A new school of systems controls

Engineered Systems, June, 2002 by Joanna R. Turpin

All these possibilities are 5 to 10 years off, notes Burhenn, but the main goal of the study was to include the utility infrastructure analysis in CUA's 10-year master plan, which was presented to the District of Columbia.

SAVE THE WATER

Phase 4 began during summer 2000 and involved some of the items uncovered during the Phase 3 analysis, including water conservation, steam trap replacement, some mechanical upgrades to buildings, and a new EMS.

The water efficiency work basically involved the bathrooms, as they are the primary source of water use in buildings. "When you have old buildings like Catholic does, you'll have old plumbing fixtures like toilets and urinals that use a lot of water. New equipment is available that consumes significantly less water per flush, so it's straight math," says Ewart.

CUA has fairly high water and sewer rates, so it was deemed necessary to replace toilets, rebuild urinal flush valves, replace aerators on sinks, and replace shower heads. An added benefit, notes Ewart, is that the university's students are particularly sensitive to environmental issues such as water conservation. In a sense, it's a good marketing tool for CUA to show that it's interested in conserving resources.

A complete steam trap replacement was next on the list. "Most data from manufacturers suggest that traps typically fail after about 7 years in operation," says Ewart. "When a trap fails, it's not possible to recover condensate effectively, so you lose energy efficiency and interrupt the proper flow of steam, which causes heating problems."

Custom Energy used fixed orifice traps, which don't rely on moving mechanical components the way conventional traps do, so they don't require maintenance and they have a longer life cycle. Due to the tremendous job of the subcontractor, notes Ewart, the steam trap replacement project went very smoothly.

The mechanical system enhancements of Phase 4 largely involved three buildings. In one building, electric reheat coils were replaced with hot water coils on several air handlers and vfd's were placed on secondary loop pumps.

In the second building -- Ward Hall, the music building -- the steam heating system was replaced with a new heat exchanger and hot water baseboard heaters. Even though this improved comfort, it technically was not an energy improvement. The system was changed because the steam radiators would ping and bang, often during a student's graduate recital. That was very distracting to the students and resulted in a lot of complaints.

The third building, which contained laboratories and classrooms, had a very large built-up air handler -- two supply fans, two outside air makeup fans, two return fans, all of which ranged between 40 and 75 hp -- with inlet vanes that were pneumatically controlled. The pneumatic controls had failed, so these needed to be repaired or replaced, and vfd's were installed.

THE EMS EMERGES

The EMS is really the piece de resistance of the project. Ewart notes that how the EMS was installed depended on the energy savings that were available at that particular building. "In a few buildings we did complete energy management, where we were doing temperature control as well as starting and stopping major equipment. In a number of the buildings we're doing some basic monitoring and just starting and stopping the equipment," says Ewart.