In a traditional heap it can often be more of a struggle to maintain high temperatures due to the open-nature of the composting pile where heat can be lost quite easily. Carpet is a method traditionally advised as a way of helping to prevent this heat loss. By adding a square on top of the pile, a piece of carpet will allow air into the pile yet stop it drying out; it is also incidentally a good way of recycling a piece of old carpet!
The HOTBIN however doesn’t require any additional insulation. The unit itself is fully sealed preventing heat loss and the walls are made from a highly insulating material called expanded polypropylene.
If carpet was placed on top of the waste inside the HOTBIN it would do the opposite of its effect in a cold heap and would restrict airflow preventing the bacteria working efficiently. Moisture inside the HOTBIN is also naturally higher in the HOTBIN so there is very little chance of it drying out.