How carbon footprint calculators help architects achieve sustainability through design

A rendering of the new headquarters of the Swedish company Ecohelix.
The sustainable design of the new headquarters of Swedish company Echohelix has been optimized using Sweco’s carbon cost compass. Image courtesy of Suico.
  • There is a high demand for better methods for calculating a building’s embodied carbon.
  • Calculating embodied carbon has traditionally been time-consuming and complex. Now a new generation of software tools is simplifying the task, enabling architects and general contractors to make more informed trade-offs between carbon emissions and a host of other factors.
  • It is becoming easier to predict the environmental impact of design decisions in the early stages. The results can be impressive, with one new corporate headquarters project reducing embodied carbon by more than 50%.

When Swedish biotechnology and green building materials company Ecohelix set out to build a new factory, it wanted to reduce environmental impact in line with its sustainability mission. The company specializes in wood components, and since the new building will be located in a forest, the company wanted its carbon footprint to be minimal.

In a numbers-focused architecture, engineering and construction industry, carbon outcomes must be quantified. Ecohelix wanted to know from the beginning what the true carbon footprint of the new facility was. “We produce a wood-based product that has a positive impact on the total carbon footprint of a given building value chain,” says Oscar Schmidt, Chief Technology Officer at Ecohelix. “When it comes to our large-scale plant, we want the most sustainable, practically and economically feasible building materials.”

Ecohelix approached architects at Sweco, one of Europe’s largest architectural and engineering consultancies, to add carbon cost forecasts to their initial designs using Sweco’s in-house solution, Carbon Cost Compass, or C3. C3 is part of an emerging class of software tools that help architects and engineers simplify the arduous process of balancing trade-offs between a structure’s carbon footprint and costs while many design and material options are still on the table.

Architects use a carbon calculator on a computer screen.
Architects work using Sweco’s Cost of Carbon Compass, or C3. Courtesy of Suico.

Most carbon calculators focus on the embodied carbon of specific building materials, or show the cost of operating a structure after its doors are open. Few can go deeper into considering the impact of supply chain options and a building’s end-of-life plan.

If you don’t measure it, you can’t manage it

AEC is one of the worst offenders when it comes to greenhouse gas emissions. A recent UN report concluded that energy consumption and CO2 emissions in the sector reached a new all-time high in 2021, accounting for 37% of global energy and process-related CO2 emissions. This is 2% higher than the previous peak recorded in 2019.

With 230 billion square meters (PDF, p. 4) of new buildings planned by 2060, emissions associated with industry’s embodied carbon consumption will continue to rise if something does not change. Carbon calculators can impact the way buildings are constructed by providing designers with the data and insights they need to inform strategic choices about carbon impacts and costs from the early stages of site planning through operations.

In the past, this calculation was mainly done on spreadsheets after capturing a lot of data. After performing detailed calculations, arriving at the final forecast took time and resources. Depending on the design stage and availability of details on construction engineering and materials, it may take longer. If any changes were made, the numbers had to be run again.

With the right software, this process can be reduced to a few clicks. In minutes, not days, architects and engineers can see how different designs – and any subsequent changes – will impact the sustainability of the project.

The best carbon calculators take accurate carbon impact data and ensure they adhere to the architectural design paradigm from the early stages. Users can visualize the carbon and cost impacts of design changes in real-time, and make informed decisions that balance sustainability and business outcomes.

Looking across the life cycle

The use cases for each carbon calculator tend to relate to specific stages in the building life cycle. Below are some options that give a quick overview of what is currently available. The following solutions work seamlessly with BIM data. To find more embodied carbon accounting tools, the non-profit Carbon Leadership Forum (CLF) offers this helpful resource.

Early concept stage

When preliminary drawings are executed and the final engineering of the structure is completed, EHDD Engineers’ EPIC tool can calculate expected embodied carbon costs. When information about materials and dimensions is limited, EPIC uses c.scale carbon accounting methodology to make a preliminary design and relies on industry data to arrive at approximate carbon emissions. Sweco’s C3 is also effective at the early concept stage. With C3, it is possible to compare different solutions and quickly find the best climate and budget options. It is already used by Ecohelix and others to calculate carbon emissions and construction costs.

EHDD's EPIC tool, which appears on a computer screen, can calculate expected embodied carbon costs.
EHDD’s EPIC tool can calculate expected embodied carbon costs. Courtesy of EHDD.

Detailed design stage

Later in the process, when there is enough detail about the building geometry and materials to create a full BIM model, Sweco’s C3, tallyCAT (see below) and Autodesk Insight: Carbon Insights are useful tools. Carbon Insights (currently a Tech Preview) can be used to perform “cradle to gate” analyzes of exterior building walls and windows directly within Autodesk Revit. It provides useful insights into the carbon impact of different materials from raw material extraction to the manufacturing process.

Late design stage

The Construction Embodied Carbon (EC3) Calculator is a free tool from Building Transparency. Now integrated with another free option called Tally Climate Action Tool, or TallyCAT, the combined platform allows architects, engineers and clients to conduct deep analysis of the embodied and operational carbon costs of a completed building design. It can also provide a calculation of the carbon cost embedded in the supply chain of the materials chosen for the building.

The computer screen displays the data used in the Building Embodied Carbon Calculator.
TallyCat now integrates the Construction Embodied Carbon (EC3) Calculator.

Full spectrum analysis

The One Click LCA Calculator allows architects to go ahead and calculate the initial impacts of their designs. It covers the full expected life cycle of a building – including its demolition and eventual disposal – and helps architects conduct careful analysis to optimize the design process and meet certification standards for low carbon building solutions.

Carbon calculators in action

When American flooring company Interface envisioned its new headquarters in downtown Atlanta, initial plans called for a 70,000-square-foot building. After analyzing its design using EC3 (PDF, p. 8), the company’s architects realized they could achieve the same goals with a 40,000-square-foot building.

By implementing flexible seating and “hot desking,” the overall use of space has improved dramatically. The architects then analyzed two options with EC3: a new 40,000-square-foot building versus renovating a 1960s-era, 40,000-square-foot building downtown.

Interface chose the second option and found that renovating and reusing bricks from an existing building would reduce embodied carbon by 50.48% (PDF, p. 9), while also reducing the overall building impact (including parking) by 42%.

Sustainability from the beginning

Although accurately measuring sustainability has been on the AEC agenda for years, its complexity, competing models, and disagreement over standards have all contributed to a lack of transparency in carbon accounting tools and practices. As carbon cost calculators improve and mature, the hope is that architects and clients will be able to modernize processes and achieve accurate and impactful results.

“There is a very strong synergy between the carbon costs and the hard costs of different building materials in the early stages of a project,” says Mathias Nall, Digital Development Leader at Sweco. “The decisions you make around sustainability and materials will give you greater success.” Control – if you do it early.

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