One of the world’s oldest insulation materials has breathed new life into a leaky cottage in Ontario’s Lake of Bays. Architecture firm Stone’s Throw Design and construction company Fourth Pig teamed up to wrap a poorly insulated 1960s home with straw bale for an energy retrofit so effective it reduced energy consumption by 80 percent. Renovated very close to the Passive House standard with a heating demand of just 20 kilowatt per square meter per year, the Muskoka Cottage is a comfortable year-round family haven renovated with an impressive selection of environmentally friendly and energy-efficient materials and systems.



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The designers began the retrofit process by modeling the home in the Passive House software, PHPP, to map out ways to maximize energy savings. In addition to energy efficiency, the designers relied mainly on eco-friendly natural materials wherever possible as well as no added urea-formaldehyde sheets and zero-VOC adhesives, finishes, and sealants to create a healthy home environment.

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Materials from deconstruction were reused wherever possible, from the chimney bricks recycled as flooring in the mechanical room floor to plywood for form work. FSC-certified timber was sourced as was steel roofing and sheet metal for durability and recyclability. Internal retaining walls were made from rammed earth and all interior walls were finished with clay-based earth plaster to improve sound quality, durability, and resistance to mold. Lime crete made from crushed granite and lime was used for the basement slab floors treated with hemp oil, citrus solvent, and carnauba wax floor finish. The exterior walls were also finished with a clay-based plaster with lime stabilization. Denim batt, cellulose, and perlite were used for insulation.

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Related: $20K studio in Virginia demonstrates straw bale can be viable in humid environments

The low-energy home is heated by a wood-fired boiler, while a solar hot water heater powers hot water and supplements radiant heating. An energy recovery ventilator pumps in a steady supply of fresh air treated with a HEPA air filtration system. Energy-efficient lighting and electrical systems, such as LEDs and BX wiring, also help reduce the home’s energy footprint.

+ Fourth Pig

+ Stone’s Throw Design

Images via Fourth Pig

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