The new slab/concrete tilt-up style chapel for the Calvary Chapel Bible College uses seven 74-foot-long runs of fabric ductwork.

Consulting engineer, Thomas Krusic, P.E., principal, Krusic & Associates, and architect, Richard Dayton, principal at Dayton Associates--Architects chose fabric duct because of its superior air dispersion. The fabric duct, manufactured by DuctSox, Dubuque, Iowa, uses linear diffusers that supply even and gentle cooling/heating air dispersion along the entire length of the duct.

This close collaboration between engineer and architect not only saved HVAC installation time and labor, but also more than $100,000 in building structure costs. By utilizing the lower and stronger roof of the accompanying building area to support the rooftop units, Dayton was able to incorporate a lighter and less expensive roof design for the chapel. Subsequently, the lighter roof design resulted in a more aesthetic looking chapel inside because it didn’t require obstructive column supports.

For mechanical contractor, Air Control Systems, Placentia, Calif., the connection of the DuctSox to units was simple as a result of Krusic’s design.

Krusic did get assistance on designing the DuctSox diffuser size and placement as well as pressure loss considerations. Salesman, Victor Petring of manufacturer’s representative, Toro Aire, and DuctSox’s factory engineers’ calculations recommended that each duct run have two of DuctSox’s Sonic Vent linear diffuser systems factory installed. “One of the things that lead us to DuctSox is the fact it could be put up in the truss space while still providing good air distribution,” added Krusic.

Since the multi-purpose room will also be used for sports activities, another fabric duct feature Krusic found attractive is durability. Instead of being dented or damaged by errant sports balls, fabric duct bounces back to its original shape. “One thing Rick (Dayton) and I knew from past experiences is that combining kids and basketballs can result in damage when the ductwork is metal,” noted Krusic, who had teamed with Dayton on many previous projects.

Krusic also found fabric duct to be more sound attenuating - important for chapel activities. Fabric duct’s softness actually absorbs sound. “It appeared to me that the sound attenuating characteristics of fabric duct were more appropriate when the room functioned as a chapel,” Krusic noted.

“I think a hidden benefit fabric duct has is the fact some of the air blows through the material and lessens accumulations of dust on the duct,” added Dayton. “Although this was our first use of fabric duct, I can see its additional benefits in open architecture buildings such as adding color, plus it has a cleaner, more streamlined appearance.”