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Cutting carbon contractually

Between 2019 and 2022, carbon emissions per tonne of asphalt produced in Norway fell from 60kg to 47.5kg. The 20% reduction has been driven by Norway’s public roads authority Statens vegvasen which takes carbon costs, as well as financial ones, into account when assessing tenders.

Having set a target to halve the carbon footprint of asphalt used in construction and maintenance by 2030, Statens vegvasen laid out its strategy for achieving that in 2017. As well as deciding to drive the reduction contractually, the authority gave contractors and suppliers plenty of warning with stepped targets mapped out over the coming years.

“Predictability is the key to success,” Statens vegvasen’s chief engineer Thor Asbjørn Lunaas told the E&E Event 2022 in Vienna in November, run by Eurasphalt and Eurobitume.

The contractual mechanism works like this: contractors must submit carbon emissions as well as financial costs. The bidder with the lowest carbon emissions received no adjustment to its financial bid. The others all have their financial prices adjusted, with 5NOK (€0.5) added on for every kilogram their carbon emissions come in above the lowest carbon bidder.

The proportion of contracts that would be tendered using the carbon weighting was also planned out, ramping up from 10% in 2020 to 100% in 2024. At the E&E conference, Lunaas said that almost 90% of contracts were already allocated using carbon weighting.

It seems to be working. There was a bit of a blip between 2019 and 2020 when carbon per tonne of asphalt rose from 60kg to 62kg, but now the figures are heading in the right direction. It was important to agree rules, said Lunaas, on elements such as how Environmental Product Declarations (EPDs) are used and how biogenic binders – containing materials derived from plants – are taken into account.

The carbon emissions under scrutiny are embodied carbon from raw material extraction to the asphalt having been laid on the road, stages A1 to A5 in lifecycle assessment terms. Geir Lange, who heads up large asphalt projects for Veidekke Industri, laid out how contractors in Norway – which also tend to be the asphalt manufacturers – prioritised investment for reducing carbon emissions. The biggest potential reduction comes from switching the fuel type used at the plant and increasing efficiency, the second biggest reduction comes from using alternative binders and recycled asphalt and the third biggest reduction would come from looking at aggregates and additives.

The next step for Statens vegvasen is to change its contracts again to incentivise contractors to produce road surfaces that last longer, since that too will lower a road’s whole life carbon footprint. To do this it uses functional requirements so that contractors are free to choose their own asphalt as long as it meets those requirements. Asphalts with improved deformation and abrasion qualities are assigned a longer life and the contract is awarded to the lowest annual cost bid. This is calculated by dividing the bidding sum, adjusted for the carbon emissions, by the adjusted pavement life in years.

Statens vegvesen has reported on two of its initial trial contracts that had used this lowest annual bid cost method. One contract, Østfold, is predicted to achieve an increase in asphalt life of 3.6 years with carbon emissions reduced to 36.7kg per tonne of asphalt, while the Trøndelag contract promises 1.4 years longer life and emissions of 44.6kg.

These are encouraging results. Although it is worth noting that the first 20% carbon reduction will nearly always be much easier to achieve than the second 20%. But perhaps the main lesson to take away from Norway’s experience is that setting long-term goals with clear rules makes it easier for the industry to plan future investment.

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