7 tips for chilled shipping during hot summers
Short answer: in July and August, increase the amount of coolant by 50 to 100%, ship at the start of the week, seal all seams airtight and consider PCM packs or heavier insulation. At an outside temperature of 30 °C, the cooling time of the same packaging is easily a third shorter than at 20 °C.
What was a safe shipment in March can run completely differently in July. Here are seven practical tips to get your chilled shipments there reliably in summer too. At the bottom you will find a checklist and answers to frequently asked questions.
1. Double your coolant
A rule of thumb: in July and August, add 50 to 100% more ice packs than in colder months. A shipment that was fine with two gel packs in April probably needs three or four in July.
Make sure you can actually fit the extra cooling elements in the box. A full box holds the cold better than a box with a lot of air. If necessary, choose a slightly larger box or fill empty space. How to calculate the right number, you can read in how many gel packs do you need per shipment.
2. Ship at the start of the week
Thursday shipments that stay in distribution centres over the weekend are an extra risk in summer. Plan critical shipments for Monday or Tuesday.
Do you know that a parcel will be delayed, for example because of a public holiday? Then it is sensible to let that shipment wait a day. An extra day of waiting in your own cold room is cheaper than a shipment that gets too warm on the way.
3. Use airtight packaging
An open EPS box leaks heat through the seams. Seal all seams properly with packaging tape, and if desired wrap a layer of reflective insulation film around the box for summer shipments.
Also check that the lid closes properly. An EPS box is supplied as standard with a matching lid. If the lid sits crooked or product lies against the edge, a gap appears through which warm air gets in.
4. Avoid direct solar heat
Advise your drivers and distributors not to leave boxes standing in the sun. During transhipment on a site without a roof, the outside temperature of a box can quickly rise to 50 °C+.
You can also gain a lot on your side. Do not leave the pallet with ready boxes waiting outside for the carrier. Only get the shipment ready at the moment of collection, and until then keep the boxes in the shade or in a cool room.
5. Consider PCM instead of standard gel packs
Standard gel packs melt at 0 °C and then give off heat at that temperature. For products that must stay strictly above 2 °C, PCM elements (melting at e.g. 5 °C) can be a safer choice. They do not freeze your product, but do keep it cool. View our range of PCM packs.
Do you want to know how long a cold pack holds its temperature? That depends on the outside temperature, the filling and the insulation. You will find more explanation in how long does a cold pack stay cold.
6. Temporarily upgrade to heavier insulation
For the three hottest months it can pay to switch to heavier cooler boxes, for example from standard EPS to thermal boxes. The extra cost per shipment is typically €0.50 to €1.00, and you prevent many complaints and returns.
A thicker wall within the EPS range also helps. A thick-walled box insulates longer than a thin-walled one. Which variant suits your route, you can read in thermal box: how to achieve 48 to 72 hours.
7. Ship in the right way
Ask your carrier about chilled transport where available. DHL and other couriers have options for temperature-controlled transport. Often at extra cost, but worth the effort for critical shipments.
Also ask about the lead time. A parcel that is a day longer in transit than planned uses up part of your cooling reserve. Therefore always allow for a buffer on top of the expected transport time.
Checklist for a summer shipment
Go through these points before closing the box:
- Are the cooling elements fully frozen or chilled, according to the desired temperature?
- Has the product been brought to temperature beforehand? Warm product in a cold box costs a lot of cooling capacity.
- Is there no empty space left in the box?
- Does the lid close properly and are all seams taped shut?
- Is the shipment not ready on a Thursday or Friday?
- Does the carrier know that this is a temperature-sensitive shipment?
How to freeze and pack cooling elements properly is explained in freezing and packing ice packs.
Measuring is knowing: use a data logger
Whether your summer packaging works, you only know for sure when you measure it. With the first summer shipments, place a data logger in the box. After arrival you read out the temperature curve. That shows you whether the cooling reserve was ample enough or whether you need to adjust the build-up. View our data loggers.
Preferably test on a warm day and with the route you use in practice. A trial in a cool workshop says little about what happens in a delivery van or at a depot.
Frequently asked questions
How many cooling elements do I need in summer?
As a starting point, 50 to 100% more than in colder months. The actual amount depends on the outside temperature, the transport time, the box and the filling. A data logger gives the answer.
Can I combine gel packs and PCM?
That is possible, but the melting temperature differs. Gel packs are intended for 0 °C, PCM for a higher temperature such as 5 °C. Choose per product the temperature you want to maintain. If in doubt, ask for advice.
Is dry ice an option in summer?
Dry ice is another way of cooling, with its own rules for transport. First read cold packs or dry ice to see what suits your shipment.
When is it best to order my summer packaging?
Preferably before the first heatwave rather than after. If you order before 14:00 on working days, we still ship the same day.
Need help?
Not sure whether your summer packaging is up to it? Please contact our advisers via the contact page. We are happy to take a look.
Order directly
Need the right packaging straight away? View our cooling elements, EPS boxes and ice packs.
