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An obvious consideration may be the importance of air tightness in a property for preventing increased energy usage and rising energy bills.  Adequate door seals are the key to retaining heat in a property.  Masterdors have two compression seals, one in a concealed rebate that goes all round the face of the door, and a brush pile, all in a double rebated frame.  Many door manufacturers quote conduction (calculated as u-values) as the key factor for consideration but the most important aspect for reducing wasted energy usage is airtightness.  Although manufacturers of door sets submit their products for testing to PAS23-1:1999 and the tests do include air permeability (to BS6375), there is no requirement to achieve a certain level.  Some manufacturers do not even achieve a recordable air permeability level, but still receive a certificate of testing.

To ensure housebuilders take air permeability seriously, we undertook an investigation into how wind speed levels affected energy costs through heat loss and Leeds University validated the overall test results. 

Initial testing focused on how heat loss through door sets can be caused by either conduction or by convection through air leakage. 

The results revealed that heat loss through conduction is only part of the total heat loss and will not carry the same significance as heat loss through draughts due to poor sealing. 

When assessing and specifying door sets, architects and housebuilders often take into account u-values but not necessarily sufficient notice of air permeability which, as the results show, is critical to reducing heat loss and keeping out the extreme weather. Another part of the Leeds University review considered how heat loss could be converted into monetary terms and how the heat loss cost per day builds up with increasing wind speed.   The results showed that wind speeds of just 5mph can result in significant additional cost – roughly 8p per day.  Typical wind speeds in Leeds average 28mph which would equate to 45p per day in winter months.

For the sake of the planet, it is important that the industry is aware of the discrepancies of product performance and we see no reason why a door set should leak heat if it has been designed, made and fitted correctly.