As you break down the individual materials that contribute to the whole building, you will find that they follow a similar pattern; large amounts of carbon in the manufacture, processing and transport of the material to the building site.

It is truly staggering to think that by the time the building is first occupied that over 50-55% of the total lifetime carbon impact is already in the building!

Fundamentally, there are four key things to consider to meaningfully reduce embodied carbon in a building:

1. Repurpose or reuse existing buildings
2. Reuse, re-manufacture and recycle building materials
3. Build with low carbon, natural (less processed) materials
4. Offset emissions (renewable technology or woodland planting)
   

1. Repurpose or reuse existing buildings

Maybe the most obvious (to some) would be to use the existing building stock that we already have to re-purpose, rather than razing to the ground and starting from scratch. A lot of discussion has been had recently about how ‘eco’ buildings really are if they use a huge amount of carbon in their construction, despite how highly insulated and traditionally energy efficient they might be. As per the diagram above, if large proportions of the building structure can be retained almost 50% of the embodied carbon can be saved compared to a new building.

2. Reuse, Re-manufacture and recycle building materials

The next best option if the form of the building really has to change is to use the existing materials on site and reuse or recycle. A classic example of this is the demolition of concrete structures, on-site crushing and using the demolition material for hardcore for new foundations or floors. With a bit of thought and planning this reusing of materials can not only dramatically reduce embodied carbon but save costs of disposal and transport to site.

3. Build with low carbon, natural (less processed) materials

If the previous two ways to reduce carbon have been exhausted the next best option is to source materials that are lower carbon and more natural. Less processed artificial materials by their very nature have had less energy used in their production and so have less of a carbon impact. Using cellulose or sheeps wool instead of glass fibre and PIR is a classic example, but also using some natural wood products in moderation can help dramatically reduce carbon compared to more traditional masonry and concrete construction methods. As a first step, understand the relative embodied carbon impact of materials familiar to you.

4. Offset emissions (renewable technology or woodland planting)

Finally and as a last resort, particularly for commercial developments you can resort to offsetting embodied carbon emissions by investing in off-site renewable technology; such as offshore wind and woodland planting. There are a growing number of legitimate and recognised companies that support Gold Standard and global projects which can be invested in and offset a project’s embodied carbon.

If you have any questions about the RIBA 2030 Climate Challenge, please don't hesitate to contact the Mesh team today.