When the lid opens, the air in the container approaches outside temperature within minutes. The product does not warm at that rate, because heat travels slowly from the surface to the centre. A large, massive, well-packed product holds out far longer than small pieces in thin packaging, which is why the answer to how many minutes lies in the product itself.
The loss builds up. One ten-minute opening is made up: once the lid closes the air cools quickly thanks to the plates, but the capacity the plate spent does not return. Repeated five times in one round, the openings exhaust the plates and the last drops go out warm. Each instance looks small, so nobody notices.
To shorten the time the lid stays open:
- know which parcel you are taking before the lid opens
- do the paperwork with the lid shut
- do not open the container lid while the vehicle door is open, so the two losses do not stack
- move the container into shade when a long wait is coming
