CO2mpare: Setting the benchmark on carbon in buildings

Have you ever faced difficulties comparing carbon data for different buildings? It’s a common problem and not surprising given the lack of consistency and transparency in carbon assessment data for buildings. This is the challenge that Ramboll’s CO₂mpare carbon benchmarking database is seeking to solve by organising and standardising data across different carbon assessment methodologies and definitions.

Kiasm and Cityscape © copyright / Credit KPF

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Worldwide, buildings are responsible for 37% of global energy-related CO₂ emissions, 34% of energy demand, and 50% of materials consumed. Better quality and more consistent data is critical to reducing these impacts as it enables the industry and policymakers to draw comparisons and set sustainability benchmarks for buildings as well as glean insight into best practices.

World’s first open access buildings carbon benchmarking tool

To address these challenges, CO2mpare was launched as the world’s first open access, interactive carbon benchmarking tool for buildings at the Buildings and Climate Global Forum in March. The platform has recently undergone a major upgrade that is revealing new insights into sustainable construction.

More assessments, more scope, more transparency

Following the upgrade to CO₂mpare, the number of assessments included in the database has increased by over 50% to 203 across 7 countries and 11 building typologies; increasing confidence in comparisons.

One of the greatest inconsistencies in carbon assessments is the different scopes that they cover. In the updated version of CO₂mpare, 12 scope combinations have been included with an associated graphic to make it as clear as possible what scope is covered in the view.

Furthermore, the reference data has been expanded to encompass data from B and C lifecycle modules as well as operational carbon data (B6) where available. This more holistic data set can reveal the most significant sources of carbon over the life of a given building as well as where that carbon is at the time of construction.

Benchmarking carbon intensity and concrete usage

CO₂mpare now also goes beyond carbon and provides a much-needed indicator of building material use intensity by displaying the Concrete Usage Index (CUI), which measures the volume of concrete per m². Understanding both the carbon intensity and the concrete usage is key in tackling carbon reduction in concrete and resource consumption more generally.

Figure 1: Comparison of average Concrete Usage Index by building type

Ramboll has already been focusing on improving the efficient use of concrete with innovation in concrete forms as well as displacing concrete through the use of innovative timber structures.

New insights on carbon investment in different scenarios

CO₂mpare is already revealing several significant patterns that are topical for the construction value chain. For instance, in relation to the increased market interest in whether to build new developments or renew existing building stock, CO₂mpare shows that across all geographies and building types, there is a substantially lower carbon investment for refurbishments.

Figure 2: Comparison of carbon investments for new builds and renovations

The building data also allows users to see the distribution of carbon and building height. Historically, the assumption has been that the taller a building, the higher it’s carbon intensity. The data indicates a large spread of carbon intensity up to around ten storeys.

However, whilst we have fewer data points beyond this, the carbon intensity of tall buildings does not appear to significantly increase with height. We will be monitoring this trend carefully as we get more data to better understand the carbon efficiency of taller buildings.

Figure 3: Distribution of carbon by building height

Future development of CO₂mpare

Paul Astle, Decarbonisation Lead for Ramboll, concludes, “Going forward, we’ll be continuing to gather more data across Ramboll to allow us to gain a clearer understanding of specific trends. In addition, we’re working to enhance the granularity of our data collection, which will unlock more detailed insight in areas such as structural design and energy performance. Look out for further updates in 2025.”

Visit Ramboll CO2mpare to explore more

Want to know more?

Paul Astle
Decarbonisation Lead
+44 7436 545367

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Sustainable buildings need data. So we shared ours

For the first time ever, Ramboll is making its carbon data for buildings openly available for all stakeholders across industry and governments by launching the CO₂mpare database. The goal is to close the data gap and, essentially, build better buildings.