Carbon reporting has become a crucial requirement in the construction industry, but the process is far from straightforward.
While project-level carbon reporting is meant to offer transparency and accountability, the reality is that many reports do not accurately reflect the actual carbon impact of construction projects. The reason? Fragmented data, inconsistent methodologies, and a lack of real-time material tracking.
Why project-level carbon reporting falls short
Project-level carbon reporting aims to track and quantify emissions from materials, processes, and supply chains throughout a project’s lifecycle. However, significant challenges create major data gaps and inaccuracies.
Inconsistent carbon factors across teams
Different teams – estimators, designers, procurement teams, and contractors – often work in silos, using different carbon factors and methodologies. For example:
- Estimators rely on benchmark figures and industry averages when pricing bids.
- Design teams use Building Information Modelling (BIM) and specific Environmental Product Declarations (EPDs).
- Procurement teams prioritise cost and availability, often overlooking supplier-specific carbon data.
- Contractors work with invoices for the actual materials used in the building, which may differ significantly from earlier estimates.
The result? Discrepancies between estimated and actual carbon figures make it difficult to track true emissions. A closer look at why spend-based carbon reporting can exacerbate these inaccuracies highlights why moving to a data-driven approach is necessary.
Complex & ever-changing supply chains
Construction supply chains are highly dynamic. Material sources, suppliers, and specifications frequently change throughout a project’s lifecycle. This means:
- The supplier specified in the design stage may not be the one actually providing materials.
- Mid-project material substitutions often go unaccounted for in carbon calculations.
- Subcontractors source their own materials, but carbon data is rarely updated accordingly.
Without a real-time, integrated approach, project-level carbon reports reflect estimates rather than actual emissions.
The subcontractor data gap
One of the biggest challenges is capturing carbon emissions from subcontracted work. Many subcontractor invoices lack detailed breakdowns of materials used, making it difficult to calculate accurate carbon footprints. For example:
- Bespoke mixes (such as custom concrete blends) are often grouped into broad invoices.
- Multiple suppliers for a single item (like rebar from different steel plants) result in averaged estimates instead of precise data.
Without granular data, reported emissions can be significantly distorted.
Lack of integration between procurement and carbon reporting
Procurement teams typically focus on cost, availability, and compliance rather than carbon data. This often leads to:
- A disconnect between procurement systems and carbon reporting tools.
- Suppliers being asked for EPDs by multiple people within the same contractor organisation, causing inefficiencies.
- No centralised repository for emissions data, meaning calculations are repeated instead of leveraged at scale.
“We’ve got a real challenge – we have over seven thousand different suppliers that we're working with. We've got to get EPDs on different materials for each of our projects. Often, we're finding it's the sustainability teams who are asking for those EPDs from the suppliers. But you might have the same supplier being asked by multiple people from our side.”
Katherine Rusack, Head of Responsible Sourcing, Balfour Beatty
How to improve project-level carbon reporting
To make carbon reporting truly reflective of real-world data, construction firms need to move beyond traditional, manual reporting methods. Instead, an automated, integrated approach is essential.
- Automate data collection – Solutions like CausewayOne Carbon leverage invoice-based tracking, automatically assigning carbon factors to materials as they are procured and delivered to site. This eliminates reliance on outdated spend-based estimates and improves reporting accuracy.
- Centralise supply chain carbon data – EPDs and supplier-specific carbon factors should be stored in a central system, reducing redundant data requests and improving transparency.
- Bridge the gap between design, procurement & delivery – Standardising carbon factors across estimating, procurement, and construction will reduce discrepancies and improve project-level accuracy.
What’s next? Fixing carbon data gaps with digital invoicing
Achieving truly accurate carbon reporting requires addressing data gaps at the source. Digital invoicing plays a critical role in improving transparency by ensuring emissions data is directly tied to material procurement. By adopting solutions like CausewayOne Carbon, contractors can eliminate manual errors, gain real-time emissions insights, and track carbon data with precision across projects.
For more on how digital invoicing is transforming carbon reporting, explore how invoice-backed carbon tracking can help bridge critical data gaps and ensure more accurate sustainability reporting.
