Why do we Defrost Freezers if Ice is Insulating?

Last week we challenged the Freezer Challenge community to explain why freezers need to be defrosted if ice is insulating.  A huge thanks to all who took the time to reply.  You've all received bonus points on the Challenge!

Today we're featuring two great responses.  Jerry Stewart, lab manager of the Beierle lab at the University of Alabama, Birmingham wrote, "While yes, ice insulates...[t]he ice has a reverse effect in a freezer. Ice insulates around the coils, which must get colder than 0C in order to maintain a temperature below the freezing point of ice. This ice prevents [the] exchange of heat in the freezer with the coils. The compressor has to work harder ... to overcome the ice insulation around the coils... Temperature exchange in the freezer environment is achieved much more efficiently with little, to no ice buildup..."  

Samantha Clements from the Smith lab at the Scripps Institution of Oceanography at the University of California, San Diego added, "Ice buildup on freezers can inhibit even air flow throughout the freezer, creating an environment with both hot and cold spots which can affect freezer efficiency and also sample integrity. Removing ice ensures continued air flow and even cooling throughout the freezer. "

We could not have said it better ourselves!  We'd also like to recognize the University of Alabama, Birmingham and the University of California, San Diego's Green Labs Programs, as both of our featured responses came from labs that are Green Lab Certified.

Thanks again to Jerry and Samantha for sharing this information!  And remember - even if you didn't receive bonus points for answering the question, you're sure to receive Freezer Challenge points for defrosting your freezers.

The Case for Removing Ice 

We are often asked, if ice is insulating, and we want our freezers to stay cold, shouldn't we keep the ice?  Shouldn't a frost-and ice-filled freezer use less energy?

The answer to this is no.  Ice build-up negatively impacts freezer performance and energy consumption.  But this week, we're not going to tell you why.  We're asking you to tell us why, for bonus points!

Write to us at info@mygreenlab.org with your answers. Anyone with the correct answer - in your own words, don't just send us a link to a website please - will receive 3 extra bonus points on the Freezer Challenge score sheet.  We will publish the best answers in our next blog post.

​Stay tuned...