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Laboratory Fridges, Freezers & Efficiency

Factors that influence the efficiency of laboratory fridges and laboratory freezers include:

  • The type of door
  • The refrigerant type
  • The amount of insulation
  • The capacity
  • The operating temperature

Going into further detail about each of these:

Door Type

The type of door that a laboratory fridge or freezer  has greatly affects efficiency. A solid door is constructed from outer steel or stainless steel skin, a thick layer of insulation material and an interior skin constructed of steel, stainless steel or plastic. A solid door has excellent insulation properties.

In contrast a glass door has two layers with a cavity between typically filled with an inert gas such as argon.  Double glazing has far better insulation properties than single glazing but compares unfavourably to a solid door.

To see how much difference it makes I’ll compare the 24 hour power consumption of some Liebherr laboratory fridges. The only difference between each fridge is the door type.

Laboratory Fridge Model Energy consumption / 24hr Extra % Yearly Power Use*  Yearly Savings*
LKuv1610 – Solid Door – 141 litres 0.747 kWh   $82 $29
LKuv1613 – Glass Door – 141 litres 1.010 kWh 35% $111  
         
LKv3910 – Solid Door – 360 litres 0.846 kWh   $93 $51
LKv3913 – Glass Door – 360 litres 1.315 kWh 55% $144  
         
LKPv6520 – Solid Door – 601 litres 1.775 kWh   $194 $105
LKPv6523 – Glass Door – 601 litres 2.731 kWh 54% $299  

 

The refrigerant type

Common refrigerants for laboratory fridges include R134, R600a and R290.

R134a is one of the most common gases used in lab refrigerators. It is non-flammable gas with insignificant ozone depletion potential and a somewhat lower global warming potential. All refrigeration mechanics are capable of dealing with this gas but it does use more.

R404 and R507. Blends of HFC refrigerants commonly used for medium and low temperature refrigeration applications

R600a is refrigerant grade isobutane. It is a flammable gas, with zero ozone depletion potential and very low global warming potential. The use of R600a is growing due to its low environmental impact and excellent thermodynamic performance. Downsides to R600a include that it is flammable and not all refrigeration mechanics can work with it.

R290a is refrigerant grade propane. This too is a flammable gas, with zero ozone depletion potential and very low global warming potential. The use of R290a is also growing due to its low environmental impact and excellent thermodynamic performance. Downsides to R290a include that it is flammable and not all refrigeration mechanics can work with it.

When it comes to laboratory fridges the most common choice is between R134a and R600a. Here is a comparison cost between similar sized fridges. Clearly R134a saves a lot of money in electricity.

Laboratory Fridge Model Energy consumption / 24hr Extra % Yearly Power Use*  Yearly Savings*
LKv3913 – R600a – 360 litres 1.315 kWh 55% $144 $285 to $313
FKG371 – R134a – 380 litres 4.17 kWh 217% $457  
VS400 – R134a – 400 litres 3.92 kWh 198% $429  

 

The amount of insulation

The better the insulation the better the efficiency of the fridge. The primary concern here is the door type but the insulation in the rest of the lab fridge or freezer is also important.

The capacity

The larger the lab fridge or lab freezer the more electricity will be used. So for all other things being equal you are better off getting a fridge or freezer that is the right size for your needs than to get a larger one. Unfortunately not all things are equal so it’s not uncommon to see a smaller fridge/freezer from one manufacturer use more electricity than a larger fridge/freezer from of a second manufacturer.

This table gives an idea of power use for different size lab fridges.

Laboratory Fridge Model Energy consumption / 24hr Extra % Yearly Power Use*  Yearly Savings*
LKuv1613 – Glass Door – 141 litres 1.010 kWh   $111 $33 to $188
LKv3913 – Glass Door – 360 litres 1.315 kWh 36% $144  
LKPv6523 – Glass Door – 601 litres 2.731 kWh 203% $299  

The operating temperature

The colder than a fridge or freezer operates the more energy that will be consumed. This is easily shown by comparing fridges and freezers from the same product family.

Laboratory Fridge or Laboratory Freezer Model Energy consumption / 24hr Extra % Yearly Power Use*  Yearly Savings*
LKuv1610 – lab Fridge – 141 litres 0.747 kWh   $82 $20
LGUex1500 – lab freezer -139 litres 0.926 kW/h 24% $101  
         
LKv3910 – lab fridge – 360 litres 0.865 kWh   $95 $49
LKexv3910 – lab freezer – 360 litres 1.309 kWh 51% $143  
         
LKPv6520 – lab fridge – 601 litres 1.775 kWh   $194 $263
LGPv6520 – lab freezer – 601 litres 4.175 kWh 135% $457  

* based on 30 cents per kWh