Embodied Carbon
All activities that are responsible for producing carbon dioxide can be said to have a carbon footprint. In the UK, on the 26th November 2008, the government passed the Climate Change Act into law which for the first time has set legally binding targets on the UK to reduce carbon emissions by 80% by 2050 with various interim targets to be achieved, e.g. 34% reduction over 1990 levels by 2020.
The UK government is now putting pressure on the buildings and construction industry principally by tightening the requirements in Part L of the Building Regulations to improve energy efficiency and through a new building code called the Code for Sustainable Homes, which applies to new housing only.
Therefore most focus in the construction industry has been on reducing the energy actually used in buildings rather than on reducing the energy used, and resulting carbon emissions, in manufacturing the building materials themselves (their embodied energy). This emphasis is likely to change as by 2016 with tightening regulations for efficiency of energy-in-use most new homes will be "zero carbon" or carbon neutral in terms of their energy-in-use. This means that the embodied energy (carbon) footprint of buildings will become increasingly more significant. In response to this Redland commissioned engineering consultants Ove Arup & Partners Ltd to undertake embodied energy and carbon analyses of our manufacturing operations to understand first the carbon footprints of Redland products and develop strategies for their reduction.
Ove Arup & Partners (www.arup.com) is a prestigious international and independent firm of designers, planners, engineers, consultants and technical specialists offering a broad range of professional services. Founded in 1946, they designed the Sydney Opera House in Australia and the Pompidou Centre in Paris, and more recently the spectacular "Water Cube" aquatics centre for the 2008 Beijing Olympics. In recent years they have specialised in sustainability and energy, working on various projects, from designing Proctor & Gamble's sustainable design guidelines, to master planning for Northstowe, a 9,500 homes sustainable new town north of Cambridge.
The study was reviewed independently by the Carbon Trust, and also by Professor Geoff Hammond, one of the UK's leading experts on carbon footprinting and also Director of Sustainable Energy at the University of Bath. Both reviewers confirmed the Ove Arup study was of high quality and in line with the requirements of PAS 2050 and ISO 14040 Life Cycle Assessment (LCA) standards.
PAS 2050: Specification for the assessment of the life cycle greenhouse gas emissions of goods and services, is a new method that has been developed by the BSI, the Carbon Trust and Defra (Department for Environment, Food and Rural Affairs) specifically for calculating the embodied carbon of products and services. It is rapidly becoming the accepted UK standard method for calculating carbon footprints and is internationally accepted across Europe, North America and most of the developed world. It is also the method that has to be used if companies want to put the popular carbon footprint label developed by the Carbon Trust on their products and services in the UK. The Ove Arup report calculations conform to PAS 2050.
In the late 1990's, Redland published a report by a building design practice called b consultants, entitled "A Guide to Sustainable Roofing". The report compared the embodied energy of clay tiles, concrete tiles, natural slate, coated steel sheet, aluminium, copper, lead, flat roofing, shingles and thatched roofs. In this report, concrete tiles at 40-90 MJ/m2 were shown to have a much lower embodied energy than clay tiles at 270-340 MJ/m2. Interestingly, the figures in the Ove Arup report, based upon 2007 data, show the embodied energy for concrete tiles at 91-146 MJ/m2 and clay tiles at 240-478 MJ/m2 respectively, which is quite consistent with the report from the late 1990's.
It is a common perception that natural materials like clay and natural slate are more environmentally friendly than concrete. What often is not appreciated is that energy is required to turn natural materials into finished products. While the energy used to make natural slates at 130-160 MJ/m2 is similarly low to concrete tiles because both manufacturing processes are low temperature, clay tiles have a much higher embodied energy due to the fact that to achieve the necessary strength they must be fired at around 1000°C in a kiln, normally gas fired. In contrast, just adding water and curing at less than 100°C can achieve the necessary strength for concrete tiles.
If you would like more information on the Ove Arup report, a Questions and Answers sheet is available to download here