Graham Whiting of Whiting Design has been working on a Passive House design for a family of permaculture farmers south of Guelph, Ontario. TreeHugger Sami has written a lot about Permaculture, and says "the idea behind permaculture gardening is to use nature's own design tricks to create productive landscapes that do much of the work for you." That is pretty much what Passive House designers try to do- let the fabric of the building do the work of keeping you warm or cool instead of a lot of mechanical equipment and fossil fuels.
In his book Permaculture: Principles and Pathways Beyond Sustainability, David Holmgren listed twelve design principles, the most relevant of which I include here.Produce no waste: By valuing and making use of all the resources that are available to us, nothing goes to waste.
Whiting has designed a house at Wild Leek Farm that is almost more permaculture than Passive House. It is a simple form, a classic farmhouse of the kind that North Americans have been building for hundreds of years. Keeping it simple made it more affordable and enabled the owners to do a lot of the work themselves. Keeping it as a straightforward classic form made it easier to frame: "Careful attention was paid to advanced framing details, minimizing stud use and thermal bridging wherever possible." Nothing is wasted on jogs and bumps- it is economical and simple.
Use and value renewable resources and services: Make the best use of nature's abundance to reduce our consumptive behavior and dependence on non-renewable resources.
It is not extravagant with resources. Take the windows; they are not huge floor to ceiling things, but designed with moderation. Engineer Nick Grant has noted that windows are much more expensive than walls and are lovely things, but truly a case of where you can have too much of a good thing, causing "overheating in summer, heat loss in winter, reduced privacy, less space for storage and furniture and more glass to clean."
Graham has thought about this and considered "Careful placement and optimization of triple glazing percentage based on solar orientation and window to wall ratio." There's more, something I had not thought of before: "Windows and doors are sized and aligned to fall on natural stud locations to avoid double and triple studs unnecessarily."
Use small and slow solutions: Small and slow systems are easier to maintain than big ones, making better use of local resources and producing more sustainable outcomes.
Passive House design has always been a sort of slow design solution. TreeHugger Collin once defined Slow Design:
Just like Slow Food, it's all about using local ingredients, harvested and put together in a socially and environmentally responsible way. Above all, it emphasizes thoughtful, methodical, slow creation and consumption of products as a way to combat the sometimes overwhelming pace of life in the bigger-faster-now 21st century.
So the house is insulated with dense pack cellulose, the insulation with the lowest embodied energy. It is also healthy and local: "All materials used in the construction are selected for low toxicity, natural sourcing, and local economic benefit." It is carefully sited to "maximize access and interaction with farming operations, overlap of function (space for food processing, drying, and storage), and careful integration of site servicing, septic, driveway etc. to maximize solar and arable land while preserving windrows and woodlot." That all sounds slow and thoughtful to me.
Catch and store energy: By developing systems that collect resources at peak abundance, we can use them in times of need.
Passive House designs do that, and the roof covered in solar panels collects a lot of resources.
Graham has designed a house with a building fabric that limits air changes too .034 ACH, a seventh as much as the relatively tough Ontario building code allows. They house uses 87 percent less energy than a house of the same size built to code. Data nerds will appreciate other numbers:
- Wall R-value = 51.6
- Roof R-value = 84
- Annual Space Heat Demand = 5.52 kBTU/sq.ft (17.4 kWh/sq.m)
- Annual Overall Primary Energy Demand, including space heating and PV = 14.77 kBTU/sq.ft (46.7 kWh/sq.m)
Graham tells us that the house is doing better than expected:
Modeled energy consumption averaged 2400kWh per month, whereas actual has been only in the 800-1200 range. PV production has been greater than consumption for 5 months running now, for a substantial surplus. But we need to make it through a winter before celebrating too much!
Observe and interact: By taking time to engage with nature we can design solutions that suit our particular situation.
In a lot of ways, Passivhaus and permaculture are a perfect mix; So many of the permaculture design principles are applicable to architectural design. Graham Whiting has certainly observed and interacted, and he really has designed a solution that suits the particular situation. There are a lot of lessons here.
UPDATE: Architect Bronwyn Barry has noted that "Passivhaus is a team sport" and Graham Whiting reminds me, noting that the Evolve Builders Group and others had a big hand in this. "...a lot of the advanced framing, air tightness details, etc. were 100% their initiative as part of a fully integrated design team." Also involved:
Rob Blakeney - mechanical
RDH Building Consulting - building envelope consultants
Blue Green Group - Passive House Rater / Certifier