Designed by architect I. M. Pei in the 1960s as part of Cleveland's urban renewal project, the Anthony J. Celebrezze Federal building retains the broad-shouldered, confident visage typical of the glass-and-steel office buildings of the era. After 35 years, though, the inside of the 32-story building was beginning to show its age.

The HVAC system was not only inefficient, but uncomfortable. Tenants complained that the fan coil units, located in offices around the perimeter of the building, were disruptive and provided ineffectual heating and cooling.

Following a building-wide assessment, engineers at Westlake Reed and Leskosky, Cleveland, designed a mechanical upgrade to reduce energy costs and improve tenant comfort. This included replacing the existing 4,640 fan coil units with new, custom-designed models from Daikin.

The project became a study in organization and efficiency—so efficient, in fact, that it was completed two months ahead of schedule and $4.5 million under budget.

A major requirement of the renovation dictated the course of the project: the building was to remain fully occupied and functional during the upgrade. To accomplish this, contractor teams went to work after the building's employees went home for the day—replacing fan coil units four nights a week, every week, for almost a year. When employees arrived at their offices the next morning, the only evidence of the overnight overhaul were the new fan coil units—custom designed by Daikin to minimize installation time.

Assembly-line efficiency was a key to the project's success, according to Jeff Klie, the mechanical contractor who managed the project for the Smith & Oby Company. "You've heard of the perfect storm? The Celebrezze project could have been one, but it became the perfect project instead." Also important was close project coordination between the General Services Administration (GSA), Smith & Oby, and Daikin. "When you are able to get done two months ahead of schedule and $4.5 million under budget," noted Klie, "it speaks to the team effort."

Renewing an "urban renewal" building

About 5,500 federal employees work in the structure, including staffs of the Defense Finance and Accounting Service, Internal Revenue Service, Small Business Administration, Equal Opportunity Employment Commission, the Coast Guard, and the departments of Veterans Affairs and Housing and Urban Development.

On each floor, four-pipe fan coil units supply zoned heating and cooling to offices on the perimeter of the building. The four-pipe system (hot and cold water supply and return) allows some units to be in heating mode and others in cooling at the same time. It also allows for reheating of cold dehumidified air before it enters the work place. Depending on room size, each office has 4, 6 or 8 fan coil units. Air handling units located in the basement circulate conditioned air to central spaces throughout the building. Chilled water for the system comes from an off-site, central chilling system operated by Cleveland Thermal Energy.

A major component of the building renovation was replacing the original 37-year-old fan coil units, which had outlived their usefulness in terms of comfort, efficiency and maintenance. The only temperature control for the units was changing fan speeds (low, medium or high) so employees were often either uncomfortably cold or hot. Drain pans on some units collected moisture, so indoor air quality was a concern. In addition, the need for constant maintenance and repair was disruptive for tenants and a financial burden for building management.

To alleviate these problems, Daikin designed the new fan coil units to accommodate a wide range of temperature preferences. Modulating valve control is included to provide more even heat distribution and less fluctuation in temperatures by controlling both the temperature of the air delivered and the fan speed. A high-efficiency centrifugal fan assembly helps minimize noise and vibration for increased occupant comfort.