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Features
Concrete evidence for carbon footprinting Stuart Crisp argues for a consistent method of carbon footprinting the concrete pipes used by water companies. Government targets are behind a relentless drive to evaluate and reduce the carbon emissions of all aspects of UK construction. Water companies have a very specific brief to monitor, measure and mitigate the environmental impact of their work. There are, of course, a number of factors to take into account, but the contribution that materials make to the whole is an important one. Manufacturers have realised this and there are a plethora of competing claims for the sustainability of different materials. What is lacking, however, is a widely recognised and consistent method for evaluating these claims. The Concrete Pipeline Systems Association (CPSA) has responded to this by investing in independently certified research, using a recognised methodology, to assess the carbon footprint of concrete pipelines. It is hoping to establish an industry-wide understanding of carbon accounting processes that can be used to reliably compare different products and activities. So what is meant by the term carbon footprint? The fundamental misconception is that the term relates only to the carbon dioxide emitted during a manufacturing process. In fact, it is a measure of the impact of all greenhouse gases and is expressed as carbon dioxide equivalent. Methane, for example, is currently regarded by the Intergovernmental Panel on Climate Change as 25 times more damaging than carbon dioxide. One kilogram of methane is therefore reported as 25kg of carbon dioxide equivalent. This fact is highly significant because many of the standard databases used to rate different construction materials are based on carbon dioxide-only figures. Which brings us to the question of how to establish the environmental impact of different materials. Which claims can be supported? If you are putting together a carbon footprint report or using data supplied by others, it may be worth using this simple checklist. Ensure the carbon footprint data: * has been developed using a recognised methodology such as ISO 14044/14040 or the just revised PAS 2050; * is validated by an independent and recognised specialist; * is clearly defined as carbon dioxide or carbon dioxide equivalent; * specifies the boundary conditions (what is included and excluded in the scope of the study), source data and assumptions that have been applied and is based on representative data in terms of time, geography and technology coverage. As the industry body representing the manufacturers of pre-cast concrete pipelines, the CPSA has undertaken the task of producing detailed reports on behalf of the sector. We set up a research programme with the help of consultancy Carbon Clear to look at the carbon footprint of our products and how they compare to other types of pipeline products and construction methods. The result is a set of three reports covering: the carbon footprint of our products; how concrete pipes compare with plastic pipes; and a comparison between circular precast concrete manhole systems and other solutions. The cradle-to-gate carbon footprint of concrete pipes ranges from 16.36kg to 559kg carbon dioxide equivalent per metre (CO2e/metre) for pipes of nominal diameters between 225mm and 2100mm (DN225 up to DN2100). This is 20-60 per cent lower than the values for generic precast concrete derived from many industry databases. The cradle-to-site greenhouse gas emissions of concrete pipes were found to be generally better than plastic pipes and up to 35 per cent lower carbon dioxide equivalent for DN2100 pipes. The reports also demonstrate that DN1200 circular precast manhole systems have 30 to 43 per cent lower carbon footprints compared with DN1200 traditional manholes, 1250 x 1250mm box-based manholes and DN1050 plastic manholes. Manufactured product only provides one element of an environmental impact assessment of any project. Transportation, installation, water usage, waste disposal and so on all need to be factored in, but it would be a good starting point if there were reliable and generally recognised figures available for different materials. We hope that we have taken a good step in this direction. Stuart Crisp, business development director of the Concrete Pipeline Systems Association. Source: Utility Week © Faversham House Group Ltd 2011. News articles may be copied or forwarded
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