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Southwest HVAC News
Texas Christian
University's Arena Renovation Challenges HVAC Engineers and
Contractors.
Engineers overcome venue's HVAC equipment space limitations and
design/installation challenges of new 47-foot-high,
60-inch-diameter duct.
HVAC consulting engineers and contractors were dealt a tough hand
during the renovation of Texas Christian University's (TCU)
basketball arena and they weren't playing Texas Hold 'em Poker.
The conversion of the 55-year-old, 70,000-square-foot Daniel-Meyer
Coliseum into the new Ed and Rae Schollmaier Arena presented many
HVAC engineering challenges for Baird Hampton & Brown (BHB) Inc. The
Fort Worth, Texas-based consulting engineer/architecture firm
spearheaded the HVAC portion of the $72 million renovation, which
included new locker rooms, expanded common areas and 140,000 square
feet of building additions.
Some of BHB design and mechanical contractors' installation
challenges included:
• limited indoor areas available for the new air handlers because
design committee members discouraged roof placement on the
renovation's new one-story build-outs for aesthetic reasons;
• Hanging new spiral metal air distribution duct from a bowl-shaped
roof not originally intended for supporting the estimated 1,500-tons
would require costly roof structural upgrades;
• Installing tons of 60-inch-diameter metal ductwork 47 feet high
would be a jobsite safety concern for HVAC contractors;
• and strict year-round humidity and temperature tolerances were
required to maintain the new wood basketball floor.
Fabric duct, which is 90-percent lighter than metal duct, was BHB's
solution to both the project's roof load-bearing limitations and a
value engineering alternative to metal.
However, the architecture committee was concerned with the deflated
appearance associated with older style fabric duct during idle air
handler periods.
Recent industry developments of in-duct tensioning systems convinced
the committee to use the FTS (Fabric Tensioning System) Jumbo Series
from the SkeleCore product line manufactured by DuctSox Corp.,
Peosta, Iowa. SkeleCore is an in-duct, cylindrical metal framework
tensioning system that's field-adjustable with a wrench for taut,
wrinkle-free and inflated-like aesthetics regardless of air handler
operation. The lightweight internal framework also has a minimal
friction loss of only 0.04-inches w.g./100 feet.
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Improvements in
Air Comfort
The arena's previous HVAC was provided by 26 indoor air handlers
supplied with chilled water from an offsite central plant and
hot water from onsite boilers in a basement pump room. Air
handlers were evenly positioned inside the encircling mezzanine
level corridor outside the seating area. The air handlers'
plenum-supplied wall registers were positioned every 25-feet
around the circular-shaped seating area's back wall. The design
was state-of-the-art in 1961, however drafts near air discharge
diffusers and inadequate return air draw through courtside
grilles 100 feet away sometimes created an uncomfortable air
environment. Thus, purge fire/safety exhaust fans were used to
pull more air through the arena during heavily attended events.
Unlike the original
back wall air distribution positions, BHB's fabric duct ring hangs
approximately 40 feet out from the back wall and disperses air more
evenly throughout the seating and court areas. Air is dispersed
through a linear array of laser vents that throw at three velocities
of 150-fpm at 3 o'clock; 100-fpm at 4-o'clock and 9-o'clock; and
50-fpm at 8-o'clock. "The laser vents are capable of velocities that
reach center court without the need of high-velocity nozzles," said
Josh Schmidt, P.E., mechanical engineer and a member of BHB's design
team that included Principal Ian Bost, P.E., LEED AP; and Ken
Randall, P.E., electrical engineer.
Space Restrictions
for HVAC Units
The renovation included build-out areas for concessions and the
circular corridor's widening. With no ground space available and the
existing build-out structurally incapable of HVAC unit loads, the
new build-out's roofs were the only solution for the placement of
three 50,000-cfm air handlers manufactured by York, York, Pa. While
BHB would have preferred three symmetrical supply points at 3, 7,
and 11 o'clock into the circular fabric supply duct for even airflow
and low velocities, the build-out roofs' unsymmetrical positions
around the arena permitted only air handler supply radius entry
points of 10, 8 and 4-o'clock in the circular duct design Therefore,
airflow is designed to flow right or left, but not both directions,
once entering the fabric duct ring via metal duct tee connections
from the air handlers. DuctSox's manufacturer's representative,
Bartos Industries, Fort Worth, assisted BHB in engineering the
fabric duct's airflow, velocities and the calculations of the
10-degree transitions between every 16-foot/10-inch-long section to
complete a 550-linear-foot circle of 60-inch-diameter duct. All
fabric duct and metal duct connections were installed by McCorvey
Sheet Metal Works, Houston.
The York packaged
systems also include coils for preheating outdoor air, reheating
during the dehumidification cycle, cooling and electric humidifiers
for maintaining strict wintertime relative humidity levels required
by the basketball court flooring manufacturer. The strict
environmental tolerances are monitored and controlled by the
campus-wide Metasys building automation system (BAS) manufactured by
Johnson Controls, Milwaukee, Wis. Other equipment BHB specified were
exhaust fans manufactured by Loren Cook Co., Springfield, Mo., and
specialty area fancoil units manufactured by Enviro-Tec, Largo, Fla.
Other equipment BHB
specified is an additional 6-MBH condensing boiler manufactured by
Aerco International, Blauvelt, N.Y., to accommodate the building's
added space requirements and to supplement three existing 2-MBH
condensing boilers. All pumps were replaced because of age. BHB
incorporated a new hydronic strategy of redundancy with two 50-hp
chilled water pumps and two 25-hp hot water pumps and two 10-hp
general water pumps.
Thanks to an
ample-sized mechanical room and BHB's first use of Autodesk's
Navisworks construction modeling software, the hydronic change outs
were seamless. No downtime was experienced from unexpected
obstructions or hydronic connection incompatibilities by the
project's mechanical contractor, SkiHi Enterprises, Fort Worth.
"One major project challenge was keeping the existing pumps and
boilers on line during the renovation to maintain services to the
arena complex's many connected buildings depending on the original
facilities hydronics," said Schmidt.
The lowering of the
playing court four feet for better stadium seating views, plus
adding locker rooms and other sublevel spaces, also allowed BHB to
design more courtside return air, which feeds an existing concrete
return air shaft. The shaft feeds a plenum above the encircling
concourse that supplies the York units, which mix it with outdoor
air as per data from the arena's CO2 sensors and the BAS.
BHB might have been
dealt a tough hand, but their HVAC retrofit design of a 55-year-old
athletic complex serves as a role model of indoor air comfort and
energy efficiency for future arena renovations around the nation.
About DuctSox:
DuctSox Corp. (www.ductsox.com), is a Peosta, Iowa-based
manufacturer of fabric ductwork/accessories that markets its
products globally through HVAC/R manufacturer's representatives. For
more information visit www.ductsox.com, email sales@ductsox.com or
call 866-DUCTSOX. DuctSox Corp., 9866 Kapp Ct., Peosta, Iowa, 52068.
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