On my second day in Maine, I toured seven energy-efficient buildings in various stages of construction. In last week’s blog, I reported on my visit to Richard Renner’s office and Jesse Thompson’s house. This blog picks up the story with a report on my visit to three sites: an ongoing deep-energy retrofit project, a new home in Falmouth, and an unusual co-housing project.
If you’re the type of reader who prefers pictures to words, you’re in luck: this week’s blog is loaded with photos.
Curious regional differences
After I returned home from my Maine visit, I pondered the similarities and differences between building practices in New England and building practices in the Pacific Northwest, where I visited several job sites in March 2011.
On both coasts, energy-efficient builders have embraced triple-glazed windows. But insulation practices are starkly different: in Washington state, all of the energy-conscious builders are using blown-in fiberglass insulation, while Maine builders are all choosing cellulose. I have no explanation whatsoever for this startling difference in insulation practices.
A post-and-beam house gets a deep-energy retrofit
Claudia King and Lindsey Tweed own an old post-and-beam house on a picturesque rural site in Falmouth, Maine. With diverse views in all directions — a large pasture, patches of woods, and a nearby pond — it’s easy to understand why someone would fall in love with the site and the existing house.
A team of professionals — including architect Phil Kaplan, energy consultant Marc Rosenbaum, and builder Dan Kolbert — have been collaborating on a deep-energy retrofit of the home. When I visited the site on the morning of June 8, 2011, workers were moving soil in preparation for a new driveway, building a stone retaining wall, and installing siding and exterior trim.
To improve the home’s energy performance, the siding and windows were removed and the walls were gutted. Because the original studs were scabbed together in a haphazard way, and because it was necessary to reframe the window openings, the old studs were removed and new 2×6 studs were installed between the posts of the existing timber frame. The stud bays were later filled with dense-packed cellulose insulation.
The walls were sheathed with new Zip System OSB panels. This sheathing was then covered by a layer of 2-inch-thick polyisocyanurate, followed by a layer of nailbase consisting of 2 inches of polyiso with a facing of OSB. (This second layer of OSB facilitated the installation of the siding.) After the nailbase was up, the crew installed Tyvek, (to create a drainage layer), and new cedar shingles. The completed wall assembly is rated at R-44.
The basement walls are insulated on the exterior with two layers of Roxul mineral wool with a total thickness of about 4 3/4 in.
The house has new with Heat Mirror glazing (two layers of glass and two suspended plastic films). The windows are installed as “in-betweenies” (rather than innies or outies), with a nice trim detail on the exterior: the exterior jamb extensions are finished with cedar shingles with woven corners.
Space heat will be provided by a combination of ductless and ducted minisplit air-source heat pumps.
I already mentioned this retrofit job in a previous blog, when I reported on my conversations with Phil Kaplan and Claudia King on their approach to nailing down the insulation specifications for this house. At first, Claudia and Lindsey hoped the house would achieve the Passivhaus standard. However, after Marc Rosenbaum used PHPP software to determine what it would take to get there, they abandoned the idea. (Even R-44 walls weren’t good enough; the PHPP software pointed towards the need for R-56 walls.) They decided that they couldn’t justify spending thousands of extra dollars on Passivhaus levels of insulation to save just a few more BTUs per year. Although their superinsulated home won’t achieve the Passivhaus standard, it will still have a thermal envelope that is far superior to typical residential construction.
Like many other deep-energy retrofit projects, including the retrofit of Jane Bindley’s ranch house in New Hampshire, the extensive work at Claudia and Lindsey’s house will cost more than it would have cost to demolish the existing house and build a brand-new superinsulated home. The high cost of these projects certainly complicates any future policy decisions concerning our national response to the climate-change crisis.
For more details on the project (as well as on the other homes mentioned in this blog), be sure to click on the photos and read the captions.
Small and energy efficient
I next visited a compact, energy-efficient house in Falmouth owned by Stewart MacLehose. The new-construction project was designed by and built by Dan Kolbert.
Among the interesting features of the 3-story, 2,500-square-foot LEED Platinum house:
- Wall construction: 11.25-in.-thick double stud walls filled with dense-packed cellulose.
- Roof assembly: an insulated sloped ceiling with 14-in.-deep unvented rafter bays filled with dense-packed cellulose.
- Windows: Thermotech fiberglass windows with triple glazing.
- Finish flooring: tinted concrete slab on grade.
- Space heat: Solar thermal system (roof-mounted evacuated tube collectors) with electric-resistance backup.
- Heat distribution: In-floor hydronic tubing on first floor only.
- Domestic hot water: Solar-thermal system with electric-resistance on-demand water heater as backup.
- Mechanical ventilation: American Standard ERV.
- Blower-door test results: 0.77 ach50.
Dan Kolbert likes the fact that the house is compact and simple. “Engineering is the enemy,” says Dan.
This attractive house is a true energy miser. To learn more about the home’s construction details, be sure to read the that Dan Kolbert wrote for the Journal of Light Construction.
Top-quality materials will ensure low maintenance costs
The next job site I visited was highly unusual. Two buildings are under construction on the 17-acre site: a very large (11,000-square-foot) building, the size of a small school, and a nearby 3,300-square-foot building the size of a large single-family home. The big building is a co-housing development designed to accommodate three families; it includes a common meeting area. The smaller detached building is a five-bedroom guest house. The project includes a garage with five vehicle bays and an apartment for a future care-giver.
The buildings at the Southern Maine Co-housing Project were designed by Richard Renner Architects, with help from energy consultant Marc Rosenbaum. The project is being built by Wright-Ryan Construction under the direction of project manager Don Hawkes.
I used to work as a roofer, so the first thing I noticed at the site was the lavish use of copper. All of the buildings are roofed with standing-seam 16-ounce copper. Copper also covers the dormer cheeks, fascia, soffits, and window sills. For a copper junkie like me, it’s a stunning project.
Copper was specified for the roofing and flashing because the clients requested exterior details that require minimal maintenance. They also told their architect that low energy consumption is a high priority. The project includes a 25-kW photovoltaic array — large enough to generate as much electricity as the buildings consume.
Some project specifications:
- Basement slab insulation: 4 in. of continuous horizontal XPS under the slab.
- Basement wall insulation: 3 layers of 2-in.-thick polyisocyanurate on the interior of the walls.
- Above-grade wall construction: 2×6 studs filled with dense-packed cellulose, with two layers of 2-in.-thick polyisocyanurate foam on the exterior of the walls sandwiched between two layers of OSB (“site-built SIPs”).
- Windows: Serious Energy 925 windows with Heat Mirror glazing (two layers of glass and two suspended plastic films), installed as “innies.”
- Space heating: a central wood-pellet boiler (an from Austria); pellets will be delivered by truck and blown into a basement bin.
- Domestic hot water: a solar thermal system.
- Mechanical ventilation: Renewaire ERVs.
In next week’s blog, I’ll report on a visit to a new-construction project in Freeport designed by Chris Briley and built by Dan Kolbert, as well as a tiny new energy-efficient home being built by GO Logic in Bath.
Last week’s blog: “Visiting Energy-Smart Designers and Builders in Maine.”