Windows account for 10% of heat loss in many homes. In this article we will look at options for improving or replacing windows to reduce those losses. We will discuss the use of curtains, shutters and blinds next month. The summer is a good time to get work done ready for next winter.
Older double glazing may be ‘blown’, in which case condensation will be visible inside. Double glazing standards changed in 2003, so older units might be worth updating if you are able to. If the frame is wood and in good condition and still fits well upgrading the glazing is better for the environment than replacing the whole units, and should be cheaper.
As always there are a bewildering number of approaches available. The areas worth considering are the glazing type, frame materials, style (eg types of openings used by the window), security, longevity, price.
The Glazing Units
The table below summarises much of this:
The data above is a compilation from many sites – and inevitably individual products will vary
Secondary glazing has considerable thermal benefits over single and in addition can significantly reduce draughts, but may mean a window cannot be opened without removing the secondary pane.
Double glazing can be narrow, ie a small gap between the panes, but a wider gap is more efficient
Triple glazing is heavy and wide, but offers very good efficiency
Vacuum glazing equals or exceeds the benefits of triple glazing but is thin enough to retro-fit into frames designed for single glazing
Frame Materials
The variations here are about material costs, production costs, longevity, ongoing maintenance and heat loss through the frame
PVC has developed significantly, now being available in different colours and with convincing grain patterns if wanted.
Window Style
This is in part about choice but can re-specified by planning, particularly in conservation areas.
Retro-fit and Conservation Area Requirements
Some areas have planning restrictions which limit the construction materials or design of windows. If the current frames are in good condition single panes can be replaced with thin double glazing (‘heritage glazing’) or vacuum units.
Doors
Doors can be made to match windows. Energy efficiency is important and each material has different ways to ensure insulation and draught proofing is maximised. The door ‘furniture’ should also be considered; for example a letter box may be unnecessary and newer style keys avoid the need to have a draughty hole right through the door.