Embodied Carbon in sustainable Real Estate ESG
What is Embodied Carbon in Sustainable Real Estate Developments?
In the context of sustainable buildings and interiors, embodied carbon is essentially a question of materials.
Unlike ‘operational carbon’ or indeed ‘building energy efficiency’, embodied carbon accounts for the cumulative impact of building materials from extraction all the way through to construction; including transportation, manufacturing, and installation.
The embodied carbon of a given material is therefore the amount of carbon emissions involved in first producing it and ultimately deploying it in a construction project.
Embodied carbon impacts from building and infrastructure projects have been estimated to account for 23% of global carbon emissions (McConnell, Mithun).
In general terms, we can say that operational energy use has improved considerably as a result of sustainable green building principles, yet embodied carbon has lagged behind, remaining relatively constant over time despite the efforts of real estate sustainability consultants!
Due to the negative impacts of embodied carbon, and its inherent relationship with sustainable material procurement policies, it is an area of particular interest for sustainable building and interior consultants, such as ourselves.
How to reduce embodied carbon in sustainable real estate development?
The bulk of the opportunities come in the early phases (pre-design and design) of a real estate development project as a small number of construction material choices will carry massive weight in the final embodied carbon status of the building.
For this reason, project teams need to align behind sustainability objectives early on if they want to avoid playing catch-up.
Taking a step back further, developing a Sustainability Plan with objectives and priorities as early as possible, even doing so in broad principles for the development company as a whole in order to have an initial blueprint to apply as each new development deals comes online.
How to determine embodied carbon in building materials?
Completing Life Cycle Assessments (LCAs) is the main strategy to determine embodied carbon for materials or projects. Embodied carbon can be reduced by limiting material use, choosing low-carbon solutions, decreasing transportation related emissions, and reusing and recycling materials whenever possible.
Reduce Material Use in Sustainable Real Estate Development
An important strategy to reduce a real estate development project’s embodied carbon is to optimize and reduce overall material use. Sounds simple, perhaps deceptively so.
One major way to do this is to identify opportunities to use or repurpose existing buildings rather than demolishing or developing Greenfield sites.
Real estate projects designed with adaptive reuse in mind effectively plan ahead for this eventuality, baking in flexibility for future owners or developers to facilitate the process of repurposing old buildings or structures.
Demolition and construction is by comparison extremely carbon intensive, as it requires both material disposal and the extraction of new resources.
In addition, looking for efficiencies in the volume of certain structural materials used in a redevelopment or construction project will also diminish embodied carbon.
For example, research has shown that on average, the quantity of structural steel used in buildings can be up to two times the necessary amount from an engineering perspective, greatly increasing embodied carbon (Isaac).
Ensuring that material use is optimized and using stronger, more efficient materials will mean less volume overall.
In addition, the use of more efficient building strategies such as modular construction reduces waste and increases the sustainability of the project.
Other sustainable design decisions such as reducing the need for / specification of finish materials in favor of simply leaving certain elements of the building structure exposed also decreases overall material use, lowering a project’s embodied carbon and helping it achieve its sustainability objectives whilst also adding an appealing aesthetic dimension.
Summary - Material Optimization and Reduction Strategies
Use and repurpose existing buildings
Optimize structural framing by volume and materiality
Reduce material volume through efficient design choices
Implement modular construction methodologies
Using Low-Carbon Materials in Sustainable Real Estate Development
In any sustainable development project, it is likely that there will need to be some integration of new materials. Materials should therefore be selected based on the lowest feasible embodied carbon impact, commonly determined through the completion of LCAs.
LCAs consider the amount of carbon (and often other emissions) required to take a material through its entire lifecycle—from extraction all the way through to disposal. These analyses are invaluable to compare a project’s material options and the associated embodied carbon.
Whenever possible, select sustainable materials that have been manufactured using comparatively less energy or using renewable energy. Options with high recycled content, those that are bio-based and rapidly renewable will also help achieve sustainability targets, especially if they can also be reused at their end of life (McConnell, Greenbuild).
Healthy building materials such as cross-laminated timber (CLT), bamboo, cork, hemp, straw, sheep wool, and even mycelium are bio-based, carbon-sequestering options that can greatly reduce a project’s embodied carbon as part of a real estate sustainability strategy for example (“Whole Building”).
In addition, when choosing materials, it is important to consider their durability, specifically when calculated alongside local climate and weather patterns. It is essential to understand how different materials react to heat or moisture, for example, to make smart choices that will stand the test of time and not need replacing within a few years.
The more durable the material in the specific climatic conditions of the project location the less materials will be needed in future for upkeep and replacement, therefore reducing the risk of provoking additional resource extraction later on (“Whole Building”).
Sustainable interiors and embodied carbon
Most embodied carbon reduction efforts have been focused on significant structural elements such as concrete or steel, which require energy intensive processes and are often used in large quantities.
However, as substitutes such as CLT become more accessible, consideration for the embodied carbon of a sustainable interior also becomes more relevant.
Common interior finish materials such as acoustic ceilings, gypsum wall boards, and nylon carpeting can have a considerable impact on a project’s embodied carbon if not assessed from a sustainability perspective as early on as possible in order to account for any budgetary adjustments they might require (McConnell, Mithun).
Summary: Low-carbon sustainable building and interiors material strategies
Reduce fossil fuel energy required for extraction and manufacturing
Choose those that contain high recycled content
Bio-based and carbon sequestering resources
Prioritize rapidly renewable materials
Consider climate-specific durability of materials
Reducing Transportation Emissions in Sustainable Buildings and Interiors
When considering a material’s embodied carbon and its life cycle, transportation emissions can also have a considerable impact meaning we need to look into material supply chains, aim to source locally or regionally, carefully plan construction material deliveries to limit wastage, and choose low-emission transport options whenever possible.
Select materials that are produced from a low carbon system, both through their manufacturing and transportation. The use of local, sustainable materials will greatly reduce transportation distances and emissions, so it is important to understand what is available within an acceptable radius of your project (“Whole Building”).
Sustainable Transportation of materials
In addition, by reducing the number of site deliveries through close coordination of manufacturing and construction timelines we avoid the delivery of materials at inefficient times that in turn can cause damage and unnecessary waste.
Efficient alignment of transportation with project timelines in this way is an essential step to reduce the embodied carbon of a building project (Best Practice).
Finally, whenever possible choose transport options that create the lowest carbon emissions, such as train or barge, when available (“Whole Building”).
Low-Carbon Sustainable Building Transportation Strategies
Choose materials with a low-carbon supply chain
Source locally
Coordinate transport with project timelines
Utilize low-carbon transportation options
Reuse & Recycle Materials
The implementation of salvaged, reused, and recycled materials greatly reduces embodied carbon as it eliminates the need to extract and manufacture new resources. Salvaged materials only involve emissions related to transportation and refabrication, greatly cutting a sustainable building’s overall embodied carbon (“Salvaged Materials”).
Hand-in-hand with the use of salvaged materials comes deconstruction, the process of carefully disassembling a building to save its materials rather than the more common demolition strategy. Examples of easily salvageable materials include brick and wood, as well as steel and precast concrete (“Salvaged Materials”).
If materials cannot be salvaged, choose options that contain high recycled content. Paper, plastic, and glass products are increasingly common in building materials and provide greener options for projects aiming to lower their embodied carbon.
Sustainable Building Material Reuse Strategies
Salvage materials from previous builds
Implement deconstruction
Utilize materials with high recycled content
Helpful Embodied Carbon Tools
With all of these strategies, it is imperative to first set project carbon goals. As with all sustainable building projects, the use of benchmarking is essential to determine what has been done before and what is plausible for any given project. Within each development, stakeholders involved in the design and construction process will benefit of how their role can positive (or negatively) impact the embodied carbon of the project (“Whole Building”).
Early on in the design process, various tools can be used by team members to determine the potential carbon outputs. For example, the programs Revit and Tally can work together to store information about material quantities and qualities to pre-form LCAs and determine the carbon impacts of building materials. Tally currently contains more structural, heavy material data but is moving towards containing more interior material information such as for furniture and casework.
When considering which materials to utilize, look for those with Environmental Product Declarations (EPDs) - effectively a way of communicating information on a material’s environmental impact. This information can be found online in places such as the EPD library. In addition, the Carbon Smart Materials Palette provides information on high and low impact materials over their life cycles.
Finally, there are several free carbon calculators that can be used to compare material options. EC3 is one of the most common in the industry, allowing users to compare construction materials and review material EPDs.
Pathfinder meanwhile is a carbon calculator that focuses more on landscaping elements, even including estimates for natural features such as trees and greenery.
How to Reach Embodied Carbon Goals for a sustainable building
Set embodied carbon goals early on in the design timeline
Ensure collaboration across project team, aligned behind sustainable building interior strategies
Incorporate design and LCA tools (Revit and Tally) to track data on embodied carbon in materials
Use online resources or consultants to identify low-carbon material solutions
Use online carbon calculators for complete transparency
Sources
“ Best Practice Guide to Improving Waste Management on Construction Sites.” Resource Efficient Scotland, Scotland.
Isaac, Philip, and Jonny Hawkshaw. Elsevier, 2020, Scaling Low-Carbon Construction Materials, thestructuralengineer.org. Accessed 5 May 2022.
McConnell, Claire, et al. “A Year of Embodied Carbon.” Mithun, 5 Nov. 2021, https://mithun.com/2021/11/05/a-year-of-embodied-carbon/
McConnell, Claire. “Greenbuild.” Greenbuild, Greenbuild International Conference & Expo, 22 Sept. 2021, https://informaconnect.com/greenbuild/agenda-2021/ Accessed 5 May 2022.
“Salvaged Materials.” SE2050, SE 2050, https://se2050.org/resources-overview/strategies/salvaged-materials/
“Whole Building Approaches to Emissions Reductions.” Carbon Smart Materials Palette, Architecture 2030 - Enfold WordPress , https://materialspalette.org/whole-building/