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WaterFurnace located the units and designed the air-duct systems by dividing the building into zones, grouping similar usage areas together. For example, one unit handles several offices facing the same direction and having similar heating and cooling needs. Breaking the building into zones with similar requirements provides better comfort than large central systems where all areas are governed by one thermostat.
Horizontal units were used throughout the facility to maximize usable floor space. The units are located above the suspended ceiling in an otherwise unused space, which also serves as the return air plenum. This also eliminates the need for expensive return air ductwork. A percentage of fresh, outside air is directly ducted to each unit to provide a healthy indoor environment. A heat recovery system was installed to recover the energy from exhaust air such as in restrooms. This energy is used to condition the incoming fresh air, providing for high-energy efficiency.
One of the many benefits of a geothermal system is the significantly reduced space requirement for the mechanical room. The WaterFurnace mechanical room is less than one-sixth the size that would have been required with a conventional system. This feature allows more floor space to be devoted to income-generating operations.
To maximize the pond view, a ribbon of glass surrounds the perimeter of the building throughout the office and manufacturing areas. When faced with large amounts of glazed areas, many engineers install perimeter radiation for heating, which is expensive to install and operate. With geothermal units, the supply-air temperatures are high enough that ceiling-mounted linear-slot air diffusers can be used to blanket the perimeter wall with warm air for high comfort at low installation and operation costs. The main lobby, designed with two-story glass walls, presented a challenge for lower-level comfort. For this unique situation, a Premier AT down-flow unit was installed to condition this space. The ductwork was located within the floor slab so the supply air could be introduced at floor level, where the occupants are.
The 24-foot-high manufacturing area uses a stratified air concept to minimize cooling loads. In summer, the units are ducted to condition only the lower ten feet of the space. This allows the massive amounts of heat gain from the roof and overhead lighting to remain near the ceiling, where it does not require conditioning. During the winter, this upper-level air is used to assist in heating. By using a stratified air system, only 70 tons of cooling is required in the 85,000 square-foot area. With a conventional rooftop system, a space this size would typically require 200 tons of cooling.