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U Values & SHGC explained
May 20, 2016
When selecting timber windows and timber doors for your home or building project you will often be required to comply with certain performance values for energy efficiency. That is – you may be asked to select windows and doors with a specific U Value or Solar Heat Gain Co-efficient. In order to comply, the window system must perform to the set parameters. It’s important to note, that these values are “whole window values”, not glass alone.
The U-value is the measure of how much heat is transferred through the window. The lower the U-value the better the insulation properties of the timber window – the better it is at keeping the heat or cold out. In all cases regardless of climate zone a timber window with good insulation properties will help to improve the comfort of your home. To comply with energy reports U values must be lower than or equal to that specified in the report.
Solar Heat Gain Coefficient or SHGC is a measure of how much solar radiation passes through the window. In a cool climate, windows which have a high SHGC allow a greater amount of solar radiation to pass through, offering free solar heating for the home. Glass selection has a considerable effect on the SHGC of a window or door. To comply with energy reports, the SHGC must be within 10% of the set value.
The Timber Difference
Unlike aluminium which acts as a conductor, timber has natural insulating properties and with added energy efficient glazing, makes it to most thermally efficient material used for doors and windows.