While "counting carbon" might seem intimidating, it's more straightforward than it appears. There are established processes that are easy to follow, and they make a big difference in addressing climate impact.
In this updated article, we’ll share what we’ve learned to encourage others to use these tools and reduce carbon emissions.
Choosing the Right Guide
Before you start, you’ll need a good guideline. We recommend the Institution of Structural Engineers' (IStructE) "How to Calculate Embodied Carbon", a free and globally recognized resource available on their website. Download the guide here.
This guide outlines a straightforward process to quantify carbon emissions through the lifecycle of materials.
For calculations, the Structural Carbon Tool spreadsheet is a simple and effective option. It’s also free and available alongside the guide: Download the tool here.
Using this tool, you can account for the environmental impact of a project by multiplying material quantities by their respective carbon factors across different lifecycle stages.
Breaking Down the Life Cycle Stages
To measure embodied carbon, a building's life cycle is split into stages, each representing a unique source of carbon emissions:
1. Product Stage (Modules A1–A3):
Includes emissions from material extraction, processing, and manufacturing.
Covers transportation between processes and up to the factory gate.
Factors in recycled content that influence emission levels.
2. Construction Stage (Modules A4–A5):
Emissions from transporting materials to the site.
Includes energy use on-site and waste management.
3. Use Stage (Modules B1–B7):
Emissions related to building operation, maintenance, and eventual refurbishment or replacement.
Focus is often placed on Module B4, addressing material replacements during the lifecycle.
4. End-of-Life Stage (Modules C1–C4):
Emissions from demolition, transportation of waste, and disposal.
5. Beyond Lifecycle (Module D):
Considers the environmental benefits of recycling, reuse, and energy recovery from materials.
Where to Start?
As a minimum scope, your calculation should include Modules A1-A5 for primary building and superstructure elements.
The reasons for this are that these elements are perhaps the most readily understood and quantified and that emissions within these modules typically make up to 50% of the total lifecycle value, so they should be the focus of our carbon reduction efforts.
How to Calculate
The process is simple:
Determine the volume of each material (from BIM models or manual estimates).
Multiply the volume by its carbon factor (available in published emission tables).
Standard materials such as timber, steel, aluminium, glass, etc., have readily available published emission data, but how do you calculate the emission of, say, an air handling unit or specific tensile fabric?
For products without standard data, Environmental Product Declarations (EPDs) can be requested from manufacturers, suppliers or sourced from online databases.
The process of engaging with your supply chain to quantify such EPDs is a positive sustainability consideration in itself – it heightens awareness of sustainability responsibilities and encourages openness and innovation discussions within the supply chain.
Transportation Emissions
Another insightful aspect of carbon accounting is assigning emissions to global material transport. Here, Google Earth is our friend, and we can map the freight distances by air, sea, road, etc., and the Structural Carbon Tool can assign a carbon cost to transportation both at the manufacture (A1) and installation stages (A5).
Making the Data Meaningful
So, you have a workflow in place now that allows us to calculate the tons of carbon emitted by your building or scheme during the various stages of its life, but what does that number mean? What do you do with it?
The key here is not to focus on the number itself but on the magnitude of difference between numbers for one scheme and another.
You can use the data to:
Identify materials with the highest carbon contributions. By recognizing these high-impact materials, you can prioritize initiatives focused on minimizing their usage or finding / developing greener substitutes.
Explore alternatives, like recycled materials or more efficient designs. Additionally, innovative design strategies that improve efficiency—such as modular construction or designs that reduce material waste—can also contribute to lower carbon numbers. By considering the entire lifecycle impact, it becomes possible to make informed choices that lead to substantial reductions in emissions.
Evaluate different materials and conduct a comprehensive comparison, including carbon storage capabilities, durability, and end-of-life processing, to help guide better purchasing decisions.
Tracking Progress
It is important to track your reductions in carbon emissions over time.
IStructE and RIBA (Royal Institute of British Architects) have established goals for reducing the embodied carbon in buildings using their 'SCORS' rating (Structural Carbon Rating Scheme). The rating considers the equivalent carbon emissions during the entire building process, from the "cradle to construction."
The assessment focuses on the structural components of the building envelope only. It then estimates the carbon footprint of architectural features, fixtures, finishes, etc.
According to a 2020 study of all building types designed by 276 consultancy practices in the UK, the average SCORS rating was assessed at 'E' (360kgCO/m²).
As a result, yearly design improvement targets have been set to achieve carbon neutrality by 2050.
For example, we have completed our carbon accounting assessment of our two primary product offerings: our safari camp canvas walled Expedition Camps tents and our premium hard-walled insulated T2 Modular suites.
We find that the Expedition tent achieves a rating of 'A' with emissions of 136 kgCO/m², and the T2 achieves a rating of 'B' at 172 kgCO/m². Given the optimized forms and efficient use of lightweight materials, both ratings sit above the '40% better than average' line.
By plotting your building / structure rating over time, you can see where it sits in relation to that neutrality path and make systematic improvements to maintain this trajectory.
The key takeaway is to embrace the process.
Don’t worry about perfection—what matters is learning, discovering, and improving. Carbon accounting helps us make smarter, more sustainable decisions, and every small step counts.
Tenthouse Structures specializes in the architecture, engineering, supply, and assembly of tensile tented structures. Collaborate with us to bring your project vision to life.
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