The wood industry has changed significantly over recent years. There was a time, not that long ago, when the industry supplied not windows, but primed frames to be glazed and painted on site. The focus was on cheap timber, which needed regular sanding and recoating to avoid premature rot. How times have changed. Over the last 10 years or so, there has been a revolution in the way we make high-performance wood windows in the UK, from the use of engineered slow-growth substrates, to full factory finishing with advanced coating systems and double- or triple-glazing. Today’s factory-finished wood windows deliver unbeatable energy performance, exceptional durability and minimal maintenance – all with a much lower impact on the environment than PVC-u.
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Of course, whether planning new or refurbishment projects, social landlords are looking hard at all costs, including the cost of maintenance regimes. So, seeing PVC-u windows are cheaper to install than wood, and making an assumption about maintenance costs, they could be forgiven for believing PVC-u offers better long-term value.
A study1 by Heriot-Watt University shows that wood actually provides better value than PVC-u in the long-term, thanks to the wood frame’s longer life and extended maintenance cycle.
The study shows that factory-finished wood window frames made to WWA standards have roughly twice the planned service life of equivalent PVC-u frames – 56 to 65 years for wood against 25 to 35 years for PVC-u.
All windows, whatever the material, need regular maintenance. The difference between wood and PVC-u is that the wood coating needs to be refreshed periodically, whereas PVC-u windows will tend to age and discolour until they are replaced. Anyone used to the sort of re-painting regimes associated with traditional wood windows will be in for a surprise. The typical recoating cycle on a pale opaque finish is eight to 10 years – with minimal preparation and just one or two topcoats to restore the window to pristine condition.
The study shows the wood frame to have significantly lower lifecycle impacts than an equivalent PVC-u frame, particularly when it comes to Global Warming Potential, when the wood frame saves 160kgs CO2e when used instead of the PVC-u frame. In an average property, you can save at least five tonnes of CO2e just by choosing wood windows and doors instead of PVC-u.
It’s worth taking a moment to summarise some of the specific benefits of specifying WWA wood windows:
• They can be every bit as energy-efficient as PVC-u
• They are available in a wide range of RAL colours and stains (including duo-colour – different colours inside and out)
• They will be a better long-term investment than PVC-u
• They offer tilt-turn for easy cleaning or decorating – and tilt-slide for vertical sliding sashes
• They comply with Part Q (security) and can be manufactured to the Secured by Design standard
• Buying from a member of the WWA gives you the reassurance that the windows and doors meet rigorous quality, performance and sustainability standards, backed up by third-party certification and industry-leading warranties.
Corporate social responsibility
But what about your CSR as social landlords? Do you need to think about the wider impacts of the materials specified in your buildings? If you buy wood products with Chain of Custody certification, you know the material they are made from is natural, renewable, biodegradable and beautiful. What about PVC-u?
PVC-u production is energy-intensive. Chlorine, a major constituent of PVC, is energy- and emissions-intensive. 8.06 million tonnes of chlorine – roughly a third of Europe’s total chlorine production – was used to manufacture PVC in Europe alone in 20132.
PVC-u production is potentially toxic. PVC is made from vinyl chloride monomer (VCM), a Class 1 human carcinogen3.
Many companies and organisations have placed PVC on a banned or precautionary list, including, for example, the Cradle to Cradle Product Innovation Institute, the US Green Building Council, Perkins+Will architects, Google, Nike, Volvo and Apple4. Little PVC-u is recycled. PVC-u is typically downcycled, not recycled. And, sadly, relatively little is recovered – according to Waste Management World – in 2013; only some 15% of old PVC-u windows were recycled in the UK5. But recycled PVC-u is a major pathway for hazardous legacy materials, such as mercury, cadmium and lead, into new PVC-u products.
We understand that the pressure of costs will mean many social landlords will turn first to PVC-u for windows and doors, but we believe the case for wood has never been stronger – both in terms of long-term value and in terms of the effect of PVC-u on the planet.
1. Dr Gillian F. Menzies, Institute for Building and Urban Design, Heriot-Watt University, June 2013, Whole Life Analysis of timber, modified timber and aluminium-clad timber windows: Service Life Planning, Whole Life Costing and Life Cycle Assessment
2. The Alliance for Sustainable Building Products, February 2017, uPVC windows through the lifecycle
3. Janet Kielhorn et al, ‘Vinyl Chloride: Still a Cause for Concern’, Environmental Health Perspectives 108, no. 7 (2000): 580
4. www.chej.org/pvcfactsheets/PVC_Policies_Around_The_World.html and http://www.c2ccertified.org/resources/detail/cradle-to-cradle-certified-banned-list-of-chemicals
5. Waste Management World, 31st January 2013