Our work at this high-rise building started because of a severe building pressure problem during the economizer mode. We discovered the large fan systems were moving excessive amounts of air, thus contributing to the relief problem. During the first few years, AHU modifications were phased, with the major modification being to reduce supply fan speed and re-balance the areas served by these units.

The following is a list of subsequent projects we developed over a total of 10 years:
• Control upgrade for fan systems
• Control upgrade for chiller plant
• Control upgrade and mechanical improvements to provide more consistent condenser water for tenant computer room cooling units
• New more efficient burners were installed on the old steam boilers, and controls were added to this boiler plant to automate it and connect it to the existing BAS.

We have also installed VFDs on all five large constant volume fan systems. This allows the fans to slow down during lightly occupied hours, thus saving fan energy. The BAS is also programmed to slow the fan speed when the return air relative humidity gets above a set point during the summer cooling mode. This reduction in airflow will cause the system to provide colder discharge air which will provide better dehumidification.

We added isolation control valves to the perimeter two-pipe fan coil risers to shut off heating water to different building exposures when the outdoor solar conditions cause those exposures to be sufficiently warm.