Design Architecture From the Straw Bale Wrap to the Lime Plaster Finishes, This Cottage Is as Green as It Gets By Lloyd Alter Design Editor University of Toronto Lloyd Alter is Design Editor for Treehugger and teaches Sustainable Design at Ryerson University in Toronto. our editorial process Facebook Facebook Twitter Twitter Lloyd Alter Updated October 11, 2018 Share Twitter Pinterest Email Design Tiny Homes Architecture Interior Design Green Design Urban Design Lake of Bays is a dumb but appropriate name; it is a big lake with lots of bays in Muskoka, a summer playground that attracts the wealthy from Southern Ontario and the Northeast United States. The big three lakes in Muskoka attract the movie stars, big boats and monster cottages; Lake of Bays attracts quiet money and they don’t flaunt it to quite the same degree. It is surrounded by much smaller, more affordable lakes. It’s also apparently a hotbed of sustainable design, with a summer office for architect Terrell Wong of Stone’s Throw Design, and the Fourth Pig Worker Co-op, a construction company with a mission “to foster ecologically balanced methods of construction and energy production in order to promote more sustainable and healthy communities.” On a personal note, I am writing this from my cabin in Lake of Bays, just a few miles from both of them. © Stone's Throw DesignTerrell Wong’s motto is “Conservation over technology; longevity over fashion” and it shows in her latest project on lake of bays. It is an almost passive renovation of an existing house from the 60s, that has been wrapped in straw bale for insulation. © Stone's Throw Design It’s heated by a wood fired boiler, which also heats the domestic hot water and water for radiant heating (via baseboard heaters). The house is pretty much foam free, with perlite insulation under the basement slab. Conventional foam insulations are considered a problem because they are made from fossil fuels, filled with dangerous flame retardants and because of the global warming potential of the propellants. But it’s hard to find alternatives for foam in basements; Perlite is an interesting choice: When perlite ore is expanded by exposure to rapid, controlled heating, it grows up to 20 times its original volume and takes on a foam-like cellular internal structure—essentially clusters of microscopic glass bubbles. This physical transformation makes expanded perlite an extremely efficient, low density insulator. The basement slab itself is Limecrete, another unusual choice. It is “ a combination of natural hydraulic lime and lightweight aggregate which can be used as an alternative to concrete.” -eliminating the need for portland cement. It was then “treated with hemp oil, citrus solvent, and carnauba wax floor finish.” © Stone's Throw Design/ Riley Scott Interior walls are all finished in natural materials, either wood, lath and plaster, and clay based plaster “ to improve sound quality, improve durability and avoid toxins, mold vulnerability and embodied energy of drywall.” Even the wiring itself is the greener choice: expensive metal-clad BX wiring to minimize electric magnetic fields (EMF) and avoid PVC insulation. © Stone's Throw Design This is really a remarkable achievement; an incredibly energy efficient renovation using the healthiest of materials with the lowest carbon footprints. Behind that modest and subdued exterior, it is just full of green secrets. Nice work by Fourth Pig and Stone’s Throw Design. UPDATE: There are a lot of concerns expressed in comments about the use of the wood stove. Note that the house is "almost passive" using only 20kWh/m2 per year so there is not a lot of wood being burned. Our position has always been that reducing demand is the best way to deal with the problem of energy consumption. We also recognize the issues and problems about burning wood and have addressed some of them on TreeHugger, and will look at this issue in greater detail shortly. UPDATE 2: Please read Can a house where wood is burned for heat really be called green?