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Sterilizer Retrofit

Responsible Party: RESPC and Energy Management

Project Highlights

  • $77,000 allocation by the Renewable Energy Special Projects Committee in 2014
  • 15 sterilizers retrofitted since 2016
  • 3,000,000 gallons of water saved annually

Project Summary

  • Evaluated potential measures to save water and energy used by sterilizers, including the costs, savings generated, and payback period.
  • Worked with sterilizer users to determine when they should “sleep.”
  • Installed valves that stop steam and make up water from flowing during “sleep.”

Project Description and Approach

Sterilizers are used by researchers and medical professionals to sterilize equipment through the sanitizing power of steam. Traditionally, sterilizers are constantly fed steam to keep them ready for use. As the steam cools it forms a condensate that is too hot to be sent down the drain alone and must be mixed with make up water to cool it down. RESPC funded a project to pay for energy and water saving retrofits to existing sterilizers. The retrofit allows sterilizers to be put to sleep on a programmable schedule – both steam valves and make up water valves are closed. This stops the use of potable water during that time. This project typically puts the sterilizers to sleep for about eight hours each day and is already saving millions of gallons of water annually in just the two buildings in which they have been implemented.

Retrofitting existing equipment is often more cost effective than purchasing new sterilizers. The current strategy was chosen for it’s short payback period, which was estimated at less than two years in the initial audits for all of the buildings chosen. So far, the project has been largely under budget.

As of Fall 2018, five sterilizers at the Lineberger Cancer Research Center and 10 in the Genetic Medicine Research building have been retrofitted with valves and software programming that puts the machines to “sleep” during hours of inactivity. They are referred to as asleep instead of turned off because they can be easily brought back online with only a brief warm up time. Project Manager, Obadele St. George, talked with researchers on each floor of the buildings to figure out what times for sleep worked best for their schedules.

In 2019, the Medical Biomolecular Research Building was retrofitted, bringing another 14 sterilizers on board. St. George hopes they will continue to grow the program.

“I thoroughly enjoyed this one,” said St. George. “I liked working with occupants on equipment to do their work better and to do better for the campus and to help make UNC more green and reach the goals of net zero water use and greenhouse gas emissions.”