The two types in one paragraph each
Active boxes carry their own refrigeration unit. You set a temperature and the unit holds it for as long as it has power, from mains, a battery or the vehicle. Our LMS980 mobile cold chain box and 12/24 V car fridges are active.
Passive boxes have no machinery. Insulation slows the heat coming in, and ice, gel packs, dry ice or phase-change material (PCM) plates absorb it. When the coolant is used up, the temperature starts to rise. Our fish tubs, cooler boxes, FRP medical boxes, sample transport box and EPP folding boxes are passive.
Side by side
| Question | Active box | Passive box |
|---|---|---|
| How is the temperature held? | A compressor unit cools to a set point | Insulation plus ice, gel packs, dry ice or PCM plates |
| How long? | As long as power is available | Hours to days, fixed by the coolant and the weather |
| Can it pull warm goods down? | Yes | No. Goods and coolant must be pre-conditioned |
| Can the set point change? | Yes, at the control panel | Only by changing the coolant |
| Power needed? | Yes | No |
| Weight and purchase cost | Higher | Lower |
| Running cost | Electricity and service | Coolant conditioning and handling on every trip |
| What can go wrong? | Loss of power, unit fault | Trip longer than planned, too little coolant |
Five questions that settle most cases
1. How long is the trip, including delays?
Plan for the longest realistic time, not the average. If the goods may wait on a dock over a weekend, a passive box sized for 24 hours will not be enough. An active box on mains power does not care how long it waits.
2. How narrow is the allowed temperature range?
Frozen food must stay at or below −18 °C. Many medicines must stay between 2 °C and 8 °C and must not freeze. Narrow ranges over long times favor an active box, or a passive box with PCM plates matched to the range. Plain ice is fine where the limit is simply "keep it cold".
3. Is power available on the route?
A van with a 48 V battery or a depot with sockets makes an active box easy to run. On a small boat, at a field site or in air freight, passive is often the only practical choice.
4. Do the goods go in warm?
Only an active box can remove heat from a warm load. In our own logger record, an empty active cabinet starting at +24.3 °C reached −18 °C in 41 minutes. A passive box can only hold what it is given, so the goods must be pre-cooled.
5. How will the box come back?
Return freight is a real cost. Folding EPP boxes go back flat. Large rotomolded tubs and active boxes are assets that should stay in a closed loop between known sites.
Typical choices
- Multi-drop frozen and chilled delivery in an ordinary truck: active boxes at different set points.
- Fish from vessel to processor: large passive tubs with ice.
- Clinical samples across a city: a passive transport box with coolant packs.
- Medicines to a site without power: a passive FRP box with PCM plates.
- Grocery and meal delivery: folding EPP boxes, with coolant packs for chilled orders.
Not sure which type fits? Send us the product, the temperature limits, the longest trip time and the power available on the route. We will tell you which box we would use and why.