Energy-Recovery Units Reduce Costs, Avoid Air-Quality Problems

On the campus of Rockingham Junior High School in Rockingham, N.C., where hot and humid weather is common during spring, summer, and fall, buildings are heated and air-conditioned with unit ventilators and fan-coil units connected to a two-pipe hot-water or chilled-water system. During cooling season, chilled water is produced by an air-cooled chiller; during heating season, hot water is produced by a gas-fired boiler. All ventilation is provided through the unit ventilators, which are connected to the outdoors.

For a three-story classroom addition, Richmond County Schools wanted an HVAC system that complemented and supported the existing HVAC equipment and avoided the severe mold and mildew problems newly constructed schools in the area were experiencing because their mechanical ventilation systems did not treat outdoor air independently.

The district installed two Greenheck ERCH energy-recovery units—one 7,500 cfm, the other 7,900 cfm.

With the ERCH units, chiller capacity was reduced by 36 tons, while boiler capacity was reduced by 129 Mbh. Additionally, a unit ventilator serving a typical classroom was downsized to 1,000 cfm of supply air; a classroom unit ventilator conditioning outdoor air directly would have had to been sized at 1,500 cfm. What's more, the cooling-load requirement of a typical classroom was reduced by more than 1.5 tons. Additional cost savings were achieved through the installation of a smaller hydronic piping system, which was made possible by the energy recovery units' reduction of system gallons per minute by an estimated 25 percent.

After one year of operation, the school's principal said he was very pleased with the indoor-air quality provided by the HVAC system.
Greenheck Fan Corp.
P.O. Box 410
Schofield, WI 54476-0410
715-359-6171
www.greenheck.com

Duct Liner Provides Insulation, IAQ Protection, Noise Attenuation

The architects and engineers for the new Rosa Parks Elementary School in Mankato, Minn., hoped to achieve a return on the school district's $21 million investment by minimizing operating costs and designing a school that is long-lasting. Part of that strategy included the selection of AP Coilflex Acoustic Duct Liner, a fiber-free alternative to other duct liners.

Mike Dolejs, owner of Dolejs Associates Inc., the mechanical engineering firm, liked the fact he could insulate duct from the inside, which is better for sound attenuation. With a noise-reduction coefficient of 0.60 and a sound-transmission value of Class 25 when applied to sheet metal, AP Coilflex exceeds ASTM C1071, Standard Specification for Fibrous Glass Duct Lining Insulation (Thermal and Sound Absorbing Material), in terms of sound performance.

Coilflex's smooth, cleanable surface maintains its integrity despite the air velocities within a duct. Additionally, it is made with Environmental Protection Agency-registered Microban antimicrobial treatment, which provides a higher level of protection against mold.

Dolejs expects the Coilflex duct liner to last a long time. This is a great benefit to schools that often wait many years for bond approval to pave the way for much-needed repairs. Unfortunately, not all school districts take the life-cycle cost of insulation into account.

"What school districts have to realize is that HVAC insulation represents only about one-half of 1 percent of the total construction cost of a new school," Kartik Patel, global HVAC market manager for Armacell, said. "These costs pale in comparison to a costly mold remediation."
Armacell LLC
7600 Oakwood Street Ext.
Mebane, NC 27302
919-304-3846
www.armacell.us