How to build your own passive house or remodel
Barbara and Greg Whitchurch
In this article, we’ll describe how you might go about building your own Passive House (PH) or remodel.
First: Get a certified PH professional. Try Vermont Passive House (bit.do/vtph-mem) or Efficiency Vermont (bit.do/een-evt) to find people who are certified to build to the PH standard. There are many of these builders and architects in New England. (More: bit.do/phius-cphc and bit.do/phi-cphc.)
Your project’s lead consultant will run the WUFI Passive or the PHPP program. (Matt Lutz says that every high-performance home project should have such a person on board.) If you want an architect, but your builder is the lead consultant, then the architect doesn’t need the designation.
[The Dawkins (see Part 1 on page 28 of this issue) had Chris Miksic and we had Indigo Ruth-Davis (both of MontpelierConstruction.com/) as our lead PH consultants. We built our PH in 2014 without an architect or designer. Greg drew diagrams of what we wanted. It was the first PH effort for any of those involved. But, since the PH process guides builders in such detail, we were nonetheless assured a great performing building. It was the team’s very first – award-winning! – PH effort here: bit.do/phc-vtbiz]
Second: Line up your incentives. These are your own tax and utility dollars being targeted right back at you to encourage more responsible choices for everyone’s sakes. These incentives add up to many thousands of dollars, and considering that your electric car can serve as grid backup for your house, they cover electric vehicles (EVs), cooking, heating and cooling, hot water, fridges, weatherization upgrades, bikes, lawn mowers, etc. Your certified PH consultant (CPHC) should be aware of all these opportunities. (E.g., bit.do/evt-hphp, in MA there’s a special incentive for PHs phmass.org/masssave/.)
Third: Your mortgage. Be sure your bank employs a Certified Green Appraiser who uses the green addendum (http://bit.do/ai-green-appraisal). More info: bit.do/vbra-appraisal. In VT: bit.do/evt-loans, bit.do/vsecu-vgreen.
PH is too expensive: Two of Vermont’s PHs are Habitat for Humanity homes. We know of folks who are not well-to-do who have PHs (including us). If your builder claims PH is not worth the effort, ask them about the certified PH they built that disappointed them or their clients.
Net Zero is good enough. The Dawkins (soon), our, and many other PHs are net zero – no big deal. With enough money and solar panels you can net zero a stone castle. PH requires very few solar panels to net zero, saving money, space, and resources. Also, net zero does not address comfort, health, or maintenance, while PH does.
A house needs to breathe. If you hear this from a builder, they’re actually saying that their construction method depends on air leaks to keep the walls from rotting. A house needs to be sealed and vented in specific ways. Airtightness is of paramount concern in any modern building. Blower door testing should be run on any new house multiple times during construction. PH guarantees all of this.
Some old-fashioned ideas and baggage to be rethought for any modern home: basements, steeply-pitched roofs, wood stoves, attics, and more.
E.g., basements no longer need to serve as foundations, root vegetable storage, or housing for your messy furnace or boiler, hot water heater, water pump, pressure tank, and fuel storage. All of these functions are minimal in a PH and can be housed in a large closet anywhere. The Dawkins’ house has a pull-down ceiling ladder to a tiny mechanicals room in the attic space. A simple concrete slab or pier system often serves as the foundation of modern homes. And heated floors are absolutely unnecessary.
A flat-ish roof will save lots of lumber and keep the snow off your shrubs, sidewalks and entryways, while using that snow as a very effective insulating blanket.
Do you still think of windows as views and light sources only? PH nudges you to consider their energy costs and benefits, too. Proper solar consideration can make huge differences in your energy use and comfort throughout the year.
Remember: You can always finish or upgrade countertops, lighting, cabinets, bath fixtures and floors later on with your energy savings to avoid overburdening your original mortgage. But you only get this one chance to correctly design the continuous insulation, air sealing and non-thermal-bridging of the walls, roof and foundation assemblies.
Conclusion: Keep in mind that PH is not the end of a continuum – one can get much more careful about sustainability, environmental impacts, and energy use. PH is designed to hit the sweet spot where a smaller investment costs you a lot more in the long run, while more investment gets you relatively little extra performance. By staying focused on the outcomes of your choices, PH allows you to make informed choices based on proven engineering science.
All of the considerations and metrics involved in PH also exist in every other type of home — the performance characteristics of the lumber, insulation, windows, and appliances for ANY building are available from the manufacturers. But PH actually uses this information effectively, instead of relying on advertising, store sales, contractor markups, and the builder’s feelings about how things should be done.