Passive Thermal and Humidity Behaviour of Steel and Insulated Shipping Containers in a Subtropical Climate

Container Performance Research Series, Report 1. Industry Research Report, Version 1.0. By Andreas Atrott, Containerbase Pty Ltd. Field study at Hemmant, Brisbane, 04-11 November 2025. This industry research report has not yet undergone formal academic peer review. External technical review is invited.

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Summary

This study presents a simultaneous, one-minute-resolution field comparison of five 20-foot shipping containers of differing surface colour, ventilation and insulation, together with a radiation-shielded external air reference, under shared subtropical exposure in Brisbane, Australia, over eight days in November 2025. The measurements show that surface colour (albedo), rather than ventilation, is the dominant driver of midday peak temperature. Dark steel units reached roughly 8 to 9 K higher peak temperatures than the cream unit, while ventilation influenced the evening cooling rate and humidity dynamics but had little effect on the peak. The insulated reefer stayed coolest and most stable throughout. An absolute-humidity analysis further shows that the lower midday relative humidity in the hotter, ventilated units reflects a temperature effect rather than genuine moisture removal. The full dataset and analysis code are openly available.

Key findings

• Dark steel containers ran about 8 to 9 K hotter than the cream unit at the midday peak, with a day-blocked bootstrap 95 percent confidence interval that excludes zero.
• The two dark units (anthracite with 18 vents, basalt with 10 vents) were not statistically distinguishable at peak, so a higher vent count did not lower peak temperature under these conditions.
• The insulated reefer was the coolest unit on every measurement day and ran about 2 K below the external air peak.
• Ventilation increased the evening cooling rate and relative-humidity cycling but had a negligible effect on the midday peak temperature.
• The lower midday relative humidity in the hotter units was a temperature effect, not genuine moisture removal, confirmed by an absolute-humidity analysis.

Methodology

Internal air temperature and relative humidity were logged at one-minute intervals in each container using Govee H5179 loggers (accuracy 0.3 C, 3 percent RH), alongside a radiation-shielded external reference and Bureau of Meteorology solar-exposure data. The observation day was used as the unit of analysis (six full days), because one-minute samples are strongly autocorrelated and are not independent. Effect sizes were estimated with a day-level bootstrap (10,000 resamples). Full methods, assumptions and the analysis script are included in the open dataset.

Download and data availability

Data availability: The underlying minute-resolution datasets, the analysis code and figure-ready aggregates are openly available under a CC BY 4.0 licence at Zenodo: https://doi.org/10.5281/zenodo.21466036

Cite this dataset: Atrott, A. (2026). Passive Thermal and Humidity Behaviour of Steel and Insulated Shipping Containers in a Subtropical Climate: Multi-Container Field Dataset (Brisbane, 04-11 November 2025), Version 1.0 [Dataset]. Zenodo. https://doi.org/10.5281/zenodo.21466036

About the author

Andreas Atrott is the founder of Containerbase Pty Ltd (Hemmant, Queensland, Australia) and conducts applied field research on the thermal and humidity behaviour of shipping containers in subtropical climates. ORCID: 0009-0007-9305-8058. Contact: andy@shipping-containers.com.au