Embodied carbon: What it is and how to tackle it

Embodied carbon

Embodied carbon is the amount of carbon emitted during the construction of a building. The extraction of raw materials, the manufacturing and refinement of materials, transportation, installation and disposal of old supplies can all produce embodied carbon emissions. Essentially, embodied carbon is built into the fabric of building.

Operational carbon

Operational carbon is the amount of carbon emitted once a building is in use. It’s easier to measure than embodied carbon and has been a reduction priority for a while now. The aim is to retrofit existing structures and design new buildings with energy efficient practices, including monitoring and lowering the emissions from heating, cooling, and the management and maintenance of a product or structure.

Regulating embodied carbon

Embodied carbon has moved a lot higher up the agenda for industry and government.  While it currently accounts for 11% of greenhouse gas emissions, with the projected increase of construction initiatives over the coming decades, it’s believed that by 2050 embodied and operational carbon emissions will be the same.

Industry leads are currently backing proposals for legal limits on embodied carbon. This would see an amendment to the Building Regulations known as “Part Z” which would enforce:

• Mandatory limits for upfront carbon emissions on al building projects over 1,000m² from 2027
• Construction firms to assess and report on whole life carbon on all non-residential projects over 1,000m² from 2023 and residential projects from 2025

Building for resilience

One of the main methods to reduce embodied carbon is by using more resilient materials that will last longer and are often produced via a more efficient construction process. Adopting these changes will reduce capital expenditure as well as maintenance, repair and replacement costs.

Embodied carbon and planning consent

Cost benefits aside, demonstrating your commitment to reducing embodied emissions is quickly becoming a key consideration in obtaining planning permission. Several local authorities - including Westminster City Council, Brighton, Oxford, Hammersmith and Fulham, Camden and City of London - have started to enquire about the embodied carbon footprints of developments. Having an embodied carbon evaluation may soon make all the difference in the planning process.

BREEAM, LEED and Green Star are all building rating systems that recognise embodied carbon measurement and mitigation as part of minimising the impact of a building’s life cycle.

Reuse buildings

Renovation projects usually save between 50–75% of embodied carbon emissions compared to constructing a new building. If the foundations and structure are already preserved, most of the embodied carbon will already be there and this drastically reduces new emissions.

Use low-carbon concrete mixes

Concrete can be the biggest source of embodied carbon for a new site, but lower-carbon concrete is easy to develop. By working with structural engineers, you can use fly ash, slag, calcined clays or lower-strength concrete if possible.

Use less carbon-intensive materials

Aluminium, plastic and foam insulation all have high carbon footprints so try to use alternatives or use them sparingly if you can. A wood structure is a good alternative to one of steel and concrete for example. And straw and hemp are annually renewable options for insulation.

Reuse materials

Second-hand materials such as brick, metal, wood and even broken concrete can make a big difference to embodied carbon emissions. These salvaged materials have a lower carbon footprint as the carbon used to make them has already been spent. Steel that’s brand new has an embodied carbon footprint five times greater than recycled content steel.

Use fewer finishings

Another way to use less embodied carbon is to use structural materials for the finishing touches. Polished concrete slabs make a good alternative to carpet or vinyl and unfinished ceilings can cut emissions dramatically.