We need to reduce carbon emissions, and transport emissions are part of that. However, [A4] transport emissions are only 1-2% of the whole life carbon emissions (LETI, 2020), so focusing on product stages [A1-A3] and operational carbon [B6-B7] has a bigger impact.
Transport is still part of the process and is part of the whole life carbon assessment three time [A2], [A4] and [C2]. Thinking about reducing transportation brings a different kind of thinking. Reusing what is already there, using local materials which can be repaired locally, reducing what needs to be transported to site, using the materials in a way that they can be used locally at the end of life.
Transport systems that reduce the carbon emissions are becoming more common with electrical systems powered by energy from renewable sources. As logistics becomes more sophisticated, there are reductions in half full vehicles being used and even e-cargo bicycles being used for small deliveries at hours when larger ones aren’t allowed.
The values come from the UK Government 2021 Greenhouse Gas Conversion Factors for Company Reporting published annually by the Department for Business, Energy & Industrial Strategy. The rings are based on values from the RICS Whole Life Carbon Assessment for the Built Environment report, for when the supply distance is unknown, which can be all the way to construction.
When I calculated transport carbon in the past, I always thought that the trips should calculated as full on the way to site and empty on the return journey as it is done in Finland (Ministry of the Environment, 2019). But the average laden values give a similar result and make the calculation process easier.
For the local distance of 50km, using the average HGV vehicle carbon factor it works out as 0.005kgCO2e/kg and using 100% to site and 0% on the return it works out as 0.004kgCO2e/kg.
As the distance increases to the national distance of 300km, again using the average HGV vehicle carbon factor it works out as 0.032kgCO2e/kg and using 100% to site and 0% on the return it works out as 0.022kgCO2e/kg. The average laden value provides an overestimation, which is conservative and encourages getting more accurate distances and methods. It’s a 50% increase, but on only 1-2% of the whole life carbon, your time would have a larger impact reducing other emissions in the project.