Embedding low carbon design?
A dedicated carbon manager helps to integrates low carbon into the design of a building by becoming involved at every stage of the process – working alongside the architects, designers, structural engineers, and building services engineers. Their role is to interact with the design team, giving advice on low energy buildings and low embodied carbon buildings. Throughout the process they will try to identify reductions. Source: Guy Battle, partner, dcarbon8 (Deloitte)
Project stage
Interactive process
Planning
Concept & scheme
Interactive process
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500 and 7,500 kWh per sq m. Moncaster insists: ‘I think that, in order to reduce emissions from housing, we need to be able to measure all the emissions, and not ignore those due to the embodied energy just because they’re complicated.’ Apart from the fact that industry is only now
Detailed design
Feedback loop
Tender
Interactive process
Construction
Use & end of life
Interactive process
Interactive process
Interactive process
beginning to grapple with the concept, another rather concerning point is the ‘massive lack of awareness’ in the supply chain. Battle says: ‘They’ve [manufacturers] generally got no idea – they run away like headless chickens when you put it in a specification.’ He also criticises manufacturers for charging a cost
premium of 10, 15 or 20% for low carbon products: ‘In theory, when you have a lower carbon material it should use less energy; by definition it should cost less.’ But he describes it as ‘fundamental’ that embodied
carbon be included within Building Regulations, and says planning authorities should adopt embodied carbon as a measure, putting less emphasis on
Ropemaker Place Calculating an office’s lifecycle carbon footprint
British Land’s commercial city office building, Ropemaker Place, London, has had its ‘lifecycle carbon footprint’ calculated. The developer asked carbon and sustainability consultancy dcarbon8 to measure and calculate the amount of embodied and operational carbon that will be used throughout the Ropemaker’s lifecycle – expected to be 60 years. A leading engineering consultancy
carried out two calculations of energy use for the building: the first using SBEM, and the second using a more complex dynamic model based on different assumptions of occupancy and ‘small’ power. Ropemaker’s energy use was found
to be as much as 53% higher than that calculated in SBEM for the purposes of Part L compliance (see chart, top right). Dcarbon8 used its own in-house tool to
calculate the embodied carbon. This took into consideration the carbon impact of all the lifecycle stages, primarily: the carbon generated by extracting the raw materials; the transportation of those materials to site; the on-site activities during construction; the maintenance of the building, such as replacing the cladding; and how the materials used in the building are disposed of at the end of its life through dismantling. This information gave the 20-storey,
595,000 sq ft office block, over a 60-year lifespan, a total carbon footprint of 197,000 tCO2e – equivalent to 98 years’ worth of the building’s energy consumption. The split between embodied and operational
carbon is 42:58. But, according to Guy Battle, partner at dcarbon8, if the grid is decarbonised from 0.5 kgCO2e/kWh in 2010 to 0.1 kgCO2e/kWh in 2030 and 0.2 kgCO2e/kWh in 2050 (as cited by the Committee on Climate Change in 2008), the split between embodied and operational carbon changes to 68:32. Sarah Cary, sustainable developments
executive at British Land, says the research has led to a number of lessons learned about the way it builds and maintains property. For example, the research has enabled British Land to calculate its total
development carbon footprint for 2008 and 2009 – see chart, bottom right – using the results from Ropemaker Place as a baseline. This analysis has also shown that
some 50% of its total carbon footprint is controlled by its own activities and decisions as a developer and owner, with the other 50% the result of the activities and decisions of its occupiers. It also revealed that extraction, fabrication and erection of steel and concrete comprised an estimated 16% of the total carbon footprint at Ropemaker, making them priority materials for British Land to focus on in future developments. Maintenance and refurbishment was also found to account for 15% of the total footprint over a 60-year lifespan, indicating that British Land should also focus on refurbishment specifications in the future. The research also suggests that, if the
national electricity grid decarbonises, as planned by government, Ropemaker Place’s total carbon footprint would decrease by 39%, resulting in the proportion related to materials and site construction activities (embodied impacts) increasing from 42% to 68%, meaning the developer’s choice of building materials in the future will be even more important. Cary concludes: ‘We need to pay attention
to what we’re doing now with our fit-outs and refurbishment. Embodied carbon is bigger than we thought it was. We didn’t realise it was such a big factor in our impact on the environment.’
32
CIBSE Journal July 2010
www.cibsejournal.com
Land Securities
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