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| BUILDING REGS |
| Recent changes to the Building Regulations affect not only people building their own homes from scratch, but also those planning to add to or extend their existing homes. The changes to regulations are far-reaching, but nowhere is the impact more keenly felt than in the aspect of fenestration, where Part L requirements introduced as a result of the Kyoto Conference affect the design of both the frame and the glass that it accommodates. Self-builders who fall foul of the regulations may find themselves in serious trouble, and subsequently find selling on their new or extended home difficult in the future. Kyoto commotted the industrialised nations to reducing the emissions of six damaging gases significantly by the year 2010. CO2 emissions in the UK were to be reduced to 20% below their 1990 levels.How does this affect house-builders and homeowners? Well, whilst 19% of the UK's CO2 emissions result from non-domestic buildings and associated building services, a massive 27% of the UK emissions are caused by the energy consumption of domestic dwellings. To address the issue is not only sensible for the planet, but is also a wise move for the financial well-being of the individual home-owners concerned. The new Part L regulations for England and Wales, and their equivalent in Scotland - Part J - came into force in April of this year. For those involved in home refurbishment, projects need to comply with the new requirements now, unless planning approval for the project was granted prior to April 2002. Part L requires that each element of the building fabric must achieve within a maximum U-value. For metal windows, doors and roof windows, the requirement is 2.2W/m2K; for timber and PVC windows the figure is 2.0/m2K. |
| With all the advances in window design and technology, particularly in the PVC sector, it would be reasonable to expect that all modern windows would easily comply with the requirements. In fact, the contrary is very much the case, and many standard double glazed windows currently on sale for the newbuild and refurbishment sector fail to meet the new regulations. Assuming that your local double-glazing man has got the matter in hand could be a dangerous mistake. So what do you need to know to be able to choose the right window? Well to start with, window manufacturers must be able to provide certified U values for their products as proof of their performance. The industry, with the backing of the government which is keen to see the back of cowboys in the windows market, has its own self-regulation scheme, called FENSA. Window fabricators, or the systems supplier they use, should have subjected standard windows to regulated hot-box testing to BSEN ISO 12567 - 12000, and then checked by calculation other window styles in their range. |
It sounds easy then. The problem is, that in striving to get the windows to comply with the Part L requirements, the fabricator may have to compromise on other elements of the window's performance. For example, PVC windows with no metal reinforcing are likely to achieve better U values than those with reinforcing. The difference can be as great as 8%. But an unreinforced window is unlikely to have the required structural strength. Other things affect thermal performance too. Whether the frame has two, three or four chambers will affect the thermal effectiveness of the window. Four chambers is best. The type of glass, the size of the gap between the panes, and what gas is used to fill it, all play a major part. ARgon-filled units out-perform airfilled units; some units struggle to comply whatever gas fills them. Surprisingly, there is little difference in performance between 24mm and 28mm units, but 28mm units offer much better acoustic performance - an important factor for those close to major roads or rail lines.
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| Glass manufacturers have created a new soft-coat low E glass which gives excellent thermal performance but is both expensive and difficult to work with, reducing its appeal for windowmakers. In fact, Sheerframe four chambered 6000 and 7000 frames, with argon filled Pilkington Therm 24mm glazing units using hard-coat K glass, have achieved some of the highest performance standards of any doubleglazed windows currently tests. A new concept in reinforcing - Thermlock® - gives even better thermal performance of Sheerframe windows, whilst still retaining the product's structural integrity. With plans in Scotland already afoot to tighten the performance requirement to 1.8W/m2K next year, and England and Wales likely to follow suit in the near future, it looks likely that the Thermlock®/Sheerframe® combination will be the one that others try to emulate. |
| Seeking out a good specialist subcontractor, registered with the regulatory body, FENSA, is a good place to start in ensuring that you meet Part L requirements with regard to window performance. Do not be afraid to ask tough questions of the suppliers you approach. But remember too, that other regulations apply to window design and choice too. Under Part B of the building regulations, many windows now also have to provide the facility for egress; you will want your windows not only to provide the light and ventilation you require, but also to be fitted with the kind of efficient hardware which is both long-lasting and delivers the levels of security you demand. Reducing maintenance costs is a key factor in specifying any component for a building, and PVC with well-chosen hardware, plays a major role here. Finally, remember that windows perform a function - and they have regulations with which they have to comply - but they are also a fashion item, and you need to ensure that the style you choose suits you. Advances in PVC window design mean that you need make no compromise on performance when choosing the style you require. |
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