Reduce Embodied Carbon With Simple Forms
In addition to adding cost to a project, a complicated design is responsible for increased embodied carbon emissions.
The embodied carbon associated with a building has to do with the greenhouse gases emitted during the manufacturing of products and materials used to construct it. These emissions differ from those that are generated during the building’s operations (i.e., operational emissions). As our buildings have become more energy efficient, the portion of emissions attributable to embodied carbon has become a more glaring piece of the greenhouse-gas emissions pie. Embodied carbon happens before a building is even constructed, so I and many others refer to it as “upfront carbon emissions.”
There are myriad ways to reduce upfront carbon emissions. Integral to building-related efforts is something I term “materiality,” which is a penalty that includes upfront carbon emissions. This is why there is a growing consensus that an important way to reduce emissions is to use less stuff.
As an environmental journalist, I tackle this notion of economizing around materials and products by addressing questions like these: How much do we really need? How are our buildings constructed and deconstructed? How do we achieve more with less? Here I will address the notion of keeping things simple to help minimize a project’s emissions profile from the start.
Simplify, simplify, simplify
The great industrial designer Dieter Rams understood the need for simplicity when he was designing stereos for Braun in the 1960s. He wrote in the late 1970s, “Good design is as little design as possible. Less, but better—because it concentrates on the essential aspects, and the products are not burdened with nonessentials. Back to purity, back to simplicity.”
Design innovator Steve Jobs adopted Rams’s philosophy, observing, “That’s been one of my mantras—focus and simplicity. [But] simple can be harder than complex.”
Seattle architect Mike Eliason, who learned about this approach to design while he was working in Germany, used the term “dumb box” to describe simple buildings. Although Eliason writes about monetary costs, every word applies to upfront carbon costs as well: “‘Dumb boxes’ are the least expensive, the least carbon-intensive, the most resilient, and have some of the lowest operational costs compared to a more varied and intensive massing … Every time a building has to turn a corner, costs are added. New details are required, more flashing, more materials, more complicated roofing. Each move has a corresponding cost associated with it.” Those corresponding costs include carbon emissions.
Contemporary application of an old building type
A square building form maximizes floor area while minimizing perimeter-wall surface area and materials, which in turn reduces upfront carbon. Adding gables and dormers and bump-outs and bays increases surface area and the potential for thermal bridges, as well as the number of materials needed and therefore upfront carbon emissions.
Tedd Benson of Bensonwood and Unity Homes once shared an anecdote about how complexity adds cost and complication: “Years ago, I met a contractor in Montana who simplified his estimating by charging a set amount for each inside or outside corner. Not surprisingly, most of his clients chose simple boxes, and the designers found ways to [introduce] little surprises in the vernacular of the familiar.”
Simplicity was a driving design principle behind the GO Home, which Matt O’Malia and Riley Pratt of OPAL Architecture introduced 15 years ago. It became an instant Passivhaus poster child. The architects have noted that the GO Home “was conceived as a development model for zero-energy, single-family housing that can be delivered at a cost comparable to that of standard residential construction.”
This 1500-sq.-ft. house has a square plan with a minimal form factor (surface-to-volume ratio), a simple gable roof, and four-square windows. It looks like how a child would draw a house, which is probably one of its great attractions.
Much of OPAL’s work is designed this way. When I asked O’Malia about OPAL’s approach to building simply, he noted it isn’t about style: “It’s not just an aesthetic; it’s a way of thinking of building performance and its relationship to the environment. It’s a way of thinking of buildings as systems.”
None of this is new to American home design. The GO Home borrows from a spartan vernacular associated with rural New England, with its timber-frame structure and a compact form that minimizes exterior surface area and heat loss.
Old homes in the Northeast were simple and spare for functional practicality and economic frugality. Roofs were steep to shed snow and water quickly; windows were smaller because glass was expensive and smaller windows meant less heat loss. Simplicity isn’t so much about aesthetics as it is about physics. And building science–informed design plans have proven that simple and small are keys to good home performance.
My takeaways
The conclusion? Stick to simple forms to minimize surface area. Complicated assemblies call for more products and therefore incur higher upfront carbon emissions. Some insulation types, like cork or wood fiber, have lower upfront carbon but are expensive, so minimizing surface area is a good first step in reducing both carbon and cost.
Eliminate jogs, bays, and other architectural complexities that use more material. Not only do they increase upfront carbon emissions and create thermal bridges, but they can also lead to increases in operating costs and related emissions. Be like those New England home builders of yore, and don’t add anything that’s not intended to serve a purpose.
Keep roofs simple. Dormers and valleys increase materials, surface area, detailing requirements, and the potential for leaks. Conversely, simple gables make for “forever roofs” that rarely leak. Orient them in the right direction, and installing solar becomes simpler too.
One hundred and fifty years before the GO Home was built, Henry David Thoreau wrote, “Our life is frittered away by detail … simplify, simplify.” In a world where we need to use less of everything, simplicity should drive every design.
—Lloyd Alter is a former architect and developer. His journalism career includes 15 years as a contributor at Treehugger.com. Today he teaches sustainable design at Toronto Metropolitan University. His work can be found at Carbon Upfront.
From Fine Homebuilding #316
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