The arguments in favour of sustainability and legacy in construction are understood by a growing number of designers, builders and joinery manufacturers, but there are still challenges ahead. Less readily available to back up the message are the facts that explain the benefits of sustainability in a readily digestible way. Everything we do leaves behind an environmental footprint but how do you quantify that in a clear, concise and usable way? Data are needed that equate the use of a product with its effect on our planet, and offer meaningful comparisons between alternative materials such as timber and PVCu.

As part of its contribution to this area, Akzo Nobel Specialist Coatings commissioned experts at Imperial College London to provide these data by studying the sustainability credentials of Sikkens factory-applied finishes and brush-applied maintenance systems.

For several years Sikkens has led the way in life cycle assessment (LCA) of these coating systems and continues to update and refine the information as market needs change. The latest report has provided the most comprehensive LCA available of such a coating system. It will become a valuable tool in supporting the joinery industry in its efforts to improve environmental performance and demonstrate best practice. It will also enable specifiers to make informed decisions about the use of timber windows and doors instead of PVCu to achieve the optimum environmental and economic solution.

Dr Bill Hillier and Dr Richard Murphy of Imperial College have produced a life cycle assessment for Sikkens factory-applied coatings and brush-applied maintenance systems which provides reliable measures of sustainability and an efficient means to put information in front of consumers. The work, which is in accordance with ISO 14040 international standards, has provided independently verified ‘cradle to grave’ information relating to the full service life of a typical UK timber window. The findings, which are based on 10m2 of component surface, took as their starting point the highest possible levels of design and performance and the research looks at an extended life cycle of 40 years.

Market trends

The window system studied was considered as typical of the market sector for the coatings systems analysed, as was the choice of a water-borne timber preservative. The research was concerned to encompass both current and future market trends. For comparison, the study also looked at the sustainability credentials of a PVCu window and of a timber window treated with both a solvent-borne translucent and opaque coating systems.

It is worth noting that all previous LCA studies of coatings have omitted some of the minor components in the formulation of the product systems. There are no such omissions in this study which encompasses all facets of the coating system in order to fulfil Sikkens’ desire to trace the product from concept to end of life.

Also, while an extended lifespan was selected, an additional scenario of 100 years was added to allow for the fact that large numbers of timber windows from the Georgian and Victorian eras are still in service. Climate is also a crucial consideration, so northern coastal and southern inland locations were used. Each was divided into exposed south and sheltered north facing.

Disposal

End of life disposal options were also factored in, assuming that some material will be incinerated and some landfilled, but recognised the changing balance of methods of disposal in line with European directives. The results underline the advantages that timber has over PVCu in the disposal categories.

A dozen environmental impacts were computed for the assessment. The ones of headline concern are the effect on global warming; ozone depletion; fossil fuel consumption and hazardous waste production. The impacts, in short, all relate to the environmental footprint. The resulting figures are expressed as a percentage, with a score of 100 being the amount of fossil fuel consumed in total by one UK citizen in one year. Thus, for example, the LCA report concludes that the Sikkens 40-year life of its coatings system only amounts to 0.180% of the impact made by the average UK citizen under the heading of global warming.

The table reproduced below gives straight comparisons between the Sikkens water-borne coating system, PVCu and a solvent-borne alternative on timber. As will be seen, the environmental impact of the water-borne coating system is less throughout its life than both alternatives with end-of-life scores (expressed in terms of waste produced) going off the scale as far as PVCu is concerned. The same is true in the case of timber versus PVCu on the 100-year cycle, assuming in both instances that the windows have been replaced once.

For a report summary visit www.sikkens.co.uk