2006-2014.
HIGH VENTILATION RATES CONTRIBUTE TO GUEST SATISFACTION
Exceptional IAQ has long been a highlight of the guest experience at any Drury Hotel. Many hotels simply ventilate hallways and rely on bathroom exhaust fans to ventilate rooms by drawing fresh air through undercut doors. In contrast, Drury has delivered fresh outside air directly into each guest room for more than three decades. At the same time, return vents continually extract and exhaust stale air from each room.
The management of Drury Southwest, currently headed by company president Dennis Vollink, believes that entering a room that smells and feels fresh is a key to guest satisfaction and repeat business. “We believe that our strategy of bringing fresh air directly into our customer rooms and ventilating appropriately contributed to our winning of the JD Power and Associates Award for Guest Satisfaction, year over year,” said Vollink. “We feel that mold and humidity control is also an important factor in maintaining our buildings,” added Gregg Mrzlak, the mechanical project manager for new constructions and renovations at Drury Southwest.
MAKING FRESH AIR AFFORDABLE
The challenge of prioritizing IAQ and using high ventilation rates is to cost effectively treat the fresh outdoor air for temperature and humidity. For the past 15 years, Drury Southwest has utilized rotary energy recovery wheels manufactured by Airxchange Inc. in new hotel constructions and HVAC system renovations of older buildings. Using an energy recovery wheel to recycle up to 80 percent of the energy in room exhaust air provides “free” conditioning of the fresh outdoor air.
For hotels located in humid climates, energy recovery wheels can be configured with desiccant that momentarily extracts water molecules from the incoming airstream and deposits them into the exhaust airstream, greatly decreasing the moisture load for building dehumidifiers. “ERVs make it affordable to bring in the ever increasing large amounts of outside air required by both codes (ASHRAE 62.2) and our own in-house standards,” said Mrzlak.
AN ONGOING PARTNERSHIP
A pair of similar projects spanning a decade show how Airxchange wheels can be of particular use in the renovation of HVAC systems within the older buildings that are frequently refurbished and converted to Drury hotels.
San Antonio - 2006
Airxchange was used by the Drury design team in 2006 at the Alamo Bank Building in San Antonio, which was converted into a 370-room Drury Plaza Hotel. As part of the HVAC design, Vollink, acting as the principal mechanical engineer in addition to his role as company president, specified Airxchange cassettes. Long an advocate of using ERV technology to enable high ventilation rates, he was also faced with installation challenges and access limitations for the 100-year-old building.
The HVAC system would be located in a small attic and needed to be brought into the space through normal doorways and stairwells. With flexibility in mind, Vollink selected an Airxchange “split-wheel,” also known as the Field Assembled Cassette, that could be assembled on-site. The energy recovery surface is a durable polymer material that has been shown to last as long as 30 years in comfort HVAC applications. The polymer is formed into a matrix and segmented for easy removal or installation from the rigid stainless steel frame, making Airxchange wheels both light and serviceable. “Without Airxchange’s split-wheel design, we would have had a very difficult time finding a way to install the ERV system,” said Mrzlak. “Drury uses ERVs in every project, whether it is a new build or a historic renovation. The historic renovations are usually quite challenging as we have had to design and specify units that have to be brought into the building in pieces, with the largest piece small enough to fit into an elevator and then assembled in place.”
The Drury team’s innovation at the Alamo Bank conversion did not stop with use of the split-wheel design. Drury decided to implement a unique strategy for providing heat, deciding to implement a central electric heater downstream from the Airxchange wheel. The effective pre-conditioning by the wheel minimized the required heating load enough that only supplemental heating was required. This design proved to have a lower first cost and Drury Hotels found it to be an efficient and practical solution.
Cleveland – 2015
A similar theme is evident in one of Drury’s latest renovation projects, the 2015 transformation of the historic Board of Education building into a 180-room Drury Plaza Hotel. Working in tandem with the Cleveland Landmarks Commission to preserve the ornate appearance of the East Sixth Street building, Drury initiated a complete internal renovation, including the installation of a new HVAC system.
Air handling units were purchased from an original equipment manufacturer (OEM) that met the company’s exact specifications, with one exception: Drury specifically requested that the energy recovery wheels that are normally included with those units be replaced with Airxchange wheels, which Mrzlak describes as “cost effective and easy to maintain. We really like the easy way the pie pieces can be removed and cleaned.”
With a wide range of sizes available and decades of experience working with OEMs, an exact match for replacing the original wheels was easily specified.
“This is another tricky project in which the equipment is located in an existing attic with limited access,” said Mrzlak. “All equipment must be disassembled at the jobsite, moved up into the attic through an opening no larger than 60x48, and then reassembled all under the supervision of the factory or a factory authorized service representative.”
The Drury Plaza on East Sixth Street will be completed in 2016. To see the design impact of the Airxchange wheels being used in the Cleveland project, see Figure 1 above.
For more information, visit www.airxchange.com.
Publication date: 4/4/2016