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Achieving energy efficiency is becoming an ever more onerous requirement for both building designers and homeowners.

However, many fabricators are concerned that offering an ‘A’ rated window can result in a product that customers perceive as too expensive. Here, Martin Saunders, Sales Director at Eurocell, takes a look at how the company set about developing a better value ‘A’ rated window system.

“Products that have a reduced impact on the environment, or help improve the energy efficiency of a building, need to be cost-effective if they are ever to be adopted widely in the market. For some time, ‘A’ rated windows have been available to help customers achieve better thermal efficiency and therefore reduce the environmental impact of a building. However, the issue facing fabricators is that developing an ‘A’ rated window requires a fair amount of resource as well as producing a product that commands a significant price premium.

Centre and Whole window U Values
On ‘A’ rated windows, it is the sealed unit that adds most to the cost. We therefore knew that if we could improve the thermal performance of the profile system we could reduce the need for these expensive glass specifications. Improving the thermal performance of the profile system is important because there are two methods of measuring a window’s U value. As such, when your customer asks about a window’s energy efficiency, it is therefore worth clarifying whether they mean the ‘centre pane’ or ‘whole window’ U value. Although it is acceptable to use the centre pane, or glass, U value, it has to be much better than the whole window U value, which takes into account the frame as well as the glass. Current Building Regulations require a whole window U value in the range of 1.8 to 2.2, or a centre pain U-value of around 1.2.

Focusing on the ‘whole window’ U value, we were soon able to make progress in improving the frame’s thermal performance when we developed our new Thermalogik outer frame system. This has a six-chambered design in cross section that reduces the transfer of heat through the frame. On its own, Thermalogik represents a major breakthrough in offering value for money energy rated products because it is priced to fabricators at the same level as our standard window profile system.

This represented the first step in achieving a cost effective ‘A’ rated window. However, we finally made the breakthrough that reduced the need for higher glass specifications when we introduced our PVC-u Thermal Inserts. These are an innovative new range of inserts for window profiles made from 100 per cent recycled material, which offer better fabrication processes, improved thermal performance and up to 25 per cent cost savings on ‘A’-rated window glazed units. Cost savings are achieved because the use of PVC-u Thermal Inserts avoids the need for more expensive low iron glass. For example, the glazed unit cost savings are based on a comparison of a standard A-rated window (4mm low iron external glass, 20mm SGG SWISSPACER® V spacer bar, 90% argon filled cavity, 4mm SGG PLANITHERM® TOTAL internal glass) and a Eurocell window using PVC-u Thermal Inserts, Eurocell Thermalogik outer frames with 4mm standard float external glass, 20mm SGG SWISSPACER® V spacer bar, 90% argon filled cavity, 4mm SGG PLANITHERM® TOTAL internal glass.*

The tests we carried out demonstrated that our new ‘A’ rated window system can achieve a British Fenestration Research Council (BRFC) ‘A’ rating with an Energy Index of 9 kWh/m_/year. When the window thermal performance is measured in terms of U value, it achieves 1.2, again indicating that it is one of the best performing double glazed windows in the market.

An Energy Index of 9 kWh/m_/year indicates that the window will provide a net capture of heat over the year and only a very few products can achieve this. The Energy Index forms part of the Window Energy Ratings alongside the A-G scale on the Energy Label and indicates how much energy the window will save or lose once it has been installed. 9 kWh/m_/year means the window will make a net gain of nine kilowatt hours per square metre per year, which will contribute towards heating the home.

Communicating ‘A’ rated benefits to customers
As more fabricators begin to use our new cost effective ‘A’ rated window profile system, we are encouraging them to market the product effectively. One of the best ways of doing this is through gaining a product rating and subsequent listing on the British Fenestration Rating Council (BFRC) website. As a BFRC Certified Simulator company, we are happy to help our fabricators through this process. The advantages are definitely worth the effort as many homeowners are using the website as a means of identifying fabricators that offer energy rated windows. The ratings are given in bands from A to G, just like energy-performance labels on white goods for the home.

As a company, we believe that ‘A’ rated products should offer customers real value for money and our new ‘A’ rated window system has been designed specifically for this. It is already helping our fabricators provide their customers with a solution to reducing the carbon footprint of the UK’s housing stock. The ultimate beneficiaries will be building designers and homeowners as an ‘A’ rated product will mean that the property requires less energy to heat and therefore generates fewer carbon dioxide emissions.

Offering one of the most cost effective ‘A’ rated windows in the market now enables our fabricators to address the conundrum faced by customers – an acceptance that an ‘A’ rated window is better for the environment, but with a need to remain within budget. As the legislation around climate change becomes ever more stringent, it is initiatives that put the energy efficient products in the reach of a greater proportion of the market that will succeed.”

To find out more about Eurocell’s better value ‘A’ rated window system, visit: HYPERLINK "http://www.eurocell.co.uk", contact customer services on 0800 988 3049, or email press@eurocell.co.uk

* Source: Solaglas Limited (November 2008)