Using BIM and Generative Design to meet the MEP 2040 Commitment | Henderson Engineers Using BIM and Generative Design to meet the MEP 2040 Commitment | Henderson Engineers

Using BIM and Generative Design to meet the MEP 2040 Commitment

In addition to our Henderson 2040 Climate Pledge, we recently become a signatory to the MEP 2040 Commitment. Click here to learn more about this recent announcement from our sustainability director, Brian Alessi. This is part of our strategic plan to accomplish our vision of “building a better world” and we are excited to play an active role. Brian would agree that public statements without action are just posturing. Action without progress is just movement. As Alfred Montapert, American engineer and philosopher, said, “Do not confuse motion with progress.”

Efficacy is prioritized over efficiency at the start, but efficiency is needed to increase adoption. Just like any other construction project, building a better world only works if we get it done on schedule. Design tools allow us to make progress because they increase efficiency. Becoming a signatory was our commitment. Leading our commitment and mindset is the challenge Brian accepts. Implementing that challenge into design tools is the challenge I accept.

How did we get from MEP 2040 challenge to design tools?

The MEP 2040 Challenge is an initiative of the Carbon Leadership Forum (CLF) that was announced in advance of the COP26 Cities, Regions & Built Environment Day in Glasgow, Scotland, on October 31, 2021. The CLF also has an initiative for an Embodied Carbon in Construction Calculator (EC3) tool.

The CLF defines the EC3 Tool as a free and easy-to-use tool that allows benchmarking, assessment, and reductions in embodied carbon, focused on the upfront supply chain emissions of construction materials. The EC3 tool was incubated at the Carbon Leadership Forum with input from nearly 50 industry partners and utilizes building material quantities from construction estimates and/or BIM models and a robust database of digital, third-party verified Environmental Product Declarations (EPDs).

Utilizing this data, both the design and procurement phases of construction projects can benefit from the EC3 tool. This can include evaluation of a project’s overall embodied carbon emissions and enabling the specification and procurement of the low carbon options. Using the openEPD open data format, this is the tool that is setup for long-term success as a reliable and accessible EPD database.

The EC3 tool is free, cloud-based, and easy to use. Those are some of my favorite qualities of software but there’s one thing missing. Integration into BIM is at the top of my favorites list. True integration into BIM means integration into the BIM workflow and its primary design tools (Autodesk Revit in our case). It’s not simply a one-way export from Revit to csv. Another helpful attribute is software with an API. The EC3 tool has a documented OpenAPI 3.0 compliant RESTful API. That allows us the ability to create our own tool but that would be quite the undertaking. Thankfully, Building Transparency has just released the Tally Climate Action Tool (tallyCAT) Public Beta that precisely fulfills our need for integration into Autodesk Revit. According to Building Transparency, tallyCAT is a free and open-access Revit plug-in that supports the export of material quantities from Revit to EC3 and allows synchronization between them. Powered by the EC3 database, it enables users to select materials based on project needs, assess embodied carbon reduction opportunities, and produce charts and reports from within Revit.

What are we going to do with EPDs?

We have big plans for incorporating EPDs into our standard design approach. Specifically related to BIM, we plan to integrate generative design with embodied carbon and operational carbon. The automation and algorithms are dependent on one key component. That component is the EPDs from the manufacturers. The math and automation are the same, but the EPD can only come from the manufacturer. We can automate the placement of component A vs component B just as easily, but that automation will be built on the selection based on criteria.

The starting point in available data that we have for structural and architectural allows us to prove the concept that automation can be done efficiently with embodied carbon as a metric. This is simply one part of the criteria to consider in design along with others such as cost, lead time, performance, etc. The goal of generative design is to get to higher quality decisions more efficiently. Early decisions on projects have lasting impacts. It is our goal to bring embodied carbon into those early conversations where decisions are made. We not only want to talk about embodied carbon but also be able to bring context by quickly performing generative design studies where we can review real results. We plan to extend generative design to also include operational carbon and energy modeling. Stay tuned for more on that topic.

What’s standing in our way?

There lacks a critical mass of EPDs for components, equipment, and materials of the building systems we design. There isn’t even a reasonable population of EPDs to refine the automation around. The MEP 2040 Challenge signatories commit to asking for EPDs of the components we design. The structural and architectural components are there because they were a requirement of a project. The TallyCAT add-in doesn’t even export the building systems elements. The tool only exports structural and architectural components. Requirements drive change. We are hopeful that the commitment to ask for voluntary compliance will drive change fast enough.

Why are building systems missing a reasonable population? Does the industry favor architects and structural over building systems? Maybe. Is that a conspiracy to keep building systems behind on embodied carbon? Probably not. Simply put, EPDs for building systems components are hard, which is why there are not more of them. These components consist of many materials and subcomponents, from all over the world, making it difficult to provide accurate accounting. An EPD accepts nothing less than accurate accounting. Concrete has fewer and easier to track materials than an air handler unit. There is also more concrete on projects than air handler units, which makes it a larger target for reduction in embodied carbon because the impact would be greater for even a minor change. According to Brian Alessi, “It’s not unusual for around 75% of embodied carbon in a project to be a result of concrete and steel alone. The industry started chipping away at these two big ticket items first. Now we’re seeing work being done on other components like MEP.”

Should we wait on EPDs or guess?

Both. We are asking for EPDs as part of our commitment. We will also forge ahead preparing our tools and workflows with the anticipation that we will have a dataset large enough in the future. We must be transparent about the successes and limitations we encounter along our journey. In a recent article, I covered our updated generative design tools for our duct module. We have enhanced the functionality of that tool to include embodied carbon units as a metric. We don’t have an EPD for our duct module just yet. How did we put data into a generative design tool used to make design decisions on real world projects? We guessed. It was an educated guess but still an estimate at best.

Accompanying the lack of EPDs for building systems is a lack of data for embodied carbon of the common materials used in the components. The duct module is made of sheet metal. It is the same sheet metal that is used to stick build duct so there is nothing special about the metal itself. The duct module is designed to reduce waste, which reduces the embodied carbon footprint, but the metal is the same. We had very little success in finding data on embodied carbon for common sheet metal. The closest data we found was from an EPD for folded circular ventilation ducts made of galvanized steel from Lindab AS in Norway. The declared unit has a GWP total of 1.97924 kg CO2e with the product options of 1 meter long, 125 mm diameter, and a 0.45 mm wall thickness. The following is the math used to transfer that to GWP total/square inch.



We used the 0.0032518 kgCO2e/in2 and applied that to the surface area of the components used then the duct module design methods. This included the main modules as well as the main elbows, runout modules, and runout elbows. This resulted in an estimated GWP total per unit. That unit load was defined in a centrally located JSON file used by the generative design add-in. This approach allows us to update it with new (more accurate) values over time and the new layouts immediately benefit. Once the official EPD is available, we already have the tool and workflow built.

You may be thinking that we could have simply used linear feet or square inches of material and built the tool around that to achieve the same result. However, we would not receive the benefit of introducing our design staff to using embodied carbon as a consideration in design now instead of waiting. Putting a carbon unit in the dialog in front of the designer making a design decision makes it a focal point. This is simply a starting point and not the result. This data also allows us to look at all our ductwork across projects. Incorporating some data analysis with our project database allows us to see the typical sheet metal per project of a specific project type and size. This can tell us the sheet metal we’re saving with a reasonable estimate of the embodied carbon that goes along with it. Isolating the decisions so they can be analyzed and automated is the whole point of integrating embodied carbon into design tools. This is not only motion but progress.


Building Transparency:

Carbon Leadership Forum:

Written By

BIM/VDC Director


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