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What growing interest in embodied carbon means to the construction industry

In the last couple of years, there has been a lot of work to map out policies to reduce carbon in homes and businesses across the UK, which now has some of the most ambitious carbon reduction targets in the world.

A whole host of legislation including Energy Performance Certificates, Display Energy Certificates, the Building Regulations (part L), zero carbon targets and inventive ways to reduce and finance reduction in operational carbon emissions and further Government policy is seeking to encourage consumer’s behaviour when it comes to energy use.

But does this focus on operational energy use come at a cost to total carbon emissions? Embodied carbon is proportionally a big emitter, released when a product is manufactured, shipped to a project site and installed and these are ‘now’ rather than future emissions. It also covers the maintenance, alteration and demolition of a building, including contractor’s emissions and, according to RICS research, can account for up to 62 percent of a building’s whole life emissions. Many of the solutions to provide zero carbon operational carbon emissions may have high carbon intensity and by 2019, embodied carbon will make up 100 percent of a building’s carbon footprint (excluding transport emissions).

Measuring and mitigating embodied carbon often finds itself in the ‘too hard basket’ whereas measuring operational energy aspects, such as fabric measures, lighting, heating, air-conditioning avoidance etc, are easier with gains and costs easier to apportion.

Difficult or not, factoring embodied carbon into a building’s emissions is likely to soon be a legal requirement given the higher priority that it’s getting from a number of avenues including; the UK Green Building Council, the Government’s Chief Construction Advisor (Paul Morrell) the Technology Strategy Board and now the RICS in their Redefining Zero Report. This report goes some way towards making the case for embodied carbon but there is still some way to go before we get a workable methodology and a tool that the industry can use. 

SO HOW CAN YOU MEASURE EMBODIED CARBON EMISSIONS?

There are many challenges in trying to measure embodied carbon, by its very nature it is particularly hard to quantify. Not least, trying to estimate retrospective carbon emissions from a long time ago is difficult owing to the lack of data available. Multiple sources of embodied emissions data do exist, but they are not necessarily consistent or applicable to construction products. 

There is also a range of embodied carbon calculators available but they do have shortcomings. They only give a partial picture of what is happening without providing any insight into how the reduction of one set of emissions affects the other. While footprinting gives a better picture again, it has its problems. It lacks a degree of accountability and any durability analysis as it “assumes” all the resource allocation decisions that will take place not only today but also over the extent of a building’s life in terms of building materials etc.

To develop an accurate picture of carbon emissions, it is important to get a clear definition of what is included i.e.; Cradle to gate, cradle to site, cradle to grave? Data needs to be measured in real time, as predicting future carbon emissions introduces an element of uncertainty into the figures and makes current decisions void if the data is different to that assumed. Data also needs to reflect decisions that have been made. 

It is sometimes difficult to calculate measures of embodied carbon unless there is a high degree of contextual knowledge, which puts a project team member such as a quantity surveyor in the best position to make an assessment. The quantity surveyor is well placed to pick up this ‘carbon accountant role’ as they are near the quantities, the cost, the specifications and the supply chain. Identifying the weakest link of buildings and components is a key part of keeping carbon wastage to a minimum.

WHAT THE INDUSTRY NEEDS

One of the most important, and still missing, factors is the need for a common, robust metric to calculate and measure all emissions of a building.

Faithful+Gould and its parent company Atkins are collaborating with other experts in this area and soon hope to release a free to use tool that will help teams quantify embodied carbon for projects.  The tool is a web based application and is currently being tested internally and with a number of external experts. Other firms are working on similar projects, but the industry needs to unite to deliver consistent methodology and data sources.

Steps are being taken to provide consistency in this area. CEN TC350 is a technical committee set up to develop and implement European standards to cover the sustainability of buildings, which includes the measurement of embodied carbon and the lifecycle of building components. Although not compulsory, these standards will provide a European wide guide for the industry that will be in place when measurement of embodied carbon becomes regulatory – as it inevitably will. 

There needs to be common agreement on a simple, easy to follow and widespread set of guidelines that effectively measure and monitor carbon emissions in buildings. These can then be incorporated into existing legislation and guidance such as BREEAM, carbon standards, Code for Sustainable homes etc to build on the success seen in operational energy use to total carbon emissions.

Sean Lockie is director of sustainability at Faithful+Gould