Setting Standards in Durability & Sustainability

For the second year running, the Wood Window Alliance announced the results of groundbreaking new research at Ecobuild in its burgeoning campaign to promote the high performance and durability of 21st century wood windows.

INDEPENDENT RESEARCH remains a cornerstone of the Wood Window Alliance campaign. Architects and specifiers require proven scientific data to support the case for the products and materials they choose and only independent and authoritative research will provide that information in a way that reflects the requirements of increasingly demanding legislation and standards.

This year’s research builds on previous Life Cycle Assessment research by Imperial College for Akzo Nobel in 2004. The Akzo Nobel research showed that timber windows made to TWA (Timber Window Accreditation) Scheme standards gave a 40-year service life. Six years on, the new study by Imperial College used ISO 15686-8:2009 methodology to assess and quantify the impact of the major advances in design, manufacturing and coatings technology incorporated in today’s Wood Window Alliance windows. The research found that windows manufactured to WWA standards give a service life of 60 years1. That figure is important, particularly for specifiers and architects working on local authority and public buildings, because it reflects exactly the design life specification required for new buildings – 60 years.

And the new service life story does not end there – enhanced maintenance regimes and sheltered conditions can extend that service life to 80 years and even beyond. For Richard Murphy of Imperial College, who undertook the new study, the research implies that there is no
reason why today’s Wood Window Alliance windows should not last a lifetime, in the same way that Victorian and Edwardian wood windows are still to be seen in buildings around the country.

There is no doubt that this latest research validates the huge advance in manufacturing standards over the last five years or so. It can now be said that Wood Window Alliance windows will actually last the design life of a building and this is great news for any specifier or consumer who can buy WWA windows with the confidence of knowing that they will last a lifetime.

The new Imperial College data was also used to provide a new Whole Life Costing analysis. The work considered building life periods of 60, 80 and 100 years across a range of exposure conditions and maintenance regimes for two WWA Alliance A and C energy rated windows and comparable PVC-U windows. As the graph shows, the results proved that the extended life of a WWA window results in lower Whole Life Costs than the PVC-U windows at 60 years and beyond, giving cost savings of between 2% and 7%.

All this builds on the first piece of major research announced by the Wood Window Alliance last year. This showed that WWA windows are carbon-negative2 and was the first study to measure the embodied energy of wood empirically. Davis Langdon measured the embodied energy of a selection of WWA standard A and C rated windows over 30, 60 and 100 year service lives and the results showed that, despite carbon emissions from transport, production, maintenance and end of life, Wood Window Alliance frames are still carbon negative because of the carbon sink effect of sustainably managed forests. All Alliance windows must be sourced
from sustainably managed forests where new growth exceeds harvest.

That means the WWA can legitimately claim that every Wood Window Alliance window specified instead of a PVC-U window saves around 89kg of CO2e over the life of the window. For a typical house, that’s around three quarters of a tonne of CO2e, the equivalent of driving almost 5,000km in a typical family car3. To put this in perspective, if just half the PVC-U windows fitted in the UK in 2008 had been Alliance windows there would have been a saving of over 300,000 tonnes of CO2e.

Put all of this data together and there is a strong case for Wood Window Alliance windows. New messages about Service Life, Whole Life Costing, Life Cycle Assessment and embodied energy provide the bedrock of the WWA campaign as each is supported by independent research, carried out by experts in their fields. After three years of campaigning, the Wood Window Alliance has made huge steps forward in building a solid, scientific case for modern wood windows in a world where the use of truly sustainable materials has become an imperative.