Balancing cost and carbon: industry professionals share the challenges

The drive to reduce greenhouse gas emissions from the built environment is gaining momentum in the industry, despite lack of a national mandate on whole life carbon assessments.

As construction firms increasingly look to run projects with sustainability in mind, the inevitable question follows – how much more will it cost us?

This is particularly relevant when considering materials choices because the difference between options available isn’t always immediately obvious. Costs fluctuate and carbon data can be difficult to use in direct comparisons. Finding the balance between the two to arrive at an informed decision can be far from straightforward.

BCIS CEO James Fiske, also chair of the Built Environment Carbon Database (BECD) steering group, said: ‘We used to talk about the time, cost and quality triangle, three factors which are intrinsically linked on projects. If you changed one, the others were inevitably affected.

‘Now we’re rapidly moving to more of a square, with the addition of environmental impact becoming as important as the other considerations. The choices you make around carbon can have a significant impact on cost, quality and time.’

In a recent poll of construction professionals*, we asked, on the projects they had worked on recently, how many had carbon reduction as a prioritised objective.

The majority – 63% – said ‘some’, while 19% said ‘none’ and just 13% said ‘all’.

Fiske said: ‘At the moment there is a wide spectrum of how carbon reduction is treated, much of which – since whole life carbon assessments are not mandated – simply comes down to client priorities.

‘On one end you’ve got projects where cost is everything and carbon values are currently given little, if any, regard. On the other, you’ve got sustainability and carbon reduction afforded the utmost priority, no matter what the cost may be. The majority of projects of course lie somewhere between the two.

‘In every project, there’s a balance to strike between time, cost, quality and emissions – how individual firms and professionals gauge the importance of each and give weight to them varies considerably.’

We also polled construction professionals on what the top three considerations had been when choosing materials on recent projects. First was cost, chosen by 34% of respondents, second was quality (24%) and third, lead times (18%). Embodied carbon had just 10% of the responses, and operational carbon, 5%.

However, expectations for projects in five years’ time show an anticipated shift. While cost remains the expected top priority with 28% of responses, respondents think there will an increase in the importance afforded to embodied carbon (24%) and operational carbon (16%).

Fiske said: ‘We know there’s an appetite for change in the industry and many cost professionals want to be working on a cost and carbon basis, because they know the combined consideration leads to the best-informed decisions on projects.

‘Frankly, it’s the most efficient way to work – to link carbon measurement into existing measurement processes that already happen on construction projects in cost estimating, reporting and control.

‘This change in approach is increasingly evident and the industry is pushing forward, even if we are lacking a national mandate. In our poll, the majority (59%) of construction professionals told us they work for a firm which has a net zero strategy.

‘But, with all the will in the world, what we do know is that you can’t make informed decisions unless you have the right data in front of you. Part of the experience of developing and launching the BECD has been to discover the myriad of ways in which carbon data can be tricky to work with.

‘The truth is that, while we have a rich history of cost data – and we have more than 60 years of that at BCIS – we simply don’t have the same in the industry for carbon. The pool of data is growing, but it’s really in its infancy.

‘We’ve identified three main challenges, which are around availability, quality and volatility. In simple terms, availability is improving and the volume is increasing, though this in itself is showing up more of the inherent problems.

‘There are inconsistencies within and between Environmental Product Declarations (EPDs). Sometimes even mandated fields have not been completed. The biggest challenge is where there are inconsistencies in units of measure – how can you properly compare two products when one is measured by linear metre and the other by square metre?

‘That’s one of the things we’ve looked to address in our BCIS Life Cycle Evaluator, which includes converted values to make the data consistent.

‘We’re used to volatility from a cost point of view, but carbon data also changes for various reasons. Manufacturers change processes, there’s the effect of decarbonisation of the grid, and revisions are always possible before the expiry date, which you might not pick up on if you just have it saved away somewhere.’

We asked respondents if they struggle to compare the carbon values for different materials because of inconsistencies between EPDs. Just over half (52%) said they do sometimes, while 23% said they always do, and 20% said they do occasionally. Just 3% said they rarely struggle, and 2% said they never do.

Of course, it’s not only working with carbon data that can be challenging. Materials prices are frequently on the move, which can make comparisons less straightforward.

Fiske said: ‘The volatility of materials cost inflation in the last couple of years has proven just how vulnerable best-laid cost plans can be, so anything we can do to help make those comparisons between products easier is hopefully really useful.

‘We have included past and forecast future inflation in our Cost and Carbon Materials Database to show that, for example, Product A and Product B might be a very similar price today, but in 12 months’ time, the data we’ve pulled in from our forecasts predicts a steeper increase in one over the other, and that could be the decisive factor.

‘Looking forward, we’re developing a service that will bring together whole life cycle cost and carbon calculations. This will enable construction professionals to factor in every stage of a building’s life and fully assess where the balance of cost and carbon lies.’

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View the full results of our poll on balancing cost and carbon choices on projects.