Editor’s Note: The submissions for homes featured in this post came from home owners, builders, architects and renewable energy professionals across the state. We reviewed data for all of the submissions received and selected the five homes that you will see featured in these pages. As you will see, they represent a diversity of size, style, geography, methodologies, price and performance, showcasing a variety of options for Maine homeowners. There are two deep energy retrofits, existing homes that underwent extensive renovation resulting in superior improvements to their energy performance, and three newly constructed properties, where energy and performance was a goal of the design and build from the start. For each project, you’ll find an overview of the home, a summary of what we like about it from a technical perspective, details about the approaches implemented in the house and the performance it has achieved.
Read more about What makes a high performing house.
Rockport, Maine: Accomodates a large family with minimal maintenance
EFFICIENCY: $500 annual energy costs, 89% of the way to Net Zero
SLAB- 4” extruded polystyrene insulation under concrete, R-20.
FOUNDATION- Insulated Concrete Form walls, R-22.
WALLS- Double Stud walls with 11” of Dense Packed Cellulose insulation, R-43.
ROOF- 2×12 rafters with dense packed cellulose insulation plus 2” of foil faced rigid foam insulation on the interior (taped and sealed), R-50.
WINDOWS- triple pane Canadian windows.
AIR TIGHTNESS- did not pursue a test out, but was designed to meet passive house standards.
HEATING AND COOLING- Ductless mini split heat pumps.
VENTILATION- Air Pohoda iERV (acts as both an ERV and HRV providing continuous fresh air and controlling humidity)
RENEWABLES: 9kW solar PV array, two flat panel solar hot water system.
SIZE: 3,400 ft2
COST: $275/ ft2 (excluding land)
DESIGNER: Charles Treat Arnold, Etna, NH
BUILDER: Limoges Builders, Rockport
RENEWABLES: ReVision Energy, Liberty
ENERGY/PERFORMANCE CONSULTANT: Kaplan Thompson Architects
With their five children grown and gone from the home, Tom Kiley and Ry Hills wanted to downsize, simplify and reduce maintenance when they envisioned their new home. They wanted the house to be simple to run, easy to clean, require minimal yard work, and at the same time be an enjoyable and comfortable house. Further, as the Kileys frequently travel, it needed to be a home that they could leave for a short time in any season and not worry about anything.
The house was designed to accommodate regular visits from their children and grandchildren, but allow for them to live on one floor when it’s just the two of them. Words that came to mind as they were describing the project were Shaker simple, Zen, Scandinavian and modern, yet tried and true traditional Cape.
The result is a 3,400 sq. ft, three-story home with just $500 a year in total energy costs. It was designed using LEED and passive house methods, and while they didn’t pursue either certification, they say these guides were paramount in their goal to diminish the environmental impact of house building and ownership over the long term.
Why we like it: This house embraces New England Vernacular design and demonstrates how cutting edge energy efficiency techniques can be incorporated into a traditional aesthetic with mass appeal. The home features a robust exterior building envelope consisting of double stud walls filled with dense- packed cellulose (a foot thick), solar thermal and photovoltaic panels, and high efficiency mechanical systems.
West Kennebunk, Maine:
Net positive home produces more energy than it consumes
EFFICIENCY: More than Net Zero, Net positive. Utility bills of $4.38/month (the cost of staying connected to the grid)
FOUNDATION- A typical 4ft frost wall. The first floor (above the crawl space) was sheathed and filled with dense packed cellulose.
WALLS- Double Stud walls with 12” of Dense Packed Cellulose insulation, R-42.
ROOF- 13” engineered wood rafters with dense packed cellulose, R-52.
WINDOWS- triple pane Canadian windows, Douglas fir casements.
AIR TIGHTNESS- Did not pursue a test-out. Proof is in extremely low utility costs.
HEATING AND COOLING- a single ductless mini split heat pump (wood stove backup).
VENTILATION- 80% efficient ERV (energy recovery ventilator)
RENEWABLES: 6.89 kW solar PV array: Currently producing at least 1000 kWh/yr more than the house consumes.
SIZE: 1,390 ft2
COST: $298,000 ($214/ ft2)
DESIGNER: Noah Wentworth, Evergreen Building Collaborative / Chip Flanagan, Maine SunWorks
BUILDER: Noah Wentworth, Evergreen Building Collaborative / Chip Flanagan, Maine SunWorks
RENEWABLES: Maine Solar Solutions
ENERGY/PERFORMANCE CONSULTANT: N/A
Al and Vicki Adams wanted their retirement home to be a comfortable, low-maintenance house that was also cozy and carefree (there’s a theme here). Working with Noah Wentworth of Evergreen Building Collaborative in Arundel, the end results is truly remarkable – a net positive house (it produces more energy than it uses) at just $214 a square foot. This 1,390 square-foot home cost $298,000 to build (inclusive of all construction, site prep and even the solar panels). The only thing not included in this price was the land. They prioritized local materials—all tiles and wood floors were sourced in Maine. All appliances came from the Habitat for Humanity ReStore, to which Al is quick to point out, “And you cannot even tell.”
Like most super tight houses, the Adams’ home utilizes a heat recovery air exchanger that removes stale indoor air, replacing it with fresh outside air, while retaining 80% of the heat that would otherwise be lost.
The Adams have plans to get an electric car in the near future and have estimated that they are producing enough extra energy each year to support 6,000 miles/year on the electric car.
Why we like it: So many new high-performance houses these days are expressed in a very modern aesthetic. There’s nothing wrong with this. In fact, it can be very refreshing and engaging. However, it often gives the impression that this is a necessary part of being a high performance home. This house like the Rockport house, wonderfully demonstrate how traditional aesthetics can lend themselves to sustainable design. This house has the added benefit that it can be done for a cost comparable to “standard” custom home construction.
19th Century aesthetics with 21st century energy performance
EFFICIENCY: HERS score -2, Net Zero, All electric. Energy bills are only $17/mo. for the house and connections, and $40/mo. for two electric cars.
SLAB- poured concrete floor over 2” XPS rigid foam board, R-10.
FOUNDATION-Poured concrete basement walls insulated with 2” of thermax polyiso insulation board, R-14.
WALLS- Double Stud walls with 9.5” of Dense Packed Cellulose insulation and an additional layer of 2” of rigid foam insulation on the exterior, R-47.
ROOF- Unvented “hot roof” with 2” of rigid foam board insulation under the plywood sheathing (between rafters) and the rest of the rafter cavities filled with dense packed cellulose, R-60+.
WINDOWS- standard double pane windows.
AIR TIGHTNESS- ACH50 – .92
HEATING AND COOLING- Two ductless mini split heat pump, though only one has ever needed to come online.
DOMESTIC HOT WATER- Heat Pump water heater.
VENTILATION- Exhaust only, continuous ventilation. Panasonic Whispergreen exhaust fan. One in each bedroom.
RENEWABLES: 9.6 kW solar PV array
SIZE: 2,300 ft2
COST: $477,100 (includes solar, excludes the Barn, $80,000)
DESIGNER: Bob Howe/Kathy Coleman, and Fred Hahn, Building Designer in Bath drafted the plans
BUILDER: Bob Howe/Kathy Coleman, general contractors
RENEWABLES: ReVision Energy
ENERGY/PERFORMANCE CONSULTANT: Wes Riley
A self-proclaimed “energy-efficiency geek,” Bob Howe heads up the Maine Association of Building Energy Professionals (MABEP). He tells us that he built thermal shutters for his first home during the oil embargo of the 1970s, and has been on the path to high performing homes ever since.
When designing their home, Bob and his wife Kathy Coleman wanted a home that looked like it belonged in the historic neighborhood where they live, but without that low performance that typically accompanies antique houses. In fact, they have achieved quite the opposite. The house is net zero, and is certified by Energy Star as having a HERS rating of -2, which actually makes it slightly net positive. This house produces more energy than it consumes. Super insulated with high tech design and air sealing, the 2,300 square-foot home is heated entirely with a single 12,000 btu Fujitsu mini split heat pump.
One of Bob and Kathy’s goals in designing the house was to show that a high performing home doesn’t have to cost much more than one built merely to code. At just $207 ft2 he’s achieved that, while also achieving his dual goal of historic design. In fact, many passersby comment on how well they’ve done fixing up their old home, when in fact, this newly built house was completed in 2014.
Why we like it: Bob and Kathy have hit a home run with this house. They have expertly crafted a “new old home” while demonstrating that a Net Zero design is not only attainable but a financially sound investment. This home, constructed with double stud walls with an additional layer of “out-sulation” and extreme care given to reduce thermal bridging, only costs them an average of $57 a month in electric bills, but this INCLUDES the charging of their two electric vehicles (estimated to be $40/mo.). Bob, who is very experienced in building energy consumption, estimates that the premium to move from “standard” construction to “high performance construction” is less than 9.5%.
Belfast, Maine: Deep energy retrofit 175-year-old farmhouse
EFFICIENCY: Renovations cut energy usage in half, with dramatically improved comfort.
FOUNDATION- Added 2” of closed cell spray foam to 2’-0” below ground (in the encapsulated basements and crawl spaces, R-13.
WALLS- most already insulated. Where added, R-12.
ROOF- Existing rafters in attic and attic walls were made deeper and filled with dense packed cellulose, R-39.
AIR TIGHTNESS- 11.88 ACH50 (Context is important, this represents a considerable improvement to this large, drafty, historic home).
HEATING AND COOLING- Phase one consisted of re-routing the distribution of the existing oil boiler’s distribution plumbing, phase two (now complete) consisted of installing a central wood pellet boiler system.
RENEWABLES: Wood pellet boiler
SIZE: 4,200 ft2 (5,300 ft2 gross)
COST: $50,000 (Excludes wood pellet boiler)
ENERGY/PERFORMANCE CONSULTANT: Evergreen Home Performance
DEEP ENERGY RETROFIT: Evergreen Home Performance
RENEWABLES: Maine Energy Systems
When Daisy and Angus Beal relocated back to Maine in 2014 after living in Vermont and Utah, they wanted a farm that would be home to not only their own young family, but also Angus’ parents and his aunt, who spends every summer with them. The 64-acre property they fell in love with came with a huge old house, providing plenty of room for this family of seven and their multigenerational living and farming plans. But its generous proportions were characterized by spendy oil heat, air leaks, and spotty insulation deficits.
They reached out to Evergreen Home Performance to help them save energy and money and improve the comfort in their house. The sheer scale of this 4,200 square-foot house featured prominently in the discussion of energy efficiency. They wanted the farmhouse to be energy efficient and affordable to heat for not only themselves but the next generation of farmers as well. They air sealed and insulated the entire house and basement and also expanded the available living space by insulating the rafter slopes in the attic, creating a quiet retreat space.
Prior to the retrofit (and before they purchased the property) the house was occupied by a single owner who turned the heat way down in most of the house and still reported an annual oil bill of $9,000 for heat and hot water. Post retrofit last winter, the three generation family heated the whole (and expanded) house comfortably and used half as much oil. The Beals took it a step further last year when they replaced the oil-fired heating system with a wood pellet boiler from Maine Energy Systems.
Why we like it: There are so many houses like this in Maine: big, beautiful, and in desperate need of an energy retrofit. Daisy, Angus, and Evergreen have shown us how to take a “big bang for the buck” approach. They took an honest scientific look at the existing house, its many energy flaws and prioritized a list of energy improvements. The result is a large, beautiful multi-generational house with improved comfort, quality and energy performance.
Peaks Island, Maine: Island cottage enters the 21st Century
EFFICIENCY: Estimated total energy costs of $1,800/year (includes home offi ce for two).
SLAB- New slab with 3” of XPS rigid foam insulation, R-15.
FOUNDATION- 1.5” XPS rigid insulation was added outside the concrete masonry wall and 1.5” rigid polyiso inside, R-18.
WALLS- Existing walls stripped to sheathing, wrapped with WRB, taped and sealed, followed by two layers of 1.5” polyiso rigid foam, a venting rain screen, and cedar shingle siding, R-19.5. ROOF- New sheathing, taped and sealed. 3.5” of spray foam applied to the underside and the remaining rafter cavities fi lled with dense packed cellulose, R-52.
WINDOWS- modest double pane windows were chosen, R-3.6.
AIR TIGHTNESS- 0.49 ACH50
HEATING AND COOLING- four ductless mini-split heat pump units (quantity needed for zoning) plus an electric heat mat in the 2nd floor bath.
VENTILATION- a high effi ciency energy recovery ventilator has been installed.
RENEWABLES: Plan to include in future
SIZE: 1,796ft2 plus two porches of 470 ft2
DESIGNER: Rachel Conly, Rachel Conly Design, LLC
BUILDER: Heather Thompson and Mark Pollard (lead carpenter), Thompson/Johnson Woodworks
ENERGY/PERFORMANCE CONSULTANT: Thompson/Johnson Woodworks and Rachel Conly Design blower door testing.
Both Will Crosby and his wife Kathy Simmonds had spent time living in Maine and dreamed of returning to raise their young family. But it wasn’t until they saw the house on Central Avenue on Peaks Island that they knew the time had come. Self-described “house people,” Will says it was the house that drew them here. And while at least one respected professional recommended tearing down the house and building new due to significant structural issues, to Will and Kathy this was simply not an option. They believe that buildings hold our history, and this is even more important in a small community like Peaks Island. Having grown up in an old house, it was important to Will to maintain the character of the house. So with the guidance of Thompson/Johnson Woodworks and Rachel Conly Design, they embarked on what some might consider a labor of love.
Aside from maintaining the original design and proportions, it was important to Will and Kathy that the house be low maintenance (it has a wood stove, but they don’t rely on it for heat) and convey a positive, friendly feeling. While they didn’t originally set out to conduct a deep energy retrofit, Will says that it is closely aligned with their values. And he credits Heather Thompson and Rachel Conly for artfully and consistently presenting them with opportunities to take the energy performance further throughout the project.
Why we like it: This is a highly detailed deep energy retrofit. The exterior was removed down to the existing sheathing and built out from there. The house was blower door tested with a reported 0.49 ACH50, which is below passivhaus levels and can only be achieved through remarkable diligence by the builders with regard to weatherizing and air sealing. This early 1900s house has been revived while preserving its architectural and cultural identity.