The majority of the building is served by a central variable-air-volume air-handling system incorporated into a custom mechanical penthouse that conditions 100% of outside air. An independent air-handling unit serves the basement vivarium, while another unit re-circulates air for the atrium and provides ventilation. All three units are equipped with airside economizers, which use outside air to cool indoor spaces when exterior temperatures are favorable.
The heating system consists of a perimeter radiant heating loop that runs through ceiling cavities and re-heats variable-air-volume boxes dispersed throughout the ductwork—all of which rely upon high-temperature hot water supplied by the campus' central plant.
The temperatures are reduced to 180 degrees through three heat exchangers in the basement. Two generate hot water used for heating and domestic hot water, and one generates steam for the building's humidification and laboratory sterilization. Two radiantly heated slabs provide comfort heating at the atrium doors and melt snow on the plaza outside.
The air-handling units feature three-stage cooling, with two stages of evaporative cooling and a third stage of traditional mechanical cooling that utilizes chilled water from the campus' central chilled-water plant.
Ventilation in the laboratories was a key factor in the building's overall energy performance, says project manager Ryan Ockey with Salt Lake City-based Van Boerum & Frank Associates Inc., mechanical engineers for the project.
"Laboratory spaces are known energy hogs," Ockey says. "A substantial amount of air is needed to dilute fumes from the hazardous chemicals used in the labs, and conditioning air can add thousands of dollars per hood to the building's energy bill in a year."
To reduce air requirements and energy consumption, the laboratory bays will utilize variable-air-flow fume hoods equipped with automated sashes and proximity sensors that reduce airflow rates when not in use.
Ventilation in the laboratories requires exchanging a large volume of outdoor air, which must be heated or cooled to maintain comfortable indoor temperatures. To minimize energy required to pre-treat incoming air, the heat-recovery system captures and reuses heat and cooling energy from the fume-exhaust hoods.
A run-around loop feeds the building's central air-handling unit and the vivarium unit. The loop is made up of six coils and six pumps, which circulate a glycol-based antifreeze that transfers heating and cooling energy from the fume exhaust back to the air-intake system. This lowers the temperature of incoming air in warmer months and preheats incoming air when it's cold outside.