UConn Office of Environmental Policy

Promoting sustainability at UConn


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Retro-commissioning at UConn

by Alexander Samalot, OEP Intern

The variable frequency drive

UConn is currently undergoing a significant conservation and construction effort that many students may not know about. Currently buildings are becoming drastically more efficient through adjustments in the way energy is handled. I recently sat in on Sebesta’s (an engineering and design service company hired by the school) meeting. They were explaining to the UConn Utility services the changes that have been made across campus followed by a tour of the newest completed building, the Agricultural Biotechnology Laboratory.

What Sebesta has done is a process called retro-commissioning. It involves specifying building occupancy schedules, allowing for certain utilities to be turned down or off when not needed. Previously buildings would run the CO2 and heating/cooling ventilation based on the hours that the building had expected use. This wastes a tremendous amount of energy for unused space. Even small changes in the run time and rate of heaters and chillers and ventilation can have exponential savings.

The pumps controlled by the variable frequency drive

Most of the explanation regarded the changes in the newest retro commissioned building, the agriculture biotech facility. Due to these changes there is supposed to be an annual savings of $112,000. The large number of laboratories in the building needs a significant amount of ventilation for the potentially dangerous chemicals. The laboratory I toured was a Biosafety level two (out of four). It is not a life threatening area; biosafety level two simply means certain biological agents may be used in the lab, which demonstrates the need for lab ventilation.

There are three places which were specifically retro-fitted; one is the lab itself, the fume hood and the biosafety cabinet.  There are new controls using top of the line technology such as infrared and camera controlled zone pressure sensors. This is a very technical way of describing a box which detects if someone is sitting in front of the hood, which automatically turns off the ventilation when not in use. Also there are new valves called VAV’s which open and close using a mechanical arm when not in use and operate at a highly reduced flow. The building itself offers Variable Frequency Drives which are newer computers controlling water and air pump motors that move all of the warm and cool air and water throughout the building. These controllers drastically decrease the energy costs of the building causing very large savings and reduced energy use.

The Retro commissioning project is a great example of how new technology can be successfully implemented to have a large effect on campus. The existing buildings have had their existing infrastructure optimized resulting in notable reductions in energy use and savings for the school. With the construction of so many new buildings on campus focused on sustainability , it’s important to remember that there are buildings on campus that are over sixty years old that have significant room for improvement.