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.

Photo credit: Henning Larsen/Rasmus Hjortshøj

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The first step to achieving our decarbonisation goals is to understand where the carbon is in our buildings. For this, we need consistent data, which allows us to make comparisons and understand best practice.

But up to this point, this data has either been unavailable or inadequately shared, posing challenges to effective decision-making and decarbonisation efforts in the built environment. It is this issue Ramboll aims to tackle by launching CO2mpare.

With this database it is now possible to:

Review typical upfront carbon levels in buildings across six countries and 10 typologies
Use the interactive filters to compare average carbon impacts of new-builds vs. renovated buildings
See the average distribution of carbon across the dataset

In developing CO2mpare we have incorporated carbon assessments from different countries with different methodologies into a single system that allows for comparisons. But since there are big differences in how each country counts carbon, this is not a simple exercise – a point I will return to in this article. We recognise that this is only the start, and caveats remain in how we can compare the data.

For every m³ of concrete that we demolish and replace with new concrete, we release around 300kg of new CO₂e.

Paul Astle

Decarbonisation Lead at Ramboll

Nevertheless, we’re sharing our data and interface now without restrictions because we recognise that the urgency and importance of tackling climate change requires the industry to collaborate and work together.

What is CO2mpare?

As an international design and engineering consultancy, Ramboll has building projects across the globe. Increasingly these projects include a carbon assessment, and it is this data Ramboll is now making freely available in an anonymised form from +130 projects worldwide.

CO2mpare has therefore been developed to allow the collection and organisation of different projects with different carbon assessments to enable comparison.

This follows work from 2023 when Ramboll published a whitepaper on some of the challenges associated with the range of carbon assessment methodologies and their differing scopes.

In this article, I will explain how you can start using the database today to get a better sense of the average carbon impact of specific building types.

Click here to begin exploring CO2mpare.

Renovating is an overlooked sustainability driver

Within our current dataset, there are some trends which stand out.

First, we see clear evidence for the huge potential carbon savings that can be made through the renovation of buildings compared to new build. It is further proof that our existing assets and buildings have value that can be retained – in the embodied carbon already invested in them. For example, for every m³ of concrete that we demolish and replace with new concrete, we release around 300kg of new CO₂e, so any buildings and elements that we can retain and reuse can help us save those emissions.

Refurbishing and transforming existing buildings is an area that Ramboll is actively pursuing as a business and supporting our clients with. Ramboll sees this as a key opportunity to save carbon, value and, often, cost.

Images for Paul Astle article Sustainable buildings need data. So we shared ours about CO2mpare database — In CO2mpare you can see average carbon footprints for different building types in different countries.

The database currently includes 138 different building projects in northern Europe, but we continue to gather data across all regions to build up a broader international dataset to further expand CO2mpare and make it even more useful.

This emphasises the importance of getting more and better carbon assessment data from renovation projects as well as new build projects. This is a challenge, as building transformation projects are often unique and include a variety of different levels of intervention as well as often being part of an extension project. We have included the functionality in our database to isolate out the renovation part of a project to allow future filtering as we build up the data from hybrid schemes. It is also likely that we will see efforts to limit the carbon spent on renovations as well as new build projects to support efforts to stay within a global 1.5-degree carbon budget.

Is comparing countries like apples and oranges?

When reviewing the data, we also see some differences between different countries. Take Denmark and the United Kingdom. While at first glance it would seem that projects in Denmark have a far lower carbon footprint than the UK, there are some likely reasons for potential differences. The database uses carbon assessments created as part of nationally agreed methodologies and whilst we have sought to minimise the differences in the data, some will remain, for example floor area definitions and, in the case of Denmark, the treatment of biogenic carbon. So a more likely candidate for the differences is due to differences in the carbon factors – again these can be set at a national level or may depend on the level of detail that has been sought during the assessment.

Going forward, the ambition is for CO2mpare to include both material data as well as carbon data. This will allow users to isolate differences in carbon factor from differences in material efficiency. This will also enable identification of best practice in both material efficient solutions as well as the lowest carbon materials and products to use.

These differences further reinforce the need for a more accurate and transparent methodology for assessing the carbon footprint of buildings, one which allows objective international comparisons. As it stands, if we build two identical buildings in Denmark and Sweden, we will get two different carbon footprints because of how each country regulates standards for life-cycle assessments.

The first step, not the last

In addition to data, many other gaps need to be closed. For instance, there is no internationally agreed set of standard typologies for buildings and there remains variation in countries and design disciplines. So we see this as the first step towards a more unified approach, which will require us all to continue sharing best practices in a transparent way.

We encourage you to begin exploring CO2mpare and use the filters to examine the similarities and differences. Ramboll will be updating this tool with more data and functionality in the future to improve carbon knowledge. This will support our clients and the wider industry to accelerate the decarbonisation of the built environment and meet our collective goals.

Want to know more?

Paul Astle
Decarbonisation Lead
+44 7436 545367

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