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Round House Curve Appeal
In the small town of Nebaj, about six hours north of Guatemala City in Guatemala, Elba Méndez and her family have preserved the country’s vernacular architecture form by building a round home from a mixture of cob and cordwood. “We wanted to build an earthen home because they’re so much nicer than the block and cement homes everyone is building around town,” she says. “We also wanted to make a round home because no one else in town has a circular house.”
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Circular homes don't have corners that end up gathering dust. Generally speaking, round homes allow for more efficient use of space, and creative interior design with natural flow between spaces. As an added benefit, round homes are generally less expensive to build. The lack of complicated structures and multiple surfaces can require up to 20 percent fewer materials per square foot of construction, thus driving down the final cost.
3. Energy Efficiency of a Round House
Round homes are more energy efficient than their rectangular counterparts. Why? Because they have less surface area relative to floor space, there is less wall exposure to the exterior elements. This allows homeowners to invest in high-efficiency insulation and high performance windows in strategic wall spaces to maximize the energy efficiency and thermal performance of the home.
According to Leigha Dickens, Deltec’s Green Building and Sustainability Manager, “The radial design of our trusses, meaning they radiate from a center point like spokes on a bicycle wheel, adds considerable strength to the structure, while the round shape helps reduce wind pressure. Both of those features contribute to an incredibly strong structure, and we specialize in high wind design.” With global climate change increasing the likelihood of strong hurricanes and other extreme weather events, stronger structures are essential for a resilient home.
The Innovation Center’s round model home incorporates other sustainability elements, including passive solar design, super-insulation with R-values and window performance values well above the local energy code, air-tight construction, and fresh air ventilation. The home has high-efficiency heating and cooling, hot water, lights, and appliances. The all-electric home is paired with a grid-tied solar array sized to offset the home’s yearly energy use through a net-metered system.
The model’s structural shell is constructed indoors in a facility that uses renewable energy. Together with a 5.12 kW grid-tied solar array, all of these sustainability features allow the center to achieve Net Zero energy status.
Central America: Cob/Cordwood Round House
The town of Nebaj averages close to 60 inches of rain each year and many of the town’s new cement homes have severe problems with humidity and mold. “Earth homes are cooler during the day and warmer at night and don’t have problems with excess humidity,” says Méndez. “We also knew that adobe homes are not exactly earthquake resistant, so we learned about cob construction at a natural building workshop and decided to go that route.”
Cob construction, an ancient building technique, is similar to the traditional adobe construction in that it uses a combination of moderate clay soils and straw. Unlike adobe, however, cob is considerably stronger. Cob’s clay and sand combination give the walls good compression strength, whereas the use of straw or other fiber-like material offers optimum tensile strength.
Tobias Roberts
Tobias runs an agroecology farm and a natural building collective in the mountains of El Salvador. He specializes in earthen construction methods and uses permaculture design methods to integrate structures into the sustainability of the landscape.
