WINDOWS: A JOURNEY FROM DRAUGHTY SINGLE GLAZING TO VITAL THERMAL BARRIERS

Turn back the clock to 1966. LHC is formed, Harold Wilson’s Labour Party is in power and trade union barons exercise formidable control over the country’s industrial output. It’s also the year England wins the World Cup.

Efficient fabrication techniques, window design and replacement expertise

Much of the country’s council housing has fallen into disrepair and is beginning to be replaced with high density housing and tower block living.  

Windows and doors are predominantly timber, but aluminium is beginning to become popular, after marketers claim it is “virtually maintenance free”.

Single glazed units are the norm with energy efficiency barely being given a second thought. These “modern” units were considered a huge improvement, keeping out the cold better than their draughty timber or steel predecessors.

Note the term “keeping out the cold” as opposed to “keeping in the heat”.  This was the thinking until the early ‘70s. However, when the oil crisis took hold in 1973, it led to the realisation that a more energy efficient approach was required.

The acceleration of public sector house-building continued throughout the seventies, with virtually no domestic refurbishment projects being undertaken.

Window designs became more energy efficient, with sealed glazing units, which commonly comprised of two panes of 4mm annealed glass with a nominal 6mm to 10mm air gap.

Rubberised draft stripping is introduced on timber sashes and brush pile on aluminium. However, weatherproofing efficiency isn’t great.

Throughout the seventies old timber or steel windows are replaced with aluminium units. These are developed from anodised finishing to the more visually attractive white powder coated frames.

Coupled with the conservative government’s moratorium (initiated by Michael Heseltine) on new council house building, more and more refurbishment projects were being rolled out into the 1980s.

Efficient fabrication techniques, window design and replacement expertise meant that large swathes of council housing could now be “re-windowed”, quickly and comparatively inexpensively.

During the 1980s, PVC-U systems were being introduced into the UK from Germany. These were larger in profile size than the aluminium and timber frames they were to replace.

As profile designs became slimmer and more appealing to architects and planners, the use of PVC-U windows and doors exceeded other materials. Further investment, together with efficient production techniques, saw PVC-U products become the UK’s most widely used window and door material through the 1990s.

In 2002, new Building Regulations for thermal efficiency and compliance with a means of escape in the case of a fire and ventilation came into play. The Kyoto Protocol, to reduce greenhouse gas emission, was adopted in 2005.

Now minds were concentrated on the thermal efficiency the external envelope of buildings – not least the windows and doors.  

In today’s marketplace, all three materials nestle comfortably with each other.  It’s widely acknowledged that government legislation will continue to demand greater thermal efficiencies.

In response to this challenge, considerable research and scientific progress has been made in the development and design of glass and glazing units, thermally efficient profiles, hardware operation and weatherproofing as well as the understanding of how to harness the internal and external heat sources.  

That’s a very long way from just “keeping out the cold” and substantially more improvement than the England football team!  

Chris Powell, LHC technical procurement consultant

This article was originally published in HABM June 2015 as part of a series of article looking back sectors LHC has been involved with since its formation in 1966.

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