Technical Feature
Setting the sustainable standard
Stuart Crisp, Business Development Director at the Concrete Pipeline Systems Association (CPSA) explains how the use of appropriate accounting methods for calculating the carbon footprints of drainage installations can have an impact on selection of pipeline material.
There are numerous factors that impact on the environmental impact of a drainage installation. One of the most common is the contribution to a scheme’s carbon footprint made by the materials used in its construction.
Manufacturers have, of course, realised this and there are a plethora of competing claims for the sustainability of different materials. The challenge for specifiers is in ensuring the validity of these claims.
Take for example the issue of concrete and plastic pipelines. The concrete pipeline industry published a report in 2010 based on a detailed study of the embodied carbon for precast concrete pipes, manhole rings and cover slabs. This study was used to produce a report providing a comparison between concrete pipes and plastic pipes. This study indicated that concrete pipes have up to 35% lower cradle-to- site embodied carbon when compared with HDPE pipe using the same full granular (Class S) bedding design.
The plastic pipe industry responded. A manufacturer used the concrete pipe embodied carbon values from the CPSA study and compared them with an alternative set of values for plastic pipes, which were based on a much older generic study, as opposed to one based specifically on the manufacturer’s own plastic pipe products. Unsurprisingly, this study
indicated a lower carbon footprint for plastic pipes.
What this snapshot shows is that different accounting methods and sources of data can lead to different results. This is important for specifiers looking to make a considered choice between concrete and plastic pipes. When making a comparison it is worth bearing in mind:
Most plastic pipe manufacturers currently use HDPE pipe carbon footprint data based on an Eco-profile study carried out by PlasticsEurope (a trade body for plastics resin suppliers) in 2005, which was republished in 2008 with amendments. It is, however, a moot point as to whether the carbon footprint produced by that study is based on a recognised methodology and contemporary data.
The PlasticsEurope Eco-profile study was originally developed using framework standard ISO 14040/14044 Environmental Management: Life Cycle Assessment. Framework standards allow for a wide range of methods and boundaries and would not give a steady set of rules to enable a consistent methodology. By contrast, the use of a recognised methodology such as EN15804 Sustainability of construction works. Environmental product declarations. Core rules for the product category of construction products does allow for fair comparisons between different materials. An Environmental Product Declaration (EPD) is an ISO standardised and LCA based tool to communicate the environmental performance of a product or system.
The CPSA considers that the methodology used for the Eco-profile study would not be acceptable under the EN15804 methodology required for construction product Environmental Product Declarations for a number of reasons:
• Some of the data used is
out-of-date.Based on a study by IHS, the Plastics Europe database was developed from a lifecycle exercise carried out in the 1990s; since then CEN/ASTM and ISO standards for plastic pipe and resins have changed.
• The data used assumes resin suppliers are 100km away. The CPSA suspect that resins for UK plastic pipe manufacture are sourced from both inside and outside the EU. A study by sustainability organisation Carbon Clear showed that using resins sourced from outside Europe could increase the carbon footprint of an average HDPE pipe by over 30%, based on ‘local’ energy conversion factors, even before transport emissions are included.
14 drain TRADER | December 2016 |
www.draintraderltd.com
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