The problems with windows
13 March 2008
Windows are a major factor in wasting energy in summer and contributing to an organisation's carbon footprint
The problems with windows Government Departments are required by 2011 to meet the target of reducing absolute carbon from fuel and electricity used in buildings by 12.5%, compared to 1999. Windows contribute to a building’s carbon footprint – yet there is a simple remedy available.
Against this backdrop there is window glass – millions of panes of it in just about every local authority building and certainly in every school. As essential as it is to provide daylight, window glass is the most inefficient building material when it comes to energy loss. If you mention energy loss and windows in the same sentence people naturally think about winter and heat loss through glass. However, this article focuses on energy wastage in summer and it also touches on important areas of ‘daylighting’ and the work/study environment.
Heating and cooling represents 65% of the energy consumed by buildings. A lot of focus and resource goes into improving the performance of buildings in winter with insulation, heating controls, etc. But comparatively little attention is paid to what happens in the warmer months when the sun is shining.
So what does happen? About 90% of sunlight travels through glass in windows causing problems with glare on screens and heat gain. The temperature inside buildings increases and people switch on cooling devices, which wastes energy. Some newer buildings have the benefit of air-conditioning which, because it derives its energy from fossil fuels, and because it is one of the least energy-efficient ways of controlling temperature, increases the building’s carbon footprint.
Thermal image based shows the effect on room temperatures when an open topped blind system is subjected to 660W/m2 of incident solar heat for 30 minutes. People close blinds to avoid the sun’s direct heat. However, though closing blinds takes away the sensation, the heat is still entering the room and internal temperatures will rise.
According to the Building Research Establishment (BRE) solar gains in a glazed building can account for ten times the heat generated by equipment or lighting. In one hour a person gives of about 8W of heat energy per square metre, similar to a computer, whereas a window representing 40% of wall space on a South facing elevation can transmit 63W of heat to a square meter of floor space. Unfortunately, closing blinds also affects the natural daylight which is so essential to aid the work and study process as illustrated by research undertaken by Hershong Mahone Group which showed that a group of people learning under most natural daylight progressed 20% faster than those subjected to the least daylight. Very often when blinds are closed, supplementary lighting is switched on which uses energy and adds to the building’s carbon footprint.
Glare is a bigger problem than you might think with 75% of people that work on computers suffering from some kind of strain – and the largest contributor to this is glare. Add heat gain and you have an environmental cocktail that affects performance as borne out by a study in the USA which registered a reduction in productivity of 40% at 75°F compared to 68°F. Solar control window film can make a significant difference to internal temperatures reducing the need for energy consuming cooling devices
The net result is high levels of energy are used in summer with a negative affect on carbon footprint. Ironically, a lot of this wastage could be limited using a very simple principle: Keep the heat and glare out of the building.
The installation of Solar Control Window Film filters out up to 75% of the heat and glare. It is a convenient solution as it can be installed on selective windows with little disruption to activity. And right from the start it improves the work/study environment and neutralises the organisation’s carbon footprint. High technology window films exist which have very high levels of visible light transmission and yet can measurably reduce transmitted heat and glare. They are available from OGC Buying Solutions framework supplier Durable Limited.
This article has focused on summer – but certain window films also have insulation properties that reduce up to 30% of heat loss in the winter”.
Overall, it is a cost-effective solution that improves the work and study environment, makes it safer, increases productivity and is carbon neutral. Visit www.theproblemwithwindows.co.uk for more information or call Durable on 0870 240 2480.
Other Press Releases By This Company
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- 27/10/2014 - The dangers from retail glazing
- 06/10/2014 - Toughened glass may not be as tough as you think
- 06/10/2014 - Guard against spontaneous breakage of glass
- 07/02/2011 - Durable offers free help on Regulation 14
- 07/02/2011 - Durable offers free help on Regulation 14
- 16/06/2010 - When it comes to windows is your organisation a carbon footprint...
- 13/05/2010 - Are you a summer carbon saint or sinner?
- 13/05/2010 - Cooler workplace for free
- 13/05/2010 - Pay-back time for FMs
- 10/04/2008 - Heat and glare
- 10/04/2008 - Heat and glare for Hospitals
- 10/04/2008 - Heat and glare for Schools
- 10/04/2008 - Carbon footprint
- 10/04/2008 - Energy loss & carbon footprint for Hospitals
- 10/04/2008 - Energy loss & carbon footprint for Education
- 08/01/2008 - Found in thousands of schools but is window film being used to maximum effect? Part 3.
- 08/01/2008 - Found in thousands of schools but is window film being used to maximum effect? Part 2.
- 08/01/2008 - Found in thousands of schools but is window film being used to maximum effect? Part 1.
