What is ‘heat transfer’?
Heat transfer is the term used to describe the amount of heat a material will allow to pass through it from one side to the other. As related to doors, this refers to how much heat a door can lose when heated from one side only as would be the case for an exterior facing door such as the front door. Having a high insulation rating on these doors will save a significant amount of heat loss from occurring.
What affects heat transfer in a door?
The biggest decider in how much heat is lost through the door itself is the material it is made from. Thicker, solid materials will hold heat better than hollow or lightweight ones, wood is generally better than glass or metal but can face stiff competition from UPVC and fibreglass which have other added advantages over wood. Glass has seen recent improvements in technology which can enhance its thermal insulation properties fourfold over non-treated standard glass.
Another factor in determining heat loss is where the door is located. Direct exposure to the windward side of the weather will reduce the temperature outside the door more than other externally facing doors. In these cases, a storm door or other screen door can reduce the door’s direct exposure and cut down the resultant heat loss.
What else can be done?
Ensuring that the gaps between your door and door frame are properly sealed can help a lot. To this end, weather strips, door sweeps and draught excluders can be of assistance to make sure the door has no heat loss around the sides.