It’s time to think deeper about reducing embodied carbon and retrofitting existing buildings presents the perfect opportunity.
Achieving net zero requires a new approach from the built environment sector. For years we have understood the requirements to reduce carbon emissions when we occupy and operate buildings. However, if we are to meet the goals set out in the Paris Agreement, then we must also apply equal effort to reduce the amount of carbon expended in producing the materials our buildings are made from.
Reducing embodied carbon in built assets means focusing not just on the energy use of a building, but on the energy it requires from transportation to raw materials, across the design and construction phases and throughout the supply chain. It’s on this basis that retrofitting existing buildings offers the extraordinary potential to reduce the overall carbon impact of creating places to live, work and play.
I have closely followed several of our key projects where clients have purchased existing office assets and committed to extensive retrofitting and repurposing. Each time, most of the building structure and façade has been retained, while refurbished office space along with health and wellbeing facilities have been created.
These projects compare on a like-for-like basis to new build assets in the same market, including metrics such as operational energy performance. But the biggest difference in terms of the carbon story is that they represent significantly less embodied carbon compared to a new build. On this basis, the reuse and repurposing of existing buildings should be a fundamental part of the built environment sector’s strategy to combat climate change.
Looking at some stats on the subject helps highlight the significance of the impact retrofitting buildings can have compared to building new. A typical new office, built to current building regulations, would result in 34% of the carbon emissions being from the embodied energy of the original building materials and the subsequent assets renewed in its lifetime. So, a third of carbon emissions are tied up in the constituent parts of the building. If we can reuse existing buildings rather than knocking them down and build new, we can tackle this “hidden third”.
Another way of looking at the significant impact of reusing buildings is looking at the proportion of embodied energy of individual building elements. Again, in a typical new-build office, the embodied energy within the superstructure is 48%, the substructure is 17% and facades are 16%.
This means that a total of 81% of the embodied energy is tied up in elements that could be reused. So, if you have an existing building, why not reuse it, and save a significant portion of that 81% that would have gone into building all those elements from scratch. This represents a huge potential for the built environment sector to reduce carbon emissions.
Similarly when looking at how to reduce operational carbon emissions, altering or replacing sub and super structures of buildings has the least potential to reduce future operational emissions. Whereas replacing the building services, which represent a low percentage of emobodied energy, has the highest impact on reducing operational energy.
At TB+A, we help our clients evaluate the options to repurpose buildings to achieve these net reductions in whole life carbon and we support industry initiatives such as the Architects’ Journal #RetroFirst campaign.
This campaign has one of the most memorable straplines associated with promoting environmental awareness in our sector: “The greenest building is one that already exists”.
As experienced MEP design engineers working across the property and construction sector in the UK and Ireland, we are aware of the many challenges working with existing buildings can represent. However, we equally know how inventive our industry can be.
When faced with challenging 1960s, 70s, or 80s structures, creative solutions can include repurposing to an alternative building use such as residential or hotel. In the office sector, exposed services and integrated MEP/structural solutions can create welcoming spaces that achieve a sense of headroom and space that suspended ceilings never could when working with low floors to soffit heights.
Looking ahead to what might focus attention during the forthcoming COP26 summit, retrofitting existing buildings offers a significant opportunity for the property and construction sector to contribute to driving down carbon emissions in line with the UK and international targets and achieving the net zero targets we’ve been aiming for.
This blog was first published on Troup Bywaters + Anders’ website.