Engineered Systems Magazine - March 2008To handle increasing enrollment,
Lincoln-Way Community High School District, just 40 miles southwest of
Chicago, approved the construction of two new 2,500-student high
schools. The 414,000-sq-ft Lincoln-Way North High School, situated on a
98-acre site, will be the first to open to freshman, sophomores, and
juniors in the fall of 2008.
The plans include construction of
70 classrooms, 17 labs, an auditorium, a field house, a
professional-size football field, competition gym, Olympic swimming
pool with moveable partition, library and information center, a
three-bay shop that will provide automotive service to the public, and
daycare for student parents.
All About The Finish
To meet their rigid schedule, Henry Brothers Construction Company
(Hickory Hills, IL) needed a temporary air management solution that
would allow them to apply finishes without having to fire up the
permanent HVAC system. In order to place tile flooring, the concrete
had to have moisture content below 5 lb of water per 1,000 sq ft. Based
on a referral, they called Steve Lupella and Valerie Taylor of
TEMP-AIR, a provider of temporary, portable heating, cooling,
dehumidifying, and air filtration services.
According to the
Sheet Metal and Air Conditioning Contractors’ National Association
(SMACNA), use of the permanent HVAC system in an attempt to dry wet
surfaces, such as drying recently poured concrete floors or expediting
the installation of carpet or wooden floors should not be permitted.
Permanent HVAC systems typically are not designed or constructed to
perform in such a manner. Such activities may result in subsequent IAQ
problems associated with mold and other related airborne contaminants.
Construction
heaters are generally not intended to heat the space for worker
comfort. The first priority is to control the moisture resulting from
construction processes such as concrete curing and fireproofing. Drying
will require that the moisture be exhausted, either by infiltration or
mechanical ventilation. That’s why, when opening this project for bid,
Henry Bros. specifically requested makeup air heaters.
Makeup
air is air from the outdoors that is heated and then evenly distributed
indoors in a controlled manner to replace the air that is being
exhausted. This drier, tempered fresh air has the ability to absorb
moisture, and ventilate the toxic fumes from the construction process.
It provides lower relative humidity levels and dewpoint temperatures
inside the building to prevent condensation and minimize the potential
for mold.
TEMP-AIR designed the IAQ proposal for this project
for outdoor conditions of 10˚F with a desired inside temperature of
55˚. The school’s walls and roof were complete and insulated, but
TEMP-AIR also recommended that the empty windows and doors be covered
with a material suitable to retain heat.
TEMP-AIR calculated
fuel consumption for the six months of heating using project specific
information and regional temperature data from the National
Oceanographic and Atmospheric Administration (www.noaa.gov). Using that
data, the estimated heating load for the entire space amounted to
11,895,001 Btuh based on maintaining at least 55_ inside temperature
and providing a mechanical ach of 0.47.
In November 2007, TEMP-AIR delivered and installed a mixture of equipment from its THP Series makeup air heaters:
- Seven THP-750, rated at 4,000 cfm of air with a variable gas-fired burner
- Six THP-1100, rated at 6,000 cfm of air with a variable gas-fired burner
- One THP-2000, rated at 11,000 cfm of air with a variable gas-fired burner
Dropping The Pounds
“The units were all – located – at the exterior of the building,
which allowed us to install the floor finishes on the interior of
vestibules and doorways without removing or relocating the units,” said
John Tondelli, project manager for Henry Bros.
According to
Tondelli, prior to installation of the portable heating equipment,
initial readings of the space were between 6 to7 lb of moisture/1,000
sq ft, well above their 5 lb requirement. Within a few weeks of running
the TEMP-AIR equipment, readings dropped down to between 3 and 4 lbs,
with temperatures averaging 60°.
“By utilizing makeup air
heating units, the humidity levels helped establish permanent
conditions for various finishes to be installed, such as – cabinetry,
painting, vinyl composition tile, and wood flooring.” The units
performed well enough that the same process will be repeated for
Lincoln-Way West High School, opening the fall of 2009.
ESTo read the entire case study in the March 2008 issue of Engineered Systems magazine - click here.
