Dr Craig Jones of Sustain argues addressing embodied carbon is as important as cutting operational emissions
It has been a long and painful process to get the importance of embodied carbon onto the government's agenda. The publication of the Low Carbon Action Plan this year marked a milestone in this process.
This matters because embodied carbon has, for so long, been the poor relation when it comes to carbon footprinting buildings - out of sight and, consequently, out of mind.
A new report from Low Carbon Workplace suggests that embodied carbon represents a very small percentage of the operational carbon of office buildings.
However, the data used to build the above analysis is simply wrong. It compares the embodied carbon in the construction of a new building with the operational carbon of old and inefficient office buildings. Embodied carbon becomes important when constructing a new building and in refurbishing existing buildings. There, comparing the operational carbon of existing buildings with the embodied carbon of its past construction is unfair, and inaccurate.
For a new office building, the operational carbon is roughly half the value of this analysis. If we use data which compares like with like, the embodied carbon value jumps from the 10 to 15 per cent outlined in the Low Carbon Workplace report to 20 to 30 per cent. This is obviously significant - embodied carbon can represent up to a third of the whole life carbon of a building.
The issue here relates to the figure used to calculate an embodied carbon footprint - 150kgCO2 per square metre per year. This is old data, collected in the mid-1990s and reflecting office buildings at the time, not modern buildings. Newer data, supported by CIBSE and RIBA, suggests a figure of 75kg.
In addition, if we include the planned decarbonisation of UK electricity and assume that future electricity will be cleaner, the fraction of embodied carbon becomes higher still - up to as much as 45 per cent more.
This demonstrates that it is a mistake to downplay the value of embodied carbon. That is not to say that day-to-day operational emissions are not important. They are. However, we need to pay equal attention to both areas if we are to make genuine progress in sustainable building.
It could also lead to confusion for those who have put time, effort and energy into analysing the embodied carbon of their own construction practices. Has it been a waste of time? Should they have just poured all their attention into cutting energy costs?
I want to reassure construction and property companies, many of which have made some great strides in this area, that their efforts have not been wasted.
As World Green Building Week kicks off today, let's not lose the impetus to address the issues of embodied and operational carbon. If we're going to make progress in really reducing emissions we need to deal with both. Not one at the expense of the other.
Dr Craig Jones is a senior associate at Sustain