In 2019, Clark Nexsen’s Don Kranbuehl, FAIA, LEED AP, attended the AIA Large Firm Roundtable Summit on Carbon and left with a strong feeling that building design must change in a big way. The built environment accounts for almost 40% of CO2 emissions globally – meaning architects, engineers, and facility owners have the opportunity to substantially reduce human impact on the environment and slow the rate of climate change. In the following, Don and Julia Janaro, AIA, LEED AP, WELL AP, present the urgent need for low carbon design as well as tools and case studies for achieving sustainability goals:
Why focus on carbon?
Global carbon emissions have been increasing dramatically for the last 150 to 200 years. Scientists tell us we have about 10 years to make a critical, substantial change and get carbon emissions under control. This is why 2030 is highlighted so frequently in sustainability goals for the AEC industry, and why embodied carbon deserves a growing share of attention. The Paris Agreement presented the following central goals:
- Reach peak CO2 by 2020
- Reduce carbon emissions by 50% by 2030
- Reach zero emissions by 2050
We are racing against rising temperatures that could irrevocably alter our world. Exceeding a 1.5 degree Celsius increase in average global temperature could be catastrophic, and the following graphic shows us the anticipated rise in average global temperature if we take several different courses of action:
The “business as usual” line shows us blowing by an 8 degree increase by the year 2200, and several lines with emissions peaking in the decades to come show devastating increases. Playing our part to level off this curve is an ethical imperative for the design industry.
The opportunity to change this trajectory is there. By 2060, the global building stock is expected to double, and 40% of this construction is expected in the next 15 years. Reducing embodied and operational carbon in these facilities is a must.
While operational carbon rises over time, embodied carbon impacts are immediate and much greater. Only 28% of the total carbon emissions from buildings in the next 10 years will be operational. Looking at this type of data can feel overwhelming, so it’s better to start small and think of each design choice incrementally. We’re essentially counting calories, and we need to make healthier decisions.
Tools for reducing carbon
The good news is there are a variety of tools to help designers count carbon and make evaluating material choices easier. Each tool has its place depending on where the project is in the design process, the type of project, its location, and other factors. Some are better suited to advance planning, while others are invaluable during construction and post occupancy.
The graphic above illustrates our integrative design process and where we use which tools along that timeline. For example, Tally and Athena are most useful early in the design process as iterative decision making is taking place. EC3 is a tool we use as we go through construction documents and construction administration. Tools such as EPD (Environmental Product Declarations) are used to feed into the other software and are resources for material quality, sustainability, and embodied carbon.
- Tally is a Revit plug-in (developed by Kieran Timberlake) that is especially useful for comparing materials or completing total building analysis. We use Tally on virtually every project in early design phases, alongside energy modeling.
- Beacon is a free Revit plug-in (developed by Thornton Tomasseti) that is primarily focused on structural systems.
- Athena is a separate model of the project and is especially useful for transportation projects. It integrates a lot of material data.
- EC3 is a free Revit plug-in by the Building Transparency Group, which focuses more on construction documents and construction optimization.
While software and regulations play an important role in reducing carbon in building projects, common sense approaches still present the biggest opportunity to minimize our impact. The AIA recommends the following practical, straight forward strategies:
- Reuse existing structures
- Limit carbon-sensitive materials
- Choose lower carbon alternatives
- Choose carbon sequestering materials
- Reuse materials
- Use high-recycled content materials
- Maximize structural efficiency
- Use fewer finish materials
- Minimize waste
Overall, these strategies focus on reusing, recycling, and minimizing. Out of an overall building footprint, the amount of concrete and steel is substantial. If a structure can be reused via adaptive reuse or renovation, there is a huge carbon savings.
In thinking about where to spend your time as a design professional, the structure has tremendous impact on carbon footprint, especially embodied carbon. Considering material choices and working closely with structural engineers is key to achieving low carbon outcomes.
Using carbon-reducing tools in practice
The following case studies include a laboratory renovation project for the University of Virginia on their Wise campus and a new lab building for Alamance Community College’s biotechnology programs.
At UVA Wise, we designed an adaptive reuse of Wyllie Hall to create a new home for the school’s growing College of Nursing. The building is an existing, 22,500 square foot concrete structure originally built in 1966 with a wing added in 1996. Its renovation will create instructional nursing and biology labs in addition to a lecture hall, shared spaces, collaborative areas, and faculty offices.
The analyses produced by tools like Tally and EC3 demonstrate why building reuse must be a primary strategy for reducing embodied carbon. Focusing on the structural system and envelope, the Tally analysis shows that the building’s reinforced concrete is the biggest contributor to weight and embodied carbon – and that the savings are huge by reusing the structure. Information like this also plays a role in informing future new building design by showing where to focus efforts (i.e. reducing reinforced concrete) if this were a new structure.
The EC3 analysis is best suited to the construction documents phase. This analysis also shows the opportunity to reduce carbon if we were building new and allows us to roughly estimate a 700 metric ton carbon savings by reusing the structure.
While we aren’t reskinning the building, when looking at any building envelope, we recommend taking a sample size equivalent and analyzing it to inform where the design team should focus on the greatest opportunity to reduce carbon.
The design capitalizes on an existing bump up in the roofline to create a skylight that will highlight and enliven the building’s main entry and stair. The addition of a skylight adds a small amount of embodied carbon, but every impact counts. This is an example of needing to weigh pros and cons in design; ultimately, the added daylight and the positive impact to student well-being took precedence. Wood is used extensively as an interior finish, which adds warmth and offers carbon sequestration properties.
Currently in design, the new Biotechnology Center of Excellence at Alamance Community College will be a premier facility for biotech education in North Carolina. Spanning 33,000 square feet over three floors, this educational lab facility will be a new steel structure with composite deck and a reinforced concrete foundation.
Steel and concrete are major contributors of embodied carbon, but a common challenge to designing low carbon laboratory facilities is meeting programmatic needs without these materials. In this instance, the vibration thresholds required us to select steel and concrete.
There are opportunities to think strategically, with the goal to minimize how much concrete and steel is needed and which products or aggregates are specified. One example is to consider locating higher vibration thresholds on the ground floor or throughout the building. Overall, this is about understanding and considering how programmatic needs impact the final design.
For this project, we wanted to showcase Tally’s ability to look at carbon by line item as well as overall assembly, as shown above. Nuanced analysis helps the design team understand what to prioritize to reduce carbon.
The EC3 analysis shows that there is quite a bit of opportunity to reduce the project’s carbon footprint, using strategies including minimizing the steel and concrete and optimizing the concrete selections.
Successfully achieving zero emissions by 2050 will require architects and engineers to make carbon reduction a seamless aspect of the typical design process. By using these tools and plugging the information in, making it part of each design phase, finding opportunities to reduce embodied and operational carbon will become much more intuitive.
For more information, here is a list of useful carbon resources:
Beacon - An Embodied Carbon feedback tool for Structural Engineers
Climate Earth - EPD library
cove.tool - Machine learning daylight, energy, water and cost simulations
EC3 - Embodied Carbon in Construction Calculator
Tally - LCA plugin for Revit
OneClick LCA - Calculate Environmental Impact (Tally alternative)
Sustainable Minds - LCA/HPD/EPD resource
Climate Positive Design - Design toolkit for landscape design
2030 Carbon Smart Materials Palette - Actions for reducing embodied carbon
Athena Sustainable Materials Institute - LCA resources
eTool - LCA software
BuildCarbonNeutral - Quick Construction Carbon Estimate Calculator
Don and Julia originally presented “Designing Low Carbon Lab Facilities” virtually during the 2020 Lab Design Conference.
Julia Janaro, AIA, LEED AP, WELL AP, is a senior architect who joined Clark Nexsen in 2018 and left the firm in 2021 to pursue other opportunities.