Demolish or Upgrade:13 June 2023
I recently attended the “Build Green Now” Conference, organised by the Irish Green Building Council, during which a feast of detailed knowledge was served which, as always, both educated and inspired all who attended. Retaining existing buildings was a major topic and an interesting comment was made during a panel discussion when a member was commenting on what was the best piece of advice they could give in terms of minimising embodied carbon. The response was simple, the most important piece of advice was that a conversation with the client, at the outset of the project, about retaining existing buildings and embodied carbon actually takes place.
In the commercial world retaining an existing building may not be appropriate for numerous practical reasons depending on the nuance of a project but there is an importance in having as a baseline philosophy that “The greenest building is the one that already exists” (1). Making this mantra the starting point for all projects would mean that this conversation has to take place at the outset of a project so that the type of “build” can be established (Nothing, Less, Clever or Efficient).
Fig 1. One-Click LCA “Decarbonizing Construction” report.
Commercial clients are now well aware of ESG portfolio necessities along with other current or impending legal requirements in terms of Carbon Emissions. It is important that all parties are aware from the outset that with the ongoing decarbonization of the grid and minimization of building operational energy use, that the importance of retaining and upgrading existing buildings, in order to minimise the “Upfront Embodied Carbon” of a project, is now something that needs to be explored at the outset in order that a client can have advantage of the full carbon reduction potential of a project.
Fig 2. Carbon Leadership Forum - Relative impact of embodied and operational carbon of a new building from 2020-2050
In order for a project to minimize it’s “Upfront Embodied Carbon” one of the most effective strategies is to reuse an existing building rather than demolishing and constructing a new one. This is due to the fact that sub-structure and structure houses a large percentage of the “Upfront Embodied Carbon” total. So even if the façade cannot be retained a substantial cut in embodied carbon can be achieved by retaining structure and sub-structure alone. This aligns with current “Lean” Structural Design philosophy which should be an essential part of the conversation at the outset of every project. In a “Lean Design” guidance document available on the UK institute of Structural Engineers the first 2 points are “1. Don’t Build!” and “2. Upgrade existing buildings wherever viable” (2).
Fig 3. Building.co.uk - Breakdown of “Upfront Embodied Carbon”
If appropriate for the project, the decision to refurbish and upgrade an existing building puts a project immediately on a lower trajectory in terms of carbon emissions from that of a new build.
Fig 4. AECOM diagram: Illustrative whole life carbon emissions in newly built and refurbished buildings
However, in practice, there can be some obstacles to being able to have this conversation at the beginning of a project. Further feedback I received from the “Build Green Now” conference was that some offices found carbon calculation (even high level calculations) to be complex in terms of skills required, time involved and understanding what standards need to be followed. Not having the proper carbon calcs available seemed to trigger an inertia and a reluctance to discuss the topic of embodied carbon at the beginning of a project. This is a situation to be avoided.
Luckily Voltaire left us with one of the world’s most helpful quotes, “Perfect is the enemy of good.” and an example of this would be a method that MCA used at the outset of the recent award winning Dockline project in the IFSC (3).
Fig 5. MCA Dockline (IFSC) Project
Fig 6. MCA Dockline (IFSC) Project
Fig 6. MCA Dockline (IFSC) Project
Here the focus was put on calculating what percentage of reusable materials was possible so that this information was available upfront at the outset of the project.
Fig 7. MCA Dockline (IFSC) Project – Percentage of Reusable Materials Table
With the knowledge that retention of structure and substructure are your big wins, this type of information can be refined in terms of accuracy and translated into carbon calculations as the project develops but the goal of not allowing the embodied carbon moment to pass at the project outset is achieved, and that can make all the difference.
(1) Carl Elefante https://www.architectsjournal.co.uk/news/opinion/the-greenest-building-is-the-one-that-already-exists
(2) Lean Design: 10 Things to do now https://www.istructe.org/journal/volumes/volume-98-(2020)/issue-8/lean-design-10-things-to-do-now/
(3) MCA Dockline IFSC Building https://www.linkedin.com/posts/mca-architects_retrofit-architecture-design-activity-7034860411711553536-OKMr?utm_source=share&utm_medium=member_desktop
Fig 1: One-Click LCA “Decarbonizing Construction” report. https://www.oneclicklca.com/decarbonizing-construction-report/
Fig 2. Carbon Leadership Forum - Relative impact of embodied and operational carbon of a new building from 2020-2050 https://carbonleadershipforum.org/embodied-carbon-101/#:~:text=In%20the%20building%20industry%2C%20embodied,due%20to%20building%20energy%20consumption.
Fig 3. Building.co.uk - Breakdown of “Upfront Carbon” https://www.building.co.uk/data/sustainability-net-zero-carbon/5106428.article
Fig 4. AECOM diagram: Illustrative whole life carbon emissions in newly built and refurbished buildings https://aecom.com/without-limits/article/refurbishment-vs-new-build-the-carbon-and-business-case/