Spent the morning sitting in on a conference at Bath University on carbon footprinting. God, is it complicated! Not only is the available data very patchy, but there seem to be countless ways of accounting for it. By way of example:
• You have a choice of whether to count embodied energy, or carbon dioxide or all greenhouse gases (known as CO2e for CO2 equivalent). Each gives a slightly different result
• You can measure direct emissions (Scope 1), adjust for different emissions from electricity production (Scope 2), or count all the different emissions from pre-production work or imports (Scope 3)
• Products can be assessed cradle-to-factory gate, or cradle-to-site or cradle-to-grave (which includes their ultimate disposal)
• You can choose to include or exclude a) feedstock energy, which is the energy embedded in plastics which might otherwise have been burned as oil and/or b) sequestered energy, which is energy locked into timber or plant matter which might have rotted or burnt if it hadn’t been used in a building.
And this just covers the built environment. Leave that behind, and you move into the realm of ecological footprinting where everyone starts to talk in units of global hectares, which leads to the One Planet Living concepts. I came away with the impression that there an awful lot of academics out there beavering away at ever more complex algorithms, and that the rest of the world knows very little about any of it.
The star of the show for me was Craig Jones, who works at Bath’s Sustainable Energy Research Unit. He is the man behind the Inventory of Carbon & Energy or ICE database, which is the only place I know of where you can look up embodied energy data on building materials, without having to pay for it. Craig is involved in analysing published data from a variety of sources around the world and trying to make sense of it for the UK market, and he and his boss Professor Geoff Hammond have decided to make the fruits of their research available online as a public resource. Consequently, it gets very widely referred to by sustainability consultants and used as the basis for a lot of buying decisions. In fact, one delegate told us that every single water company in the land now refers to ICE when specifying their future investment programmes.
Craig gave a twenty-minute presentation, which included a summary of his methodology. Which, if my notes serve me correctly, is:
• CO2, not CO2e (it’s not usually that different)
• Cradle to Gate. He ignores transport costs, but reckons they rarely amount to more than 5% to 8% extra
• Feedstock energy gets included
• Sequestered energy in timber gets excluded
His logic for excluding sequestered CO2 wasn’t entirely convincing. What he said was that whilst it was true that using timber in buildings did effectively lock away carbon dioxide for the duration of the building’s life, he felt that there were still many unresolved issues with what happens to the large amounts of timber waste which doesn’t get used on site. He was happy to accept that it’s a contentious area. He did however admit that much of the timber data is sketchy and he relied on work done in North America, which puts the embodied energy of timber at a surprisingly high figure, mostly to do with the energy involved in kiln drying. I’ve read some of this stuff and have to say it gets bogged down on whether the kiln drying process uses fossil fuels or waste wood chips at the sawmill. Some sawmills do one thing, others do something else. You can see how this stuff ends up going around in circles.
Despite all the problems, Craig (the IceMan) is now becoming identified as the UK’s repository of information on embodied energy, and all because he’s gone open source. A lesson here for others. He’s obviously put a huge amount of work into compiling the database and should be congratulated for creating so valuable a resource. What needs to be done now is some comparative studies of different construction methods using the ICE data as a reference.
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