Tuesday, May 30, 2017

Part I: Time Value of Carbon

when you save matters

what you build matters

what you don't build matters more

 by Larry Strain, FAIA


Climate change is time critical. If we continue with business as usual, global temperatures are predicted to rise 2°C above preindustrial times by 2030; this temperature change is widely accepted by the world scientific community as the point at which climate change becomes irreversible and catastrophic, often referred to as the global tipping point. We are about half way there, the climate has warmed by about 1° C. In 2013, the International Panel on Climate Change (IPCC) ran a number of emissions scenarios and only one kept us below 2°C: That scenario had emissions peaking by 2020 and fossil fuels phased out by 2055. When we evaluate emission reduction strategies, there are two things to keep in mind: the amount of reduction, and when it happens. Because emissions are cumulative and because we have a limited amount of time to reduce them, carbon reductions now have more value than carbon reductions in the future. The next couple of decades are critical. This paper focuses on emissions from the built environment and strategies to reduce them, particularly on embodied rather than operating emissions.

Figure 1. Emissions Scenarios
 The following terms are used in this paper:
Carbon, Emissions and Greenhouse Gas emissions are used interchangeably and all refer to Green House Gas emissions (GHG) which are made up of Carbon Dioxide (CO2) and other GHG’s, all of which are expressed as Carbon Dioxide equivalents (CO2e).
Embodied Carbon (eCO2): GHG emissions from materials and construction.
Operating Carbon (oCO2): GHG emissions from building operations — heating, cooling, lighting, plug loads.

The built environment as an end user of fossil fuels is responsible for more emissions than any other sector. These emissions include emissions from building operations, (including electricity generation) and embodied emissions from materials and construction.

While constructing and operating buildings is responsible for almost half of U.S. GHG emissions, it also offers significant opportunities for reducing those emissions. The current gold standard for reducing emissions from buildings is to build new, net zero energy (NZE) buildings — very efficient, buildings powered by renewable energy sources, where the energy generated is equal to the energy needed to operate them. Because we build a lot of buildings, this is a critical piece of getting to a carbon neutral built environment. But there are two problems with relying on this strategy alone — building all of those new buildings will generate a lot of emissions and most building emissions come from less efficient existing buildings.

Figure 2. Consumption by End User Sector
Note: although energy use and GHG emissions are not the same, on a national scale, percentages for energy consumption and GHG emissions from buildings are roughly equivalent.
We need strategies that can produce large savings quickly, and because some reduction strategies result in an initial increase in carbon emissions from materials and construction — we need strategies that can produce net reductions within the next critical 10-30 years. Ultimately, we will need a built environment that is carbon neutral.

Ideally, all new buildings should be net zero energy (and emissions), but once buildings have eliminated operating emissions, two other sources of emissions become more important in the short term:

  1. Embodied emissions from building materials, and construction processes.
  2. Operating emissions from the existing buildings we already have.

NEW BUILDINGS: The importance of embodied carbon emissions (eCO2)

When we started to really pay attention to energy efficiency after the first global energy crisis in the 1970s, we were focused on saving energy, not reducing GHG emissions, and embodied energy and their associated emissions were generally ignored. This was because over a building’s lifespan, typically 75–100 years, embodied emissions only accounted for 10%-20% of a building’s total emissions. But a couple of things have changed since then: GHG emissions have become more critical than energy; and as buildings have become more efficient and operating emissions have dropped, embodied emissions now make up a much larger percentage of total lifetime emissions. Embodied emissions are also important because of when they occur—they are the first emissions from a new building. When a building is constructed—before it starts operating and generating operating emissions—it is already responsible for tons of GHG emissions. And even though the majority of embodied emissions happen once—when the building is constructed—and operating emissions happen over time and are cumulative, the majority of GHG emissions for the first 15 – 20 years of a building’s life will be the embodied emissions from materials and construction. If we succeed in making new buildings net zero energy (NZE), then the only emissions will be the embodied emissions. In the long run, it’s still important that new buildings be NZE, but in the short term we need to focus on reducing embodied emissions.

This is not a simple thing to do. We know how to make NZE buildings, but it is much more difficult to reduce embodied emissions to zero. There are immediate steps we can take—reducing the quantity of the materials in our buildings and selecting materials with lower carbon footprints—but modern, industrial materials generate significant GHG emissions in their production. Ultimately the modern material economy will need to become a carbon neutral material economy. 

Monday, May 1, 2017

McClellan Ranch Preserve Environmental Education Center is Marvin Architects Challenge 2017 Best Commercial Winner

McClellan Ranch Preserve Environmental Education Center | Photo by David Wakely
McClellan Ranch Preserve Environmental Education Center. Photos: David Wakely

 The McClellan Ranch Preserve is located on a ranch dating back to the 1870s that has become a park hosting the City of Cupertino’s environmental education programs. Students gather at the new Environmental Education Center before heading out to the 18 acre park to observe, gather data, and perform experiments.

The new Education Center houses classrooms, exhibits, a library and offices designed to work in concert with the sites historic buildings to shape an outdoor activity for large groups. The building connects directly with the farm setting and careful attention was paid to the unique location and presence of birds living on the preserve. Marvin partnered with Siegel & Strain Architects to specify patterned bird-safe glass for the windows to prevent collision.


Siegel & Strain Architects was recognized as the winner of “Best Commercial” project in Marvin Architects Challenge 2017. The jury praised Siegel & Strain and the design team for the careful thought that went into designing the Education Center so that it fit seamlessly not only into its environment, but complemented the historic buildings already there. The design choices, evident in material selection, colors, and form skillfully connect the new Environmental Education Center to the site. “The expression of the wood rafter tails and patio cover construction is incorporated at the interior by the use of complementary wood windows and doors making this building a clear winner.”

Read the article here.

Tuesday, April 11, 2017

"Carbon Is Us"

The featured image is Siegel & Strain’s work for Bishop O’Dowd High School in Oakland, CA. The Center for Environmental Studies is a net zero energy project. Photo by David Wakely.


A response to William McDonough's new language of carbon.

By Guest Contributors Henry Siegel, FAIA and Larry Strain, FAIA
published in The Urbanist on April 4, 2017

“We’re made of star stuff.” –Carl Sagan

“We are stardust.” –Joni Mitchell

Carl and Joni got it right. So does William McDonough when he says that carbon is not the enemy (“Carbon is Not the Enemy,” in the journal Nature in November and referenced in Blaire Brownell’s “William McDonough Reconsiders Carbon and Its Misuse,” in Architect the same month). Carbon is, after all, a basic component of all life on this planet. His “new language of carbon”—distinguishing between fugitive, durable, and living carbon—challenges us to rethink what carbon is and how we might work with it differently. McDonough correctly points out that carbon negative is a positive and we should start calling it that. (Fugitive is an interesting word choice for unwanted carbon. The first definition of fugitive—“a person or thing that has escaped”—makes sense. The second definition—“fleeting and quick to disappear”—is, unfortunately, not the case for atmospheric “fugitive” carbon.)

He is also correct to call out carbon offsets. We need to plant trees and convert fugitive carbon to living and durable carbon, but not as a justification to continue making more fugitive carbon. Finally, he sets the bar at the top: “Just stop it. Don’t offset it. Carbon dioxide in the atmosphere is like lead in a river, right? You don’t put lead in rivers. You don’t start saying, ‘I’m going to reduce my lead in the river by 20 percent.’ You stop it.

New buildings, he says, should all aspire to bring forth “a delightfully diverse, safe, healthy and just world with clean air, water, soil and power.” Who wouldn’t want that? Architects have made progress, but we still fall short of this goal and thinking only about new buildings is part of the problem.

We cannot build our way out of the global warming crisis by relying only on new cutting-edge green buildings. Most of the emissions from the built environment come from operating existing buildings, so one important strategy is to upgrade and reuse existing buildings—and build fewer new buildings.
Reuse recycles the durable carbon that is tied up in building materials and reduces the need for constructing new buildings and manufacturing of new materials with their associated fugitive emissions. Efficiency upgrades, powered by renewables, reduce fugitive carbon emissions from operating our existing and inefficient buildings. 

Another important strategy is reducing embodied carbon—the carbon dioxide emitted during the manufacture, transport, and assembly of building materials. Carbon emissions have a time value; embodied carbon is front end loaded: It ends when the building is occupied (except for upkeep), while operating energy starts with occupancy and continues at a steady rate throughout the life of the building. As buildings use less and less energy to operate, carbon emissions embodied in building materials and construction become a larger part of the fugitive carbon equation. Over the next 20 years—the critical period for reducing the adverse effects of climate change—embodied carbon will be responsible for most new building emissions. 

The built environment is, as we all know by now, responsible for 40 to 50 percent of “fugitive” carbon emissions. What’s missing in McDonough’s redefinition is the sense of urgency required to really act on climate change, since we are on track to hit a global tipping point in the next 10 to 20 years. Given that timeline, we need to do everything we can. Actually, less bad is good.

We can’t wait for the economy to be reinvented. We don’t have a century to get to carbon positive. We need large reductions in carbon emissions now. By all means, let’s encourage and hasten transformational, paradigm-shifting change. But we also need incremental, obvious, “we already know how to do this,” change right now.

Read the article on The Urbanist website.

Friday, March 31, 2017

Ten steps to reducing embodied carbon

By taking these steps upfront, architects can make a big impact during the building stage of a project

By Larry Strain, FAIA, March 29, 2017 

Ten steps to reducing embodied carbon
The early stages of construction for a net zero, low-carbon, LEED Platinum school project,
designed by Siegel & Strain Architects.

The need for sustainability in the design, construction, and operation of buildings is a reality. According to the Energy Information Administration, about 40 percent of the energy consumed in the United States in 2015 went directly or indirectly to operating buildings.

When you add embodied carbon—the energy and emissions from materials and construction—that number is almost 50 percent. As architects, we have the ability and responsibility to provide solutions that minimize the climate impact of the structures we design. And while practices to reduce operating impacts are widespread, less well understood are the carbon impacts during the building stage of a project.

My own “a-ha” moment on this front was when my firm calculated all the embodied carbon emitted from building the Portola Valley Town Center. It’s a very efficient project and has performed better than expected, but when we ran all the numbers we found that construction still emitted 1,000 tons of carbon—roughly the same as 10 years of operating emissions.

The good news is there are several steps architects can take to make significant upfront impacts in the design and construction process.

Reuse buildings instead of constructing new ones. Renovation and reuse projects typically save between 50 and 75 percent of the embodied carbon emissions compared to constructing a new building. This is especially true if the foundations and structure are preserved, since most embodied carbon resides there. With many projects, the first question should be, "Is there an existing building we can use instead?" This is an admittedly hard sell for architects—after all, many of us got into the business for the excitement and challenge of designing something new from the ground up. But channeling that energy and creativity toward making poor-performing buildings into something beautiful, sustainable and energy efficient has its own rewards, and yields substantial positive benefits.

Specify low-carbon concrete mixes. Even though emissions per ton are not relatively high, its weight and prevalence usually make concrete the biggest source of embodied carbon in virtually any project. The solution? Work with your structural engineers to design lower carbon concrete mixes by using fly ash, slag, calcined clays, or even lower-strength concrete where feasible. Though access to these materials varies across the country, with an increasing number of options there is almost always something that can reduce the carbon footprint of your concrete mix.

Limit carbon-intensive materials. For products with high carbon footprints like aluminum, plastics, and foam insulation, thoughtful use is essential. For instance, while aluminum may complement the aesthetics of your project, it is still important to use it judiciously because of its significant carbon footprint.

Choose lower carbon alternatives. Think about the possibilities. If you can utilize a wood structure instead of steel and concrete, or wood siding instead of vinyl, you can reduce the embodied carbon in a project. In most cases, it’s probably not possible to avoid carbon intensive products altogether—metals, plastics, aluminum—but you can review Environmental Product Declarations and look for lower carbon alternatives.

Choose carbon sequestering materials. Using agricultural products that sequester carbon can make a big impact on the embodied carbon in a project. Wood may first come to mind, but you can also consider options like straw or hemp insulation, which—unlike wood—are annually renewable.

Reuse materials. Whenever possible, look to salvage materials like brick, metals, broken concrete, or wood. Salvaged materials typically have a much lower embodied carbon footprint than newly manufactured materials, since the carbon to manufacture them has already been spent. With reclaimed wood in particular, you not only save the energy that would have been spent in cutting the tree down, transporting it to the mill, and processing it, but the tree you never cut down is still doing the work of sequestering carbon.

Use high-recycled content materials. This is especially important with metals. Virgin steel, for example, can have an embodied carbon footprint that is five times greater than high-recycled content steel.

Maximize structural efficiency. Because most of the embodied carbon is in the structure, look for ways to achieve maximum structural efficiency. Using optimum value engineering wood framing methods, efficient structural sections, and slabs are all effective methods to maximize efficiency and minimize material use.

Use fewer finish materials. One way to do this is to use structural materials as finish. Using polished concrete slabs as finished flooring saves the embodied carbon from carpet or vinyl flooring. Unfinished ceilings are another potential source of embodied carbon savings.

Minimize waste. Particularly in wood-framed residential projects, designing in modules can minimize waste. Think in common sizes for common materials like 4x8 plywood, 12-foot gypsum boards, 2-foot increments for wood framing, and pre-cut structural members.

Larry Strain, FAIA, is a principal at Siegel & Strain Architects.

Monday, March 27, 2017

Architects take a stand on the Border Wall


Border Wall Divides Professionals

When President Trump announced his plans to build a border wall, “it felt a little like divine intervention for me,” says Brian Johnson, the principal of Collaborative Design Architects, a small firm in Billings, Montana. Johnson had already been sketching ideas for a border wall that resembled a series of hydroelectric dams, with curved concrete surfaces to foil climbers and a roadway on top for border-patrol vehicles. After Trump’s announcement, Johnson began refining the idea in anticipation of an RFP. He says, “I knew I had developed something capable of being more than just a wall.”

But where Johnson saw opportunity, many other architects felt outrage. “A border wall is just the wrong thing to do,” says Larry Strain of Siegel & Strain Architects in Emeryville, California. “It doesn’t make us safer, it doesn’t protect our jobs, and it is divisive rather than inclusive.” In early March, he and the members of his firm signed a pledge not to participate in the project, although, he says, they’d be happy to design a seat or a gate with the word bienvenidos.

The pledge was written by an advocacy group called the Architecture Lobby, which asked architects to walk off the job on Friday, March 10, to protest the RFP. Among the firms that complied was makeArchitecture of Chicago. According to its director, William Huchting, the six members of the firm stepped outside to discuss their problems with the wall, including its cost and the possible effect on immigrant communities, such as Chicago’s Little Village. “Hardworking immigrants have transformed 26th Street into the most vibrant shopping district outside of Michigan Avenue,” said Huchting. “We fear that this and other thriving neighborhoods will suffer if the wall is built.”

(Read the article here)

Friday, March 10, 2017


#NotOurWall–Siegel & Strain Architects participated in a Day of Action called for by The Architecture Lobby to protest the Trump Administration's call to construct a border wall. This grassroots action coincided with the closure of the first round of Requests for Proposals (RFPs) for the Department of Homeland Security's Southern Border Wall.

For more information about The Architecture Lobby, click here.

Read more about The Architecture Lobby in Metropolis Magazine.

Friday, March 3, 2017

Embodied Carbon Benchmark Study

What is the typical magnitude and range of embodied carbon of buildings?

The Embodied Carbon Benchmark Study is the first stage of the LCA for Low Carbon Construction project funded by The Charles Pankow Foundation, Skanska USA and Oregon Department of Environmental Quality. Life Cycle Assessment (LCA) is the method used to quantify the carbon emissions that occur when extracting materials and making building products, otherwise known as “embodied carbon.” Although there is growing recognition of the need to track and reduce embodied carbon emissions, building industry professionals need better data and guidance on how implement low carbon methods in practice. 

This project compiled the largest known database of building embodied carbon and created an interactive database. This stage of the project established consensus on the order of magnitude of typical building embodied carbon, identified sources of uncertainty and outlined strategies to overcome this uncertainty. The report summarizes the key findings of this research and provides the foundation for stage two of this project, the development of an LCA Practice Guide due by the end of 2017.

You can download the Final Report and Database as well as interact with the data visualization.

Research Team
K. Simonen (PI), B. Rodriguez, S. Barrera, M. Huang, E. McDade & L. Strain

This research was funded by the Charles Pankow Foundation, Skanska USA and the Oregon Department of Environmental Quality. The success of this project would not have been possible without the donation of the original LCA database from Arup as well as additional databases provided by: The International Living Future Institute, Kieran Timberlake, the MIT Concrete Sustainability Hub, MIT DeQo/Thornton Tomasetti, Skidmore, Owings & Merrill (SOM) and the WRAP database in addition to individual LCA studies provided by firms and organizations.