Correct Packing Techniques for Temperature-Controlled Shipments

Why Temperature-Controlled Shipments Still Fail

When temperature excursions occur, businesses often look first at the packaging materials. Was the insulation thick enough? Were the coolant packs sufficient? Should a different packaging format have been selected?

While these questions are important, they rarely tell the full story.

Most cold chain failures occur because of a combination of operational and packaging-related factors.

Common causes include:

• Incorrect coolant placement
• Poor product preparation
• Excessive air space within the shipper
• Insufficient coolant mass
• Delayed dispatch
• Carrier disruptions
• Seasonal temperature variations
• Inconsistent packing procedures

In many cases, the packaging system itself is capable of maintaining temperature, but the way it has been packed or deployed compromises performance.

This distinction matters because businesses often respond to temperature issues by adding more packaging rather than addressing the root cause.

The result is frequently higher cost without improved performance.

The Science Behind Effective Cold Chain Packaging

Every temperature-controlled shipment functions as a thermal system.

The purpose of the packaging is not to actively cool products. Its role is to maintain the desired temperature range for as long as possible despite changing external conditions.

Three factors largely determine whether this happens successfully:

1. Thermal Mass

Thermal mass refers to the amount of cooling energy available within the shipment.

This is influenced by:

• Product mass
• Coolant quantity
• Coolant type
• Starting temperatures

A larger thermal mass generally provides greater temperature stability, but more is not always better.

Adding unnecessary coolant increases shipment weight, transport costs, handling complexity, and, increasingly, EPR-related costs.

The objective should always be optimisation rather than maximisation.

2. Insulation Performance

Insulation slows heat transfer between the external environment and the product.

However, insulation cannot compensate indefinitely for poor pack-out design.

Even highly effective insulation will underperform if:

• Coolant is incorrectly positioned
• Products are packed warm
• Excessive void space exists
• Transit durations exceed design assumptions

3. Air Movement Within the Package

This is one of the most overlooked aspects of cold chain packaging.

Large void spaces allow warm air to circulate within the package, creating temperature inconsistencies and increasing the workload placed on coolant systems.

Many businesses compensate by adding additional coolant when the real issue is packaging geometry.

A correctly sized shipper with appropriate product placement will often outperform a larger shipper carrying significantly more coolant.

The Most Overlooked Variable: Product Preparation

One of the simplest and most common mistakes occurs before the product even enters the packaging system.

Packaging maintains temperature. It does not create it.

If chilled products enter the pack-out process above their required temperature range, the coolant system must first work to remove that excess heat before maintaining conditions throughout transit.

This creates unnecessary strain on the packaging system and increases the likelihood of temperature excursions.

Best practice should always include:

• Verifying product temperatures before packing
• Maintaining temperature-controlled staging areas
• Minimising exposure during fulfilment
• Establishing documented handling procedures

This applies equally to cold chain packaging for meat products and pharmaceutical cold chain packaging.

The most sophisticated packaging solution cannot compensate for poor product preparation.

Why Coolant Placement Matters More Than Most People Think

Much of the industry debate focuses on coolant type.

• Gel packs versus water packs.
• Phase change materials versus ice.
• Reusable versus disposable solutions.

These discussions are valuable, but they can sometimes distract from a more important question: where is the coolant being positioned?

Cold air naturally sinks while warm air rises.

Understanding these thermal dynamics is essential when designing effective pack-outs.

For food shipments, common considerations include:

• Distributing coolant evenly
• Protecting products from direct freezing
• Managing airflow within the shipper
• Positioning coolant relative to expected heat gain

For pharmaceutical shipments, coolant placement must align precisely with validated pack-out configurations.

Even small changes to a validated pharmaceutical packaging system can affect qualification status and performance outcomes. This is why pack-out consistency is so important.

The best packaging system in the world will struggle if shipments are packed differently every day.