Appeal will be broad but it’s too early to predict the impact: Questions to be answered

Window Energy Ratings (WERs) become an integral part of the Part L of the Building Regulations from April. Already, several manufacturers have achieved a rating on products which will typically save around £70 in heating bills and over half a tonne of carbon dioxide emissions per year. (N.B. The comparison is when installed in a typical three bed semi-detached house with single glazing).

Richard Bawden, Trade Partnerships Manager at the Energy Saving Trust, says: ‘Our homes are responsible for 28 per cent of all UK carbon dioxide emissions and as windows are responsible for 20% of all heat loss in an average home, improving their efficiency is an important step towards combating climate change.’

The answer is a new style of high performance window that is not without controversy, because it recognises a solar gain factor in addition to insulating properties. Windows achieving a rating of C and higher can carry the Energy Efficiency Recommended logo.

The logo was developed in 2000 as a way of signposting consumers to the most energy efficient products in the market place. It is used on a number of different products including boilers, heating controls, insulation, lighting and fridges. The Energy Saving Trust has endorsed 1450 products from 76 different manufacturers.

ABC of achievements

Masterframe was the first to achieve a ‘C’ rating with its Bygone Collection, available only to preferred installers. As a dedicated PVC-U sash window specialist, the rating will no doubt help the Essex company’s pitch into this niche.

The company is certainly banging the drum: Alan Burgess, Managing Director, recently addressed specifiers and the other attendees at the recent 14 Days sustainability conference in London in November (see www.14days.co.uk).

Piper Double Glazing’s ‘A’ rating was reported last month. This window is actually a net contributor of energy, and was developed in response to an enquiry from a local authority. But the weight of the triple glazed frames raises questions about handling, as does the scheme in general. Unless installers have satisfactory quality management systems to be allowed to deglaze before installation, windows will have to be supplied fully glazed.

The triple glazed Piper window also flags up the possibility that replacement windows might be chosen that are less than in-keeping with their properties.

Speed Frame’s double glazed envirowindow is the company’s standard product for newbuild. It is the only window to have achieved a Window Energy Rating of ‘B’, and it was shown to specifiers at the September housebuilding show (www.housebuilding2005.com).

‘For the homeowner it’s perfect’, said Paul Spencer, Head of Marketing at Speed Frame. The buyers for housebuilders were also interested, not least because of the implications of a high performance window. ‘It means they can downgrade other components and save money’, he added.

It is already apparent that most framing systems can achieve a ‘C’ rating. Martin Althorpe, Technical Director of Spectus Window Systems:

‘Our in-house research team has been analysing all our window products over the last few months and it may be possible to achieve anything up to an A rating using existing components.

‘However, it is most unlikely that this performance would ever be required in normal circumstances and more significant is the fact that our standard window system will give a ‘D’ rating (i.e. is acceptable in most refurbishment situations). Careful selection of the components available will enable a ‘C’ or ‘B’ rating to be achieved.’

Sapa offers a view from the aluminium systems side:

‘The framing material actually makes little difference. Our products easily meet the requirements of this round of changes to Part L and we do not believe this will have a detrimental effect on our customers’ ability to sell aluminium as a product.’

A new type of unit

While WERs is unlikely to prompt a change in window systems, a new type of sealed unit has already emerged. It features an outer pane of low iron glass, which has a lighter shade and allows more solar gain. Apparently all the major glass manufacturers have a low iron option that is readily available. Gas filling units further improves insulation with no detriment to solar gain.

Cost and pricing

We turn to Masterframe for some reassurance of the premium on rated windows: Technical Manager Ray Rabbett calculates the cost of upgrading to a ‘C’ rating on the Bygone Collection to be just an extra three per cent. The energy saved pays for this in under two years. The estimate covers the costs of testing. Preferred installers are about to be offered a free upgrade for two months.

‘A’ rated windows will undoubtedly appeal to some customers and there is some hope that the cost won’t be much different: As we went to press, a double glazed window with Saint Gobain glass was under examination, and was expected to achieve an ‘A’ rating.

Too early to call

It’s too early to assess the impact of Window Energy Ratings, save to say it will appeal to a wide range of customers, including homeowners and local authority specifiers. We will be featuring this topic again in July, with updates in the meantime.