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¶¶Òõ̽̽ has both a large central high pressure steam plant with 5 boilers and multiple other building/boiler combinations of high/low pressure steam and hot water boilers throughout the campus. This project was implemented on the Central Utility Plant (CUP) high pressure steam boilers which have a fully metered and cross limited control configuration. Three of the 5 boilers have forced draft fans equipped with variable frequency drives (VFD) for modulating the air flow volume with the boiler load; the other 2 boilers did not have VFDs. The installed VFDs were not operating in the PLC logic – they were functioning in an on/off manner with air flow changes being accomplished with modulation of the fan outlet dampers. 

The new updated configuration included fan and other programming changes. The 3 units with VFDs had new air/fuel curves developed (reprogrammed) to have the VFDs modulate with the fuel and boiler load. The other 2 units had VFD’s installed, and one required an inverter rated motor installed. Additionally, these other units had their respective air/fuel curves developed (reprogrammed). The outlet damper control was also reprogrammed to operate in conjunction with the VFD for that segment of the oxygen trim control loops and the fuel valves were removed from this logic. The removal of the fuel valve from the oxygen trim control loop eliminated hunting in the control operation and contributed to the fuel savings for this project. 

Staff from the Central Plant Operations team, the Controls team and the Utility Engineering team contributed heavily to the success of this project. 

Project Cost: $146,000
Utility Company Rebates: $102,000

Annual Savings:
Estimated Fuel Cost Savings: $179,800/year
Total CO2 reductions: 2,436,000 lbs/year

¶¶Òõ̽̽’s Stafford Hall houses important research for the Department of Microbiology and Molecular Genetics and the Department of Orthopedics and Rehabilitation along with additional classroom and laboratory space. With such demanding space usage, it is critical to ensure the HVAC systems provide year-round operation. Several decades since Stafford first opened, some of the HVAC equipment needed replacement.

 Stafford Hall is served by four air handling units that condition 100% outside air and deliver it throughout the building. Air conditioning during summer months was provided by direct-expansion (DX) condensing units that were original to the facility, and at 33 years old, this equipment was failing and unable to adequately or reliably provide cooling. The original equipment also used a potent greenhouse-gas and ozone-depleting refrigerant. 

¶¶Òõ̽̽’s Utility Engineering group with support from the Medplex Maintenance Zone identified a smarter, more efficient solution to these problems and planned an extension of the central chilled water system which is fed from the Main Campus District Energy Plant. This effort began with the foresight to extend larger pipes through the new Firestone Medical Research Building during its construction, and then route the piping through the Health Science Research Facility (HSRF), and through the sky-bridge that links HSRF to Stafford Hall. The new pipes were then connected to new chilled water coils to replace the DX (direct expansion) refrigerant coils inside each of the four air handlers.

¶¶Òõ̽̽ operates its primary data center at a leased site in Technology Park in South Burlington. Continuous cooling for the space is vital for safeguarding the computers and servers which support critical research, learning and information storage. 

At the onset, ¶¶Òõ̽̽ purchased electricity from the local utility and chilled water from the building owner, and maintained a generator and chiller located on the roof as backups in the event of a utility failure.  When the existing backup chiller had reached the end of its service life, ¶¶Òõ̽̽ planned for its replacement and engaged in a study to improve energy efficiency and identify other potential energy savings for operating the data center.

The project entailed decommissioning the existing air cooled chiller and designing and installing a newer, more-efficient system

For over a decade, as deferred maintenance funding is available, repairs and improvements are made to reduce thermal energy loss throughout the campus steam distribution system. Removable insulation is custom fitted on all steam system piping and valve covers. 

¶¶Òõ̽̽’s Fleming Museum is one of the oldest museums in the state and an architectural gem on its own. The most recent major upgrades were completed in 1984 and included an HVAC upgrade that provided critical environmental controls for the collections housed and loaned to the Fleming Museum. The museum had its air conditioning served primarily through a 50-ton air-cooled chiller, whose reliability and frequent service needs left no choice in the summer of 2022 but to bring in a temporary, rental chiller. The equipment’s lack of reliability and discovery that the chilled water piping was failing created a need for a planned project to replace this aging equipment.

A new chiller was selected, but there were almost no reasonable options for locating the equipment near the building without impacting both aesthetics and historical preservation. There was one location where a separate DX (direct expansion) air conditioning unit sat that could house the chiller, this equipment provided air conditioning to the 1984 storefront. Thanks in part to a simultaneous project to renovate the 1984 storefront addition, the Utilities Engineering team and their consultants determined that the cooling loads of the storefront could be picked up by this new chiller which was already ordered due to lead-time constraints. This meant that two pieces of equipment would be consolidated to one, reducing service cost and increasing reliability, while also reducing the use of the fully phased out, ozone-depleting and potent greenhouse gas refrigerant (R-22) used in the two old pieces of equipment.

Construction began on the chiller replacement project in October of 2024 and was completed in May of 2025. The project included the replacement of rotting carbon-steel piping with new stainless-steel piping, new pumps with variable frequency drives, a new chilled water coil for the storefront air handling unit and upgraded controls. This upgrade is estimated to save the university more than $5,500 per year with a 15-year payback of over $90,000 including $10,400 in utility incentives. The energy savings alone are compelling, but perhaps the best value is the increased reliability of the new equipment. The service headaches of mobilizing a rental chiller and the avoided aesthetic impact of rental equipment is a major improvement that will pay dividends for years to come.