design for a sustainable future
The amount of light we have in our houses has a big impact on our well being. Light and airy buildings make us feel better and happier. For a long time however windows have been the reason for heat loss and wasted energy.
In the 17th century, glass manufacturing technology advanced and for the first time it was possible to produce larger window panes which were stable enough to protect against the elements and let the light in. Around the same time the first sash windows were invented and used in Holland, England and France.
In England this innovation found its first mass application during the Georgian era. A large number of big windows was one way to show off wealth and prosperity. As a consequence by the end of the 17th century a window tax was introduced. The government took the number of windows as a measure of income.
Since the invention of glazing it has had a profound impact on our culture and the way we live. Whilst the facades of many corporate buildings are now almost completely glass, here in the UK many residential developments have moved back to small windows often in a retro style with the assumption that it is more energy efficient. The Georgians and Victorians who opened up their houses as much as possible, would not have approved of such an approach.
Just as in the 17th century, glazing innovations now give us new opportunities. Innovations have led to a massive reduction in heat transmission loss through the glass. A standard Victorian brick wall has a u-value of 2.0, a Victorian sash window has a u-value of 5.0, whereas windows built to a modern Passivhaus standard have u-values of 0.5 to 0.8. Now that glass quality is so good, the window frames have become the energy weak point. However double glazed windows with an overall u-value (glass and frame) of 1.2 are available at reasonable prices.
There is no reason why we should not let the light into our lives, keep warm and protect the environment at the same time.
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