Episode 4: Surprise CO2 Savings
The construction industry uses three quarters of all the raw materials used by the United States, while buildings consume nearly 40% of energy in the country, more than both transportation and industrial sectors. Almost half of the greenhouse gas emissions stemming from buildings are due to materials production and the burning of fossil fuels. The process of construction creates a lot of waste, contributing between 30% and 40% of domestic landfill waste.
Steve Pallrand founded CarbonShack Design in 2016, an offshoot of Home Front Build, his original firm that remodels historic homes in Los Angeles. CarbonShack combines design and technology to build low-impact homes and empower homeowners, through visual cues and sleek design, to be stewards of their environment.
There are two categories used to measure the carbon footprint of a home: embodied systems and operational systems. The embodied systems include everything that goes into constructing the building (production and transportation of materials). The operational systems consist of the energy required to run the house after it’s constructed, and what savings there are (i.e., on electricity, heating/cooling, and water systems). Since the operational systems are hidden from view, CarbonShack is interested in designing the finishes to underscore visually—through furniture, fabric, lighting, and tiles—as a visual connector to the environmental goals of the home.
As technology marches forward and buildings become increasingly energy-efficient and renewable-based—decreasing their operational carbon footprint—the production of materials used in construction begins to take up a larger proportion of the embodied carbon footprint. The “greenest” option is usually to work with what you’ve got, repairing and updating your home rather than doing a whole remodel, but if you’re starting fresh, using reclaimed and salvaged materials is the most environmentally friendly option. CarbonShack works to maximize reclaimed, recycled, and low impact materials in their projects.
An inventory of salvaged materials served as a launching point for CarbonShack’s first major project, a case study house which would build out their company. Casa Zero was built using hardly any newly constructed materials. During this project, the firm also ambitiously set out to achieve LEED Platinum certification, becoming one of the few homes in LA with this certification.
Architecturally, CarbonShack designed the layout to enable passive heating and cooling. Casa Zero sits on the edge of a hillside with a valley below. Bifold doors face the hillside, opposite clerestory windows. When opened, airflow heats or cools the house depending on the season. It cools Casa Zero by releasing hotter air in the higher portions of the house and bringing cooler air into the lower part. Motorized window coverings connect to thermal sensors so that when direct sunlight hits the windows, the shades go down to insulate against heat. The house hosts a heat pump system instead of hot water heaters, and the AC unit works like a fridge, so that the heat released through energy production is used to heat and cool the house more efficiently.
Casa Zero was built using 95% old lumber, cutting carbon from 3.7 to 0.9 tons. According to the Environmental Protection Agency, 48% of lumber that is sent to the landfill every year can be reused. CarbonShack calculated that using just half of that 48% would save 1.5 million acres of forest, 9.5 million tons of wood, and 1.5 million tons of CO2 each year, equivalent to taking 300,000 cars off the road. Using the embodied energy calculators developed by the CarbonShack team, they were able to determine that in total, Casa Zero saved 15 tons of CO2 from being released into the atmosphere.
CarbonShack sourced materials with low carbon costs to design the house. The fabrics were all recycled or upcycled, and any new fabrics were made from hemp, a UV and mildew resistant fabric. One pound of hemp textile takes 40 gallons of water to produce, while a pound of cotton textile uses up 2,500 gallons. So not only is it a more durable material, it also is less water-intensive. Using hemp fabrics reduced the fabric-related CO2 footprint of this project by 85%.
New stone and brick have high carbon costs. Bricks require the mining of clay and firing processes, and since they are usually produced outside of the US, in places with fewer regulations, they are often fired using coal or open fire burning. Stone must be quarried—using dynamite, blasting, and cutting—and comes from far away, like Brazil and China, meaning they carry with them the carbon costs of their transportation. Terracotta tiles provided a surface with longevity (versus something like vinyl or wood). They were sourced from clay mined in Sacramento, and formed, hand-glazed, and fired in Los Angeles using electric-powered kilns.
The lighting in Casa Zero is all LED, with large fixtures produced locally. The furniture in is almost all vintage or rehabilitated heirloom pieces, with new pieces built from wood CarbonShack had from previous projects.
CarbonShack used the processes and knowledge learned from the Casa Zero case study, applying them to the seven projects they have completed subsequently. Let’s take a look at how the firm has made environmentally-friendly swaps in some more areas of the design-build process.
Lumber
CarbonShack has been able to find many resources for reusing lumber. They bought a redwood bridge built a century ago in California that was going to be torn down, avoiding the bridge going into the landfill and the carbon footprint of buying new lumber. They also purchased mahogany pews from a church in LA that were going to be thrown out. They are able to mill and use this lumber to make furniture and paneling for homes. CarbonShack works with companies that find out about trees that need to be taken down (i.e., due to streets being widened by the city), and then salvage and mill them into lumber. This gives new life to high quality, old lumber, and serves as a store for carbon sequestration. Today, almost all lumber companies monocrop the forest, growing one kind of tree, which they then must spray with chemicals, resulting in poorer quality wood that is susceptible to infestation, and a weaker overall forest. On top of this, the US Forest Service projects that within the next decade or so, US forest will begin to shrink by 250,000 acres a year, and so CarbonShack’s commitment to repurposing old lumber will become increasingly important.
Concrete
It is hard to avoid using concrete in construction, but one way that CarbonShack minimizes its carbon impact is to incorporate fly ash, a byproduct of coal burning, into its cement mixture. This not only reduces the amount of concrete needed in the cement (concrete inherently releases CO2 as a byproduct), but also removes the toxic fly ash from the atmosphere through sequestration in cement. CarbonShack usually uses 15% fly ash concrete—manufacturing costs associated with making a higher-percentage batch are high—but strives for higher percentages, ideally between 20%-30%.
Landscaping
CarbonShack uses Xeriscape landscaping, meaning it uses only low-water, drought-tolerant species. For example, the Casa Zero property is filled with principally native species. Since it is on a hillside, the firm built terraces to help retain moisture, and any irrigation is sourced from rainwater and greywater from the house. The emphasis CarbonShack wanted to make was not a lush, green landscape, but rather one that is influenced by the climate and season: a living, breathing indicator of connection to the natural world.
Kitchen & Appliances
Creating all-electric homes that do not depend on fossil fuels is a key goal for CarbonShack. They recommend electric induction cooktops that work by magnetic connection. Advancements in this technology have made induction stoves heat-sensitive and very adjustable, combatting the romanticization of gas stoves by the gas industry. They are also much more efficient than gas stoves at heating food quickly and evenly, and don’t let off all of the greenhouse gasses that gas stoves do. CarbonShack installs touchless water faucets in bathroom sinks, which leads to enormous water savings when performing kitchen tasks. Most appliances now offer versions with high energy star ratings, and so CarbonShack will look for these when outfitting homes. Everything that goes into a home is reconsidered by their team to determine how it could be changed or improved to reduce the carbon footprint of a project.
Filling Market & Informational and Resource Gaps Sustainably
In addition to helping clients lower their carbon footprint, CarbonShack has its own initiatives to help fill gaps in the market and provide information accessibly. They opened a showroom to sell products designed to be healthy in the home, like furniture made with non-VOC finishes and entirely biodegradable fabrics. This line is all made locally using energy- and waste-efficient manufacturing processes, and includes lighting, textiles, cabinetry, tiles, and furniture. To supplement their projects, CarbonShack has built out a digital library with open-source educational and informational materials, as well as a user-accessible, free online carbon calculator for homeowners anywhere. Not only can users calculate their home’s carbon footprint, but they can also receive guidance as to navigating toward lower carbon appliances and technologies in their home.
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As we move into a future with a changing climate, we must consider how the structures we live in both shape and are shaped by the environment surrounding us. Building energy-efficient homes could have significant impacts on greenhouse gas emissions reductions, and could also serve as protection in the face of energy crises and/or shortages. Los Angeles needs more firms like CarbonShack, and a large-scale transition away from McMansions and luxury developers in order to begin to address both climate and environmental justice needs.
