Last month at Facades+ San Francisco, hosted by AN in collaboration with EHDD, a roundtable convened Foster + Partners senior partner and designer Ben Dobbin; University Of California, Berkeley director of communications David Lehrer; Turner Construction Company sustainability manager Brett Stuckey; and Skanska sustainability director Tolga Tutar. The discussion, moderated by EHDD principal Quyen Luong, focused on the gap between design intent and built reality in the construction of low-carbon envelopes. Across back-to-back mini-presentations followed by a Q&A, the speakers discussed dematerialization, building typologies, adaptive reuse, and the early integration of sustainability in design conversations as areas of focus for further improvement in the creation of low-carbon facades.
Ben Dobbin: “What is the essential minimum requirement that you need to construct a habitat?”
Dobbin stressed that material choice is vital to construction. The selection process should be informed by the performative elements and function of the building, while also adhering to climate regulations and carbon efficiency He emphasized harnessing the unique advantages of materials, such as glass and timber, to do more with less. It is in the weight, type, and capacity of what is used that the answer to low-carbon facade construction is found. “For smaller scale projects,” he said, “there is no reason we have to rely entirely on aluminum facades for code.”
David Lehrer: “Going forward, embodied carbon emissions must be a higher consideration in project selection.”
Lehrer spoke about the research he did with Center for the Built Environment (CBE) on creating a taxonomy of the practical elements that compose a low-carbon facade. He noted that finding operational data on the carbon efficiency of existing buildings was difficult. Lehrer made use of technology such as VR to place subjects in spaces with varying degrees of view quality. View quality, he argued, and carbon footprint were related through the facade itself, as inhabitants of a building have certain standards and preferences for what they can observe through the facade. A fully glazed facade requires mitigation of some sort, perhaps through extra layers of glass or extra shading, all elements which would have an impact on the carbon footprint of the building. At what point, Lehrer asked, could an optimal balance be achieved?
Brett Stuckey: “Don’t assume that sustainability is making its way into design conversations.”
Stuckey asserted the importance of addressing concerns of sustainability early in the design process, considering methods of transport for construction materials or the procedure required to clean the facade—often overlooked in the question of carbon efficiency. Stuckey described the successful introduction of monthly sustainability check-ins into the pre-construction and construction process, where questions were raised about operational emissions and dematerialization. It is in the early stages of project development, he reiterated, in conversations between designers and contractors, that solutions for carbon-conscious building can be found.
Tulga Tutar: “The buildings with the lowest emitted carbon footprint are the ones we already have, and the materials with the lowest carbon footprint are the ones we don’t need in the first place.”
Tutar identified facades as the most critical asset of managing climate and financial risk and quality at all stages of a building’s lifespan. Operational emissions, embodied carbon emissions, and, critically, the potential of a facade to be repurposed or recycled, are all considerations which can lower the cost of a building. He argued that a more efficient facade resulted in less risk to MEP systems and played a crucial role in transitioning the existing building stack. The most carbon efficient practice, then, is to create structures that can be repurposed with a minimal amount of carbon byproduct. Tulga concluded with the notion that “it’s really important to treat carbon as a new currency.”
Q&A Highlights
Quyen Luong (QL): Why don’t we go to the experience versus performance gap. How do we translate high-performance metrics into palpable human experience that bridges the gap between design and lived experience?
Ben Dobbin (BD): We always want to take the performative elements of a building and use it as a tool for expression and architecture. One of the projects is Maggie’s Center, where people suffering from cancer can speak to other people with similar problems. It’s adjacent to a very sterile hospital. The environment is defined by engineered trusses. This is a timber structure which is lightweight and takes lessons from early aeroplane design which creates a modified improved truss. A lot of analysis went into removing material from this truss. A lot of carbon content in the facade is in the support structures, in what holds the facade up. This design incorporates that concept in its spirit. The softness of the wood is biophilic and warming and soothing. We borrow from another technology and another discipline and it informs our architecture. You can transpose these thoughts onto the structure of a facade and start to think laterally. There’s a lot of building typologies where we can go all out on renewable materials before we even start talking about recycled materials for the other components. It’s really thinking about how those materials enrich the architecture.
QL: How do we evaluate the tension between what we need from a facade to have an alluring viewing experience and the reality of carbon emissions in construction?
David Lehrer (DL): One of the research trends we’re talking about is that CBE is now looking at view quality. There’s research showing that view can have a positive impact on students and patients in hospitals, especially when you have views of green spaces. With a group of collaborators around the world, we’ve begun developing symmetrics for measuring and designating what a good view is. There are really three components: The content of what you’re seeing—are you seeing nature, are you seeing distant views, are you seeing movement—the access to what you’re seeing—how far away are the windows to where you’re sitting, how wide are the windows—and lastly clarity. If there’s glare or the shades are dropped all day you’re not getting the benefit of view. A study done using VR to expand the range of glazing for the subjects found that as the angle of view increased the subjects enjoyed the view more. But it reached a maximum of around 65 percent of the window-wall area, and after that it didn’t seem to benefit the subjects a whole lot more. There’s an ongoing debate about how much glazing we need, and at what point is it optimal? If we have a fully glazed facade and we’re mitigating the impacts of that with extra layers of glass and extra shading, we’re increasing the footprint of the embodied carbon. Maybe then there’s a balance point for the amount of glazing.
QL: What does engagement from a contractor perspective really mean when we talk about strategies for an effective low carbon design?
Brett Stuckey (BS): One of things we’ve done recently at Turner is incorporate this very key line item into the scope of our work, to say that you will during pre-construction host a monthly sustainability meeting where we talk about sustainability and how it relates to the facade. The agenda for us has been number one to minimize embodied carbon and hopefully maximize recycled content. Where are you going to source your materials from and what are those percentages we’re looking for? What is the timeline that they would give us to produce an EPD? What’s your transportation strategy? If you’re trucking, for example, are you using renewable diesel to transport materials? These meetings give us an opportunity to ask what seem like simple questions but are ones that are often never brought up. What about deconstruction? If you’re in the sustainability and deconstruction world you are continually finding challenges with facades and glazing. If the caulking has PCBs or asbestos you have to throw the whole facade away. What we’re going to do is learn and make sure we’re designing so the facade can be carefully deconstructed. I’ve seen a lot of success in these meetings after hard questions were asked.
QL: Tolga, you said that envelopes are the first line when we’re looking at low-carbon design in general, because it separates the environment or allows the environment to come through. Could you talk about that?
Tolga Tutar (TT): Facades are really the first line of defense. I’ve been excited to see them evolve from aesthetic curb appeal and basic protection to a critical component of energy efficiency and recognized as the most critical asset to manage climate and financial risk and quality. There are different issues we identified as to what low-carbon really is and how those adjustments interact with other building systems. If you just isolate facades, they are considered a passive component of the building, but they actually have a very dynamic relationship with MEP systems.When you optimize the facade system, it has different emitted carbon impacts. Maybe you are evaluating a single-skin versus double-skin facade. If you’re just looking at this problem on a facade level, a double-skin facade has more emitted carbon because more materials equals more emitted carbon, but what’s the impact on the building level? By optimizing the MEP system with the facade you can then downsize the mechanical system, which means less materials for the MEP system, which would mean less refrigerants and higher energy efficiency. Refrigerant leaks also have a very high carbon footprint. Maybe you can optimize the facade system to reduce transportation or construction emissions for contractors with more prefabricated modular systems that can be installed in a short time. What about end of life emissions? Can you design building assemblies that are easy to deconstruct at the end of their lifespan or ones that can be replaced quickly for maintenance? All of this is part of low-emitted carbon facades. We have to think about this problem beyond operational carbon or emitted carbon just on the facade level and more on the level of the building.
QL: What are the biggest barriers as an industry to high performance low carbon facades on all projects?
BD: One of the difficulties is the location of where things are made in relation to the location of where things are being built. You can see that in our area here. People want to build very large buildings here and some of the capabilities for that just don’t exist, even within 500 miles. For some elements, yes, but for some high-performance materials, no. A greater distribution of some of those capabilities in the industry would help. As architects, we also have to adapt to what you can get in the locality as well.
QL: Any thoughts from the contractor side?
BS: Cost is a real factor. Working early with the design teams and the client to understand the goals and then going through a target value design process to ideally get to those goals is something we can implement on a regular basis.
TT: The biggest barrier is the artificial perception that sustainable products cost more. Novel products coming into the market, yes, there’s an R&D cost, but the most impactful carbon reduction strategies are the simple things: Dematerialization. Finding a robust, pure design will help to reduce material quantities, because the buildings with the lowest emitted carbon footprint are the ones we already have, and the materials with the lowest carbon footprint are the ones that we don’t need in the first place. Finding those opportunities and complementing those with novel low-carbon or carbon-negative products is the best strategy.
→ Continue reading at The Architect's Newspaper
