Eight Questions You’ll Hear When Proposing Zero-Carbon Design

And, more importantly, tried-and-true responses from seasoned experts who have fielded these FAQS.

Content used with permission from ARCHITECT Magazine and Architecture 2030. Originally published January 15, 2020.

The time to design carbon-neutral or carbon-positive architecture is now. But change is tough, and any tweaks to design approach, philosophy, or workflow will invariably drum up concerns from your clients or supervisors, and even cause you to doubt yourself. Fortunately, several environmentally oriented designers and firms are eager to help you manage the pushback. Stephanie Carlisle, principal at Philadelphia-based KieranTimberlake; Tenna Florian, AIA, associate partner at San Antonio, Texas-based Lake|Flato Architects; and principal Marsha Maytum, FAIA, principal Bill Leddy, FAIA, associate Gwen Fuertes, AIA, and the rest of the staff at San Francisco-based Leddy Maytum Stacy offer starting points for formulating your own responses to the tough questions you'll invariably face.

Questions to yourself

I'm interested in reducing the embodied energy of my projects, but I don’t have access to materials data, analysis tools, or information on how to conduct a whole building life cycle analysis (LCA). Where can I start?

Leddy Maytum Stacy: Embodied carbon can be a hypertechnical, complex topic, but it doesn’t have to be. Making smart decisions early—such as reusing a building and designing an efficient structure—can provide the biggest “bang for the buck” related to embodied carbon. High volume materials, such as concrete and steel, can account for between 50% and 75% of embodied emissions in a typical ground-up design. When possible, use carbon-sequestering materials such as wood from well-managed forests. Focus on reducing or substituting nonstructural, yet high-impact materials, like aluminum or foam. And look at free educational resources, such as the Architecture 2030 Carbon Smart Materials Palette, AIA Framework for Design Excellence (which now aligns with the AIA COTE Top Ten Toolkit), and webinars available at the Embodied Carbon Network website.

Stephanie Carlisle: The Carbon Leadership Forum recently published an LCA Practice Guide that covers the basics of life cycle concepts, modeling practice, and available tools and databases. The free resource also walks through the steps of creating a whole building LCA model. Tools such as Tally [developed by Carlisle and her firm, KieranTimberlake] and Athena Sustainable Materials Institute's Impact Estimator have online demos and videos that will also take you through the steps of creating your first model and provide pointers for beginners.

Questions from the top

What does "carbon positive" mean? I thought we wanted to be carbon negative.

Tenna Florian: Both terms have been used to refer to buildings that go beyond zero-net-carbon emissions by removing additional carbon dioxide from the atmosphere. When speaking about embodied carbon, we're talking about construction impacts and using building materials—such as wood that is locally sourced from responsibly managed forests—that sequester more carbon than is used by all the other materials for that building. When speaking about operational carbon, we're talking about generating more electricity from renewable sources than needed to run the building.

Of course we care about climate change, but our clients and/or their tenants don't value or understand it. We can’t be selective in choosing our clients.

TF: We shouldn’t assume our clients don’t value or understand climate change. Start by listening to what is important to your clients. Understanding their values informs how you approach the topic of climate change and discuss the benefits of high-performing buildings.

LMS: Clients who are resistant to facing climate change may have other values that dovetail with climate change solutions. Most clients care about their return on investment. In providing information about the business case of high-performance design, ongoing operational cost reduction, health benefits to occupants, reduction of absenteeism, and overall user satisfaction, we can help clients see that the benefits of effective design are also better for the environment. Encouraging clients to respond to climate change can pay off. Our clients often want to be seen as leaders.

SC: If we are going to make progress on reducing the climate impacts of the building sector, we can't wait for special clients or projects. We need to find opportunities to reduce the embodied carbon of every project. As architecture firms increase their own carbon literacy and become more confident with low-carbon strategies, they will be in a far better position to do the slow work of raising awareness and influencing clients. We already do this for topics that we feel are essential, like accessibility or health and safety. Keep in mind, design professionals make many decisions for which we don't ask permission and for which we feel obligated to confidently express our opinions. For example, we don't rely solely on our clients' opinions about code, aesthetics, or user experience.

This project is tight on time and budget. We do not have the resources to conduct additional analyses or to reinvent the wheel here.

TF: We aren’t reinventing the wheel. The tools exist to standardize embodied and operational carbon analysis for every project. The cost of time spent conducting the analysis is minimal compared to the value it brings. As a firm, we can differentiate ourselves with our process—a process that needs to continue evolving along with the tools we have at our disposal.

SC: Start by making use of the excellent and accessible resources that exist for designers new to this topic, such as the 2030 Palette, case studies published by other firms, or trade resources like BuildingGreen. Many simple strategies, such as revising your standard concrete specifications and exploring bio-based materials, can add value to all of your projects.

Additionally, consider ways to build capacity and expertise within your firm that can be used on every project. You might need to invest in training in LCA and low-carbon construction strategies for one project, but those skills should be applicable to all of your future work. Find projects where you can innovate and expand your knowledge base; for the others, be sure to make good use of existing resources and reach out to free forums like the Embodied Carbon Network. The carbon community in architecture is growing, passionate, and collaborative. Ultimately, we need to view embodied carbon as an integral part of good design, similar to how seriously we take code review or lighting analysis.

Questions from clients

Having high-performing buildings is not a part of our organization’s mission, so why should we make the investment?

TF: High-performing buildings can affect an organization at many scales—from individual health and wellness to community. Nearly every organization’s mission touches on at least one of those issues; finding points of overlap is key to starting the conversation about the value of performance. If a client feels like they are being listened to rather than told what they should do, they are more likely to trust you to create a building that broadens the impact of their organization’s mission.

I want to reduce my building's embodied and operational energy, but I can’t afford a zero-net-carbon design. What's the next best thing? What's the low-hanging fruit?

LMS: Achieving site net-zero energy can be daunting, but focusing on energy fundamentals such as passive strategies, reducing heating and cooling loads, and moving toward an all-electric design alone can have an outsize effect on operational energy and carbon. It might be easier to get to zero carbon than you think, especially as renewable electricity options become more prevalent. The “bang for your buck” happens when you reuse existing buildings or design an efficient, low-impact structure. If you have concrete in your design, focus on cement replacement with fly ash and slag. If you’d prefer to start by eliminating just one thing, consider swapping out foam insulation from your specifications for a lower carbon impact product.

What is the cost premium to reduce my project's embodied carbon or improve building performance? These strategies sound expensive.

SC: There is no clear indication that low-carbon construction costs more, just as good and thoughtful design has no inherent cost premium. The most powerful thing you can do is make low-carbon strategies normative, standard, and required. Presenting carbon-reduction strategies as a separate design option or as an alternate only communicates that they are optional, superfluous, and external to design. Who would pay extra in that case?

TF: Understanding first-cost and long-term savings is critical to the success of this project, and for quantifying the value these strategies bring to the project. That said, clients have the opportunity to move the industry—especially with embodied carbon—to understand the value beyond cost.

LMS: The short answer is, “It depends.” Cost is contingent on a variety of factors, such as project type and construction region, as well as the strategies and goals of a specific project. Obviously, this is considering first-cost only. Studies show the savings attributed to high-performance buildings, such as operational energy costs, increased tenant satisfaction and retention, and higher rental rates in some certified green buildings.

As this question relates to embodied carbon, there can certainly be first-cost savings. If a client agrees to reuse an existing building, there is immediate savings on structure and enclosure costs, though there may be life safety or other code requirements required that will have an impact on scope. For new construction, an efficient structural design can provide first-cost savings by reducing material use or the weight of the overall structure, which subsequently can reduce the foundation depth. Some of our structural engineers have made the case that cement replacement—with a higher percentage of ternary concrete mixtures—can actually provide cost savings in our Bay Area economy. Finally, reducing finishes is a straightforward way of reducing embodied carbon: Using structure as an exposed finish, such as a concrete floor or mass-timber ceiling, can both reduce embodied carbon and save money.

Is straying from conventional energy sources and systems a good idea given the unreliability and volatility of the electrical grid and utility providers?

LMS: In Northern California, where our studio is located, many cities have taken steps to phase out fossil-fuel combustion in buildings. Simultaneously, we have witnessed utility companies cutting off power to thousands of customers to reduce wildfire risk—a reaction that seems at odds with an all-electric movement. However, an all-electric infrastructure is the only way to achieve our climate goals. For a clean energy future to work, we will need to invest in a robust electrical distribution system, as well as in microgrids, and shift to green energy generation and localized energy storage. Our policies and infrastructure are moving toward clean, renewable energy. As a result, we have begun advocating all-electric designs to owners.


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