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We conducted a like-for-like thermal performance comparison between WOOLPACK TB Pharma+ and a conventional EPS shipper to assess temperature stability under identical conditions.
Why thermal performance testing matters in pharmaceutical cold chains

Why thermal performance testing matters in pharmaceutical cold chains

In pharmaceutical cold-chain logistics, thermal performance isn’t theoretical, it’s measured in hours, excursions, and risk.

To better understand how insulation systems perform under extended duration conditions, Planet Protector Group conducted a like-for-like thermal comparison between a conventional EPS shipper and WOOLPACK using our high-performance TB Pharma+ liners.

The objective, to compare thermal hold time under identical refrigerant loading, so that any performance difference could be attributed to insulation efficiency and system design.

Thermal test setup and methodology

To ensure a fair and meaningful comparison, both configurations were tested under the same conditions.

Key test parameters included:

• Total Phase Change Material (PCM) mass: 4.25 kg in each system
• Comparable gel packs to those used in the existing system
• Identical loading conditions
• Continuous temperature monitoring over 120+ hours

Importantly, the PCM quantity used in the EPS shipper was deliberately matched to the WOOLPACK configuration. This ensured the results reflected insulation performance rather than refrigerant bias.

Reference photos of the test setup and gel packs were captured as part of the process.

Thermal performance test results

The difference in thermal performance was clear.

WOOLPACK (TB Pharma+ liners):

• Maintained internal temperatures below 5 °C beyond 120 hours

Conventional EPS shipper:

• Exceeded 5 °C at approximately Day 3 + 10 hours
• Reached 18 °C at the 120-hour mark, despite using the same PCM mass

This represents a significant extension in thermal hold time when using WOOLPACK under identical refrigerant conditions.

What the results tell us

The key takeaway from this testing is why the performance differed.

The improved hold time was not achieved by adding more refrigerant. It was driven by:

• Insulation efficiency
• System design
• The thermal properties of natural fibre insulation

When refrigerant loading is controlled, insulation performance becomes the critical variable and this is where WOOLPACK demonstrated a clear advantage.

Implications for pharmaceutical cold chain logistics

Extended thermal hold time provides meaningful operational benefits, including:

• Reduced risk of temperature excursion
• Greater resilience during delays or unexpected dwell times
• Improved confidence in longer or more complex distribution routes
• Potential to optimise refrigerant use without compromising protection

For pharma teams managing compliance, product integrity, and logistics risk, these differences can materially impact outcomes.

A data-led approach to sustainable performance

This testing reinforces that sustainability and performance do not need to be trade-offs.

WOOLPACK’s natural fibre insulation delivers measurable thermal performance improvements while supporting circular, lower-impact packaging systems.

We’re proud of what these results demonstrate and continue to invest in transparent, data-led testing to support customer decision-making.