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Building Manager Green Tip

February 2011

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Green Your Ultra Low Temperature Freezers


While the hundreds of Ultra Low Temperature (ULT) freezers on campus may only take up a few square feet per lab, most are major consumers of electricity which means they have a significant impact on Harvard’s goal to reduce greenhouse gas emissions. For example, the majority of freezers in FAS labs consume about 18-20 kWh/day resulting in a utility cost of roughly $1,000 per year per freezer at current rates. This month we provide tips for how you can reduce energy and save on utility costs by exploring energy efficient freezers and adopting more efficient operational practices.

Efficient Freezer Selection Considerations


  • Many efficient freezers feature vacuum insulation panels to allow efficient storage while maintaining a small physical footprint.
  • Freezers emit a lot of heat into their surrounding environment. When possible, try to locate freezers near fume hoods or other ‘free’ cooling sources instead of spaces with low ventilation requirements. Similarly, do not locate freezers close to other sources of heat if possible.
  • Many manufacturers now provide energy consumption statistics in kWh/day. It’s suggested that you convert these ratings to include kWh/day/liter of capacity as freezer sizes are not standardized. Efficient models generally run between .017-.021 kWh/day/liter.

Operational Efficiency Tips


Building managers are encouraged to discuss operational changes with researchers in their buildings to ensure that all savings opportunities are realized.

  • Defrost the freezer coils at least once per year, or when ice buildup reaches more than 2 cm thickness.
  • Ensure that air filters are regularly cleaned/replaced and that condenser coils are dust-free.
  • Check door seals to ensure no air is escaping.
  • A full freezer will require less cooling to maintain its temperature than an empty freezer.

Freezer Management Programs At Harvard

The FAS Green Program is embarking on a Freezer Management Program designed to help building managers and researchers better understand the consumption patterns of existing ULT freezers on campus. The first phase will sub-meter and track the performance of a representative sample of freezers for a month to determine how current operating and maintenance procedures impact utility usage rates. Based on the results of this pilot study, the FAS Green Program will work with building and lab managers to develop best practices and policies to reduce the impact this equipment has on the FAS greenhouse gas reduction targets.

The Harvard School of Public Health (HSPH) has a Freezer Taskforce which is collaborating with the Medical Academic and Scientific Community Organization (MASCO). They are currently investigating the possibility of developing a comprehensive freezer inventory system and a friendly competition based on reducing sample storage.

Green Building Services provides consulting services to ensure that the design, construction and operation of Harvard's built environment has minimal environmental and human health impacts, maximizes occupant comfort and generates an awareness of sustainable design and building operations. To learn more about our work and services, visit http://green.harvard.edu/gbs.