The emissions beneath your building: Foundations
The emissions beneath your building: Foundations
No matter how ambitious your carbon reduction targets are, you can only design for the ground you’re given. Ground conditions inform what foundation system you’ll need, sometimes more than design concept itself. And in many cases the footings then shape the emissions profile of the entire project. For projects seeking a low-carbon outcome, the challenge often starts below grade.
Foundation type = Footprint
Different ground conditions demand different foundation systems and the deeper or more reinforced they are, the more carbon they tend to carry.
Piling is the most carbon-intensive option. It’s used when the ground is too soft to support a building’s weight and requires driving long, reinforced concrete columns deep into the earth. It uses large volumes of concrete and steel, and calls for heavy equipment like piling rigs and cranes.
Deep pad footings are used when moderate ground strength is available. These are thick concrete pads at the base of columns that distribute loads more widely but still require significant excavation and reinforcement.
Shallow pad footings are more viable when ground conditions can bear loads closer to the surface. These footings are smaller, use less concrete, and produce lower emissions.
Minimal footings are possible on sites with strong bedrock. Here, the ground itself provides sufficient structural support, making it possible to avoid deep excavation and heavy reinforcement.
As Tom Dean, Director of Carbon Planning, puts it:
“You can bring the best low-carbon design in the world - but if the site needs piling, that will make a huge impact on your emissions.”
The key takeaway: the less supportive the ground, the more intensive the foundation, and the higher the carbon cost.
Your site sets the limits
The very same building could generate significantly different embodied emissions depending on the ground conditions where it’s built.
Softer ground often requires deep piling, but can make basement construction more viable. Both systems use large quantities of high-emission materials such as concrete and steel, and once they're selected, there's minimal room to reduce emissions.
By contrast, stronger ground - like rock - can accommodate shallow or even minimal footings, often without the need for a basement. This results in a much smaller structural footprint and significantly reduced embodied carbon.
That’s why assessing ground conditions early can be key in setting realistic and achievable embodied carbon targets.
Because while you can control what happens above ground, your footing requirements may make reducing emissions much harder.
