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Building Products January 2018

DOORS, WINDOWS AND ACCESSORIES grown too, opening up space in the market for niche products. The problem with using aluminium through the building envelope is that it’s a highly conductive material – creating spaces which are prone to being too hot or too cold. PVC-U has experienced many years of success, not only because it’s cheaper to manufacture, but also because it has gone through a period of quite intense scrutiny when it comes to thermal efficiency. Building regulations for replacement PVC-U windows and doors are relatively strict and systems companies competitively market their PVC-U products with A+ energy ratings and below 1.0W/m²K Uvalues. In contrast, if you look at the advertising strategies for aluminium suppliers, they tend to focus much more on slimmer sightlines, structural rigidity and ‘Grand Designs’ style aesthetics. So, in order to combat the poor thermal performance in aluminium, product designers need to use a form of thermal break. As PVC-U is so thermally effective, it makes the most sense to use a multi-chambered PVC-U core as a full width thermal break – and it enables the finished products to achieve U-values comparable with some of the best PVC-U profiles available, with the advantage of an aluminium finish. While thermal performance is typically the main driver in the development of warm aluminium products, you also benefit from easier installation and lower material cost than pure aluminium and gain the advantage of faster turnarounds for dual colour specifications. There really are very few downsides to working with a warm aluminium product – particularly if 30 BUILDING PRODUCTS | JANUARY 2018 you are used to working with PVC-U. For installers and builders, the PVC-U core in a warm aluminium system makes installation very simple because along the jambs where fixings are applied, the material is the same. We just recommend that installers take extra care to ensure bowing doesn’t occur from overtightening fixings; the aluminium exterior won’t have as much flex as a solely PVC-U product – although in bi-fold, French and patio doors, we see this as an advantage, because the door is less likely to bend or warp during use. Additional security Aluminium is intrinsically stronger and more rigid than PVC-U products, so the exterior on warm aluminium products provides additional security. While burglary figures have reportedly hit an alltime low in England and Wales, there have been a number of cases in the last couple of years where burglars have used blow torches to melt the PVC-U around door handles as a way of gaining entry into homes, with attempts in Leeds and Stockport attracting local press attention. As burglary attempts become more sophisticated – even if fewer are happening – there is a need for the industry to find better materials and solutions to protect residential properties and warm aluminium may be one answer to that. Perhaps the biggest impact that warm aluminium products have had on the supply chain though, is the faster lead times generated through the benefits of the composite structure. This means dual colour can be achieved at the point of manufacture, without the need for an off-site operation, which can add many weeks to product turnaround. <<< Continued from page 29 Anthracite grey, or black with a white interior, is so common with consumers now, the supply chain needs to be able to respond to this demand on the same lead times as single colour specifications. While we’re on the subject of colour, warm aluminium products are usually finished with powder coating which maintains its colour integrity for longer than PVC-U products, which do still face some discolourment as they naturally age. Most suppliers still only offer a 10 year standard guarantee on aluminium/hybrid products, but the Qualicoat powder coating guarantee is actually 25 years, with a Coastal Class rating of 5 guaranteeing 10 years in coastal and industrial areas. As we are moving from the second generation of replacement double glazed windows onto the third, advantages like this will really begin to stand out, for all concerned along the supply chain. While currently a relatively niche area of the market, the incorporation of warm aluminium is a very future-proof approach to designing new homes and is also proving to be well received in retrofit applications, so we see a very bright future for this product range. www.warmcore.co.uk


Building Products January 2018
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