US Patent 7597129 Door closure system

A door structure, said structure for use particularly, although not necessarily exclusively, to selectively close an opening between a first environment which is at a temperature which is lower than the temperature of the environment on the opposing side of the opening. The door is provided with a structure so as to define a cavity therein into which air is caused to flow. The door has formations and a structure so as to encourage uniform air flow through the cavity and hence prevent or minimise the creation of condensation and/or frost on the door structure.