Humidity: a key concern in cold storage


02 November 2021

Increasing pressure on the supply chain means new challenges such as humidity levels and moisture control for cold storage professionals to be aware of, says Ryan Stanley, moisture control specialist at Aggreko Northern Europe.

It seems as if the word ‘unprecedented’ is overused, but it most definitely applies to the strain food and beverage supply chains are currently under. Exacerbated by the twin impacts of new trading arrangements and labour shortages in the logistics sector, large quantities of frozen and chilled goods now remain in cold and chilled storage that is rapidly filling.

This situation is further compounded by the approach of seasonal pressures associated with the end of the year, including Christmas, as storage systems already at capacity require additional duty to ensure normal operations in rising temperatures. Consequently, many companies and storage providers have struggled to maintain refrigeration provision requirements, leading to raised risks of expensive product spoilage.

Without the cashflow required to finance permanent installations that could alleviate coronavirus-related issues, companies can find themselves in an ever-worsening situation they can’t afford to escape.

Continuing pressures

Exacerbating things further is the fact that while pandemic-induced disruption remains very much front-of-mind, ongoing pressures around maintaining efficiency and productivity continue. In fact, the tightening expenditure restrictions caused in the wake of COVID-19 means that companies with cold storage are having to do more with less to improve process efficiency, limiting obvious opportunities for improvement at a time they can ill-afford to make losses.
Yet though the current landscape may seem hostile for cold storage operators in the food and beverage industry, it can be argued that the sector is well-placed to weather these temporarily trying conditions. Indeed, by approaching issues such as equipment hire from a new angle, companies can put themselves in a better place to react to coronavirus-induced pressures, including labour shortages.

Flexible futureproofing

Though investing in a permanent cold storage installation might seem logical for site facilities and process managers, this strategy is arguably ill-suited to the food and beverage industry. This is because while a permanent installation provides consistent performance levels, it may not be adaptable enough for a sector where short-term contracts seasonal produce cycles and short-term shocks such as the existing labour shortage are the norm. Inflexible permanent installations are less able to adapt to these concerns, and may soon become oversized, inefficient and no longer fit-for-purpose when that contract expires. 

With that in mind, site owners and operators can better futureproof their business by taking a strategic, outcome-based project approach to equipment specification. As well as allowing companies to circumvent capex restrictions and access up-to-date, highly efficient cooling systems, hiring solutions lets businesses build a degree of modularity and flexibility into their cold storage operations.

Hidden variables

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However, ensuring additional capacity only addresses half the problem. Indeed, the situation facing food and beverage supply chains cannot be overstated, with the Road Haulage Association recently announcing a shortfall of 100,000 heavy goods vehicle drivers in the UK from a pre-pandemic total of roughly 600,000. Consequently, more products and produce than ever is remaining in storage without a large enough workforce to mobilise it.

Yet with these spaces rapidly filling up, further hidden variables must be addressed if warehouse owners and operators are to avoid product spoilage or non-acceptance from retailers, including humidity control. While this is always a concern, increasing stock levels can further affect humidity levels, leaving entire stores at risk. Specifically, storage areas that are at-or-over capacity may encounter problems concerning insufficient or inconsistent air flow in all places within the store, leaving certain products at a higher risk of spoilage.  

Considering that air within these stores can be too cold – down to -27°C – to hold any moisture, a dew point can be reached. This in turn means that as the air cannot hold any more water in gas form, condensation and ice can build up on floors, ceilings, entryways and on the products themselves. Not only is this a health and safety risk for warehouse staff, it can also pose issues once affected items leave cold storage and are transferred into a chilled or ambient air environment.

Product condition concerns

These concerns are twofold – firstly, the water in the air that has transferred onto produce within the store may ingress into products as it cools down, compromising their quality to an extent that retailers further down the supply chain will not accept them. Packed items may be similarly affected due to the hydroscopic materials present in packaging, which will retain water that has not been physically removed from the storage space, resulting in visible water damage on the pack itself. 

With food displayed on supermarket shelves subject to rigorous standards concerning presentation, this sort of impairment would lead to non-acceptance on their part, at major cost to warehousing businesses. These issues, combined with the greater financial impact larger quantities of damaged, stockpiled goods can have on warehouses and manufacturers, makes it clear that moisture control strategies are required to ward off prohibitively expensive losses. 


One such way to alleviate these risks is through the use of dehumidification equipment alongside cooling solutions to control water vapour within cold storage facilities. These manage excess water vapour within store rooms by drawing air from the environment over a coil and reducing to a very low temperature via a refrigeration system. This essentially cools the air below the dew point temperature so that it condenses and drains away. 

Crucially for cold storage, this equipment can be combined with post-cooling techniques to mitigate any rise in air temperature that may be caused through the dehumidification process. This means air flows can be maintained at optimum humidity and temperature conditions even as stores continue to fill, as strategies are in place to ensure air within the facility remains dry and cool at all times. 

Yet though eliminating such uncertainty is key to maintaining stock integrity, it must also be noted again that this period of intense disruption will not be permanent. As such, purchasing dehumidification equipment now, only for it to become redundant later, could represent an unacceptable expense for companies whose budgets have already been slashed by the pandemic. Put simply, temporary problems do not require permanent solutions, so equipment hire treated as an ongoing opex cost may therefore be the best way forward for these organisations.

In conclusion, the disruption caused by labour shortages is everywhere, and poses challenges for both the food and beverage and cold storage sectors. Yet by taking an innovative approach to equipment hire, companies can ensure their cooling system can be temporarily upgraded to efficiently meet current stockpiling demand while reducing costly product spoilage risks with an effective moisture control strategy.