Kilograms of carbon dioxide equivalent per estimate line, from sourced factors.
Costing and commercial control. 5 questions answered below, each with the arithmetic behind it and the limits of what the tool decides. Open the Embodied Carbon Estimator tool.
Embodied carbon is the emissions that come with making and moving a material, before the building is used at all. It is calculated by multiplying a quantity by an emissions factor, which is why this tool starts from measured quantities rather than from a floor area and a benchmark. The consequence is that a carbon figure is only as good as its factors, and factors come from published datasets that differ by region and by production route. Where a material has no factor, the tool reports the gap rather than applying a generic one, because a made up factor produces a number that looks like an assessment and is not. Two specifications can then be compared on the same basis, which is where most of the value sits.
Fifteen cubic metres of concrete at a factor of about three hundred kilogrammes per cubic metre is four and a half tonnes, and twenty tonnes of reinforcement at roughly one and a half kilogrammes per kilogramme is thirty tonnes, which is usually the surprise. Change the concrete to a blend with a lower cement content and its line falls by a third while the steel stays where it is. The comparison shows that the steel dominates, which is not where most people look first.
Quantity multiplied by emissions factor, per material, then summed. The quantity comes from the calculators, so a bill and a carbon figure share the same measurement. The factor comes from a published dataset and is stated per material and per unit, which means the result can be checked line by line by anyone with the same dataset.
It is reported as uncounted and left out of the total, with the gap shown. Applying a generic factor to a material with no published value would produce a number that looks authoritative and cannot be defended, and carbon figures increasingly end up in planning documents where being wrong matters.
Material supply, transport to site and the construction activity itself, kept apart so each can be seen. Operational energy over the building's life is not included, and neither is end of life demolition and disposal unless they are added. That boundary is stated rather than implied, because a carbon figure without a boundary means very little.
Yes, and that is the main use. The same quantities are priced against two specifications, so the difference between a standard mix and a blended one, or between two insulation products, is a number rather than a claim. Because the quantities are identical in both runs, the difference is attributable to the substitution.
No. It is an estimate for comparison and early design, not a certified assessment. Certification involves verification, a defined methodology, an assessor and a declared boundary, and the figures here are one input to that process rather than a substitute for it. Used that way it is genuinely useful, because most of the reduction available on a project is decided long before an assessor is appointed, at the point where the frame and the envelope are chosen.