Passive vs. Active Cooling: Insulated Box Cooling for Perishable Foods

liviri passive cooling with insulated boxes

Maximize Perishable Food Delivery with Passive Cooling

Packing is crucial to the successful delivery of perishable foods. And the type of cooling mechanism you choose for staging and delivery plays a key role in keeping goods fresh.

For most companies, choices are limited to two options — active or passive cooling. Active cooling requires energy-hungry, temperature-controlled storage solutions such as refrigerated trucks, walk-in refrigerators and freezers.

The alternative is to maintain the quality of perishable goods with either ice or standalone coolant. This is known as passive cooling — a more cost-effective, environmentally preferable option that doesn’t require electricity or higher impact, gas-generated refrigeration systems.

Signs of The Time

As online ordering and shopping has boomed, the demand for grocery pickup and delivery has skyrocketed.

With the growing demand for online shopping, grocers have been running out of chilled and frozen staging space for online pickup and delivery orders. Refrigerated trucks are in high demand and very expensive. Additionally, microfulfillment distribution centers, or “hubs” — which deliver to local “spoke” grocery stores — have increased the cold-chain requirements as more and more food is transported to pick up locations.

Liviri provides proven solutions to help satisfy the growing consumer demand for passive cooling options.

Passive cooling with insulated boxes is a great substitute for active cooling options. And with the right amount of coolant coupled with proper ice management, chilled food can be kept at the Food and Drug Administration-specified temperature range for 10 to 15 hours — even in hot environments.

With economical EPP insulated boxes, the demand for refrigerated trucks, chillers and freezers is reduced, making passive cooling a much more environmentally friendly option. That’s because the energy used to maintain these cold environments has a notable negative effect on the climate.

According to Project Drawdown, the poor disposal and displacement of the chemicals used for refrigeration will be the No. 1 cause of an increase in greenhouse gas (GHG), with food waste as the third-largest contributor to GHG emissions. The combined negative GHG contribution of refrigerant chemicals and food waste is more than three times the total carbon dioxide emissions estimated by the Intergovernmental Panel on Climate Change (IPCC).

In addition to decreasing environmental impact, passive coolant shipping provides grocers and perishable food shippers more flexible staging options to get their goods out by not requiring dedicated space for active cooling. It also offers convenient door-to-door protection and convenience for consumers.

It is easy to integrate passive cooling in perishable food and grocery pickup and delivery strategies. Here are some basic guidelines for retailers interested in implementing passive cooling solutions:

1. Measure cold chain success based on when food crosses critical temperature thresholds, not by concrete rises in temperatures. 

  • Chilled food (dairy, proteins and meat) must stay below 40° F. (4.4 Celsius) per the FDA
  • Frozen food (fruits, veggies and frozen meals) start to soften at 20° F. (-6.66 Celsius)
  • Ice cream begins to melt at 10° F. (-12.2 Celsius)

Focus on staying below the temperature requirements instead of measuring how much the temperature rises inside your sustainable packaging. For example, requiring that ice cream removed from a -10° F. (-23 Celsius) freezer increase no more than 5° F. is not a realistic or necessary requirement, especially since ice cream doesn’t begin to melt until 10° F. Instead, concentrate on adding appropriate coolant and insulation to ensure ice cream always stays below 10° F. to prevent melting and the formation of ice crystals.

2. Optimize coolant load. Liviri has tested hundreds of different use cases to determine the right amount of coolant needed to achieve optimal food quality protection. The following factors impact how much coolant is needed:

  • External temperature profile. Does the product require a staging room temperature? A bump in external temperature for transport on a hot truck? (Additionally, be prepared to adjust coolant for different times of the year)
  • Cold-chain duration requirements
  • Coolant type
  • Desired state of food when it arrives to the consumer. Grocery customers expect that their ice cream and frozen foods will be delivered frozen solid. In contrast, customers who order premium beef or meal kits may want food to arrive partially thawed, so it’s ready to consume

3. Maximize direct contact with coolant. To achieve the best results with the least amount of coolant, it’s essential to sandwich food between ice packs to maximize direct coolant contact. When shipping in extreme heat, enclose goods within a box of coolant using horizontal ice packs on the bottom of the container, plus vertical ice packs on the sides, to increase cold-chain performance.

4. Use the right coolant type for the job:

  • 32° F. (0 Celsius) ice packs are best for keeping chilled and most frozen foods cold for the longest period of time — since they melt the slowest
  • 5° F. (-15 Celsius) ice packs are best for keeping ice cream below 10° F. (-12 Celsius) and frozen food below 20° F. (-6.6 Celsius) for up to 12 hours
  • Dry ice is excellent at keeping ice cream below 10° F. (-12 Celsius) and frozen food below 20° F. (-6.6 Celsius) for longer periods of time — but it can be challenging to manage

5. Pre-condition insulated box, when possible.

  • Store empty insulated boxes in walk-in refrigerators or freezers to avoid having to cool down warm totes. This enables the containers to maintain cooler temperatures longer with less ice

6. Reduce empty space in sustainable packaging. The more densely a box is packed, the longer it maintains desired temperatures.

  • Use thermal dividers to combine frozen and chilled items in the same box. Or, combine multiple orders in the same box to eliminate dead air space

7. Extend cold-chain timeframe performance by staging early morning route orders in refrigerators or freezers overnight. 

  • Ice cream with 5° F. (-15 Celsius) ice packs lasts five hours longer with over two pounds less ice when staged in a refrigerated staging area