The insulation efficiency of glazed doors and windows in buildings is worked out by using a u-Value.
The lower the u-Value, the more efficient they are are at keeping a property warm by reducing
the amount of cold air from outside getting into the home and reducing the amount of warm air in the
Below we detail the current requirements for private dwellings that were introduced in recent years by the Government.
a - The Building Regulations 2010 - Amendments to the Approved Document LIB; Conservation of fuel and power in existing dwellings (2010 edition) published November 2013, coming into effect April 2014.
Windows, roof windows and roof lights - u-Value 1.6W/m2K
Doors - u-Value 1.8W/m2K
b - The Building Regulations 2010 - Approved Document L1A: Conservation of fuel and power in new dwellings, 2013 edition
- Windows, roof windows, glazed roof lights and glazed doors - u-Value 1.4W/m2K
- Semi-glazed doors - u-Value 1.2W/m2K
Therefore, you will need to make sure that any replacement windows and glazed doors meet the above
Planning permission is not normally required for replacement windows and doors as long as certain criteria are met.
Such permission would be required if the local council issued an Article 4 Direction that withdrew permitted
development rights or you would need listed building consent if you live in such a property.
Under the Building Regulations section above, we provided you with information about u-Values relating to
glazed windows and doors. We thought you would find it interesting to know what the maximum u-Values are
for certain other parts of new built properties in comparison to glazed windows and doors: -
External walls - 0.18W/m2K
Roof - 0.13W/m2K
Floor - 0.13W/m2K
As you can see, there is a significant difference.
Therefore, it would make sense that, as well as having replacement windows and doors fitted,
other parts of your home are well insulated to maximize the retention of heat in your property.
So, you should also consider the likes of loft and cavity wall insulation.
It is also worth pointing out that a window with single panes of glass has a u-Value of over 5.00W/m2K.