Category: Energy efficiency – windows

Is triple glazing worth the extra expense in the UK?


With the current focus on energy efficiency, and many homeowners replacing their old inefficient windows – Iis triple glazing worth the extra expense?

The PassivHaus Institute tested surface temperatures on various forms of glazing when the internal air temperature is designed to be at 21°C:

Next to a single-glazed window, the internal surface temperature is around 1°C.
Next to a double-glazed window (circa 2000), the temperature is around 11°C.
Next to a modern, energy-efficient double-glazed window, the surface temperature is 16°C.
Next to a triple-glazed window the temperature is 18°C.

So whilst triple glazed windows performed better than modern double glazing, it was a relatively small difference, and something worth considering when comparing quotations.

Read article in Homebuilding and Renovation “Does triple glazing make sense?

Conclusion It is certainly worth replacing single-glazed windows. Whether you want to go for double or triple glazing will really depend on how much you can afford and how well insulated the rest of the house is. There is little point in adding triple-glazing if there is a lot of heat loss from uninsulated solid brick walls.

In June 2014 the UK government launched the Green Deal Home Improvement Fund that includes a grant for replacing single glazed windows with double or triple-glazed windows and solid wall insulation. For more details about the Green Deal Home Improvement Fund click here

Also read the Centre for Sustainable Energy (CSE) leaflet on Energy efficient glazing


Improving the thermal performance of traditional windows

Based on research conducted by Dr Paul Baker of Glasgow Caledonian University (GCU) for Historic Scotland resulted in a report “Improving the thermal performance of traditional windows”. The report summarises the results of research on the thermal performance of traditional windows and methods of reducing heat loss carried out by the Centre for Research on Indoor Climate & Health, Glasgow Caledonian University (GCU) on behalf of Historic Scotland. Whilst most of the work was laboratory based using a sash and case window, some in situ measurements were carried out in a tenement in Edinburgh. Historic Scotland carried out a series of thermographic surveys to complement the thermal performance tests.

The report has concluded that:-

Laboratory measurements of the U-value of a traditional sash and casement window showed that there was no significant difference before and after draughtproofing of the window. The whole window U-value is 4.4 W/m2K. 72% of the heat loss through the window will be via the single glazing.

The airtightness of the window was improved considerably by draught proofing, reducing the air leakage by 86%. The window is tighter than the recommended 4000mm2 trickle vent for domestic new build.

All the options tested in the GCU Environmental Chamber reduce the heat loss through the glazing. Shutters are the most effective option of the traditional methods, reducing heat flow by 51%. By insulating the shutters heat loss can be reduced by 60%. Further improvement would be possible with a purpose designed set of shutters. Improved blind designs also have the potential to reduce heat loss.

High performance secondary glazing and replacement double glazed panes offer improved thermal performance throughout the day. Careful installation of the secondary glazing also results in improved air-tightness.

All the options offer improved thermal comfort due to higher surfacetemperatures compared with single glazing alone.

The in situ U-value measurements confirm in practice the performance oftraditional shutters and show the potential benefits of low emissivity glazing in a secondary glazing system.

Effect of the options on U-value
Effect of the options on reduction in heat loss through the glazing


U‐value (or thermal transmittance co‐efficient) is a measure of how much heat will pass through one square metre of a structure when the temperature on either side of the structure differs by 1 degree Celsius. The lower the U‐value, the better is the thermal performance of a structure. The U‐value is expressed in W/m2K.

Energy Heritage: a guide to improving energy efficiency in traditional and historic homes

This guide provides options for improving the energy efficiency in traditional and historic homes. It addresses the following questions:-

  • What issues affect energy efficiency improvements in historic buildings?
  • What opportunities exist to enhance historic homes?
  • What lessons can be learned from other experiences?

It includes a case study of a project carried out in an 1820s tenement building (a traditional Scottish dwelling type with a common stair) in Edinburgh, Scotland.



Further details

Download the Full Report: – Energy Heritage: a guide to improving energy efficiency in traditional and historic homes

Childrens cold homes misery ‘unacceptable’, warns leading health expert

Cold British homes that increase the risk of mental and physical illness in children and young people are unacceptable and avoidable, warns public health expert Professor Sir Michael Marmot in a new report by his UCL research team for Friends of the Earth launched on 12 May 2011.

Friends of the Earth is calling for the Government to protect people’s health and help slash the UK’s carbon footprint by leading a nationwide refurb of heat-leaking British houses through legislation in its new Energy Bill, currently being debated in Parliament.

Professor Sir Michael Marmot said:

“Upgrading this country’s cold homes would be a double win – improving people’s health and protecting the environment. The evidence is certainly strong enough to recommend action.”

Friends of the Earth is calling for a Warm Homes Amendment to the Energy Bill requiring the Government to produce a strategy to fully insulate enough homes to tackle fuel poverty and climate change. More than a quarter [27 per cent] of the UK’s carbon emissions come from our homes.

Full press Release:-

Friends of the Earth: Childrens cold homes misery ‘unacceptable’, warns leading health expert.

Full Report: –

‘The Health Impacts of Cold Homes and Fuel Poverty’

How to reduce energy consumption in period homes

Simple draught-proofing may be all you need to keep the heat in, but care also needs to be taken with windows. Chris Wood, head of building conservation and research at English Heritage (EH), fears that the energy-saving lobby is encouraging huge numbers of owners of Victorian and Georgian houses to have eco-makeovers, and that thousands of lovely old windows will be lost for ever. This has been exacerbated by a marketing drive from double-glazing salesmen offering plastic-framed units as energy-savers.

‘Many original timber sash windows have lasted more than 200 years, and are capable of lasting another century,’ comments Dr Simon Thurley, EH’s chief executive. ‘It’s a waste to throw them away unneces-sarily.’ Research carried out on windows rescued from a skip by EH shows that they keep heat in much more efficiently after some repair.

Full article:-

How to reduce energy consumption in period homes | News – Property News, News from the Countryside and Culture | Houses for sale, properties for sale – Country Life.