By Chika Acholonu | Mar 3, 2015

This post was originally published in the UW Green Labs newsletter. Each quarter, the newsletter covers a topic on how labs can improve their scores in one category covered by the UW Green Laboratory Certification Application.

Click here to read the rest of this quarter's newsletter and subscribe to future UW Green Labs mailings.


Reducing your lab's energy use

With regular maintenance, you can significantly increase the efficiency and the lifespan of your lab’s freezer or fridge. In fact, regular maintenance of your ultra-low temperature (ULT) freezer can save your lab up to $280 per year in energy costs.

One important part of freezer and fridge maintenance is cleaning the condenser coils and filters. Over time, these accumulate dust and dirt, which reduce both air flow through the filters and the coils’ ability to transfer heat out of the appliance. Filters should be checked at least monthly, while condenser coils should be cleaned at least yearly[i]. For information on how to clean your freezer or fridge coils, visit:

Besides cleaning your freezer’s coils and filters, it is important to regularly defrost your freezer. Frost buildup inside a freezer causes gaps in seals, allowing warm air to enter the freezer[ii].

To defrost your lab’s freezer:

  1. Remove all samples from freezer and move them to another location temporarily
  2. Turn off and unplug freezer
  3. Allow defrosting for 24-48 hours; towels may be placed in or around freezer to prevent water leaks
  4. Clean and dry inside of freezer
  5. Turn freezer back on
  6. Allow freezer to cool to proper temperature before putting samples back into freezer

If your lab would like a freezer cleaning kit (freezer gloves and ice scrapers) to make this task easier, a kit can be requested using this form.

Shut the Sash

The average fume hood uses more energy than the average home. To conserve energy and ensure your lab’s safety, it’s vital to close your fume hood’s sash when the hood is not in use. When the hood is in use, the sash should be kept as low as possible.

Two general types of fume hoods are used at UW: variable air volume (VAV) and constant air volume (CAV). In a VAV fume hood, air volume and fan speed change with sash height. In a CAV fume hood, air volume and fan speed stay constant no matter the sash height. Thus, a VAV is typically more energy-efficient than a CAV. All fume hoods at UW-Seattle are labeled with a small green sticker from EH&S right above or to the side of the sash. This sticker tells you what kind of fume hood your lab has.

Why Turn Up the Temperature on Your ULT Freezer?

Studies by UC Davis and the University of Colorado suggest that turning up your ULT freezers from -80 to -70°C is not detrimental to biological samples. In addition, doing so can extend your freezer’s lifespan and help your lab conserve energy. Check out these universities’ joint database of samples stored at -70°C or higher here for more information.

[i] U.S. Dept. of Energy. Office of Energy Efficiency & Renewable Energy. "Everything You Wanted to Know about Running an Ultra Low Temperature Freezer Efficiently but Were Afraid to Ask…", accessed 6 Feb 2015.
[ii] Ibid.