A neighborhood of super-efficient and affordable sustainable homes

By Heather Chandler
Photography by Katherine Sfeir

In 2015, Emily Ingwersen drove by the ramshackle motor court on Sea Road in Kennebunk and knew she’d found the spot. This unassuming site was the perfect location to build the neighborhood of high-performing homes that she and her husband, Rob Ingwersen of Ginger Hill Design + Build, had been planning.

The property had yet to go on the market, but a phone call from their realtor the next day informed them it would be going up for sale soon. They jumped at the opportunity and made an offer at their first meeting, not knowing exactly how it would all work out. But they trusted that between the location a half mile from Middle Beach, their background in building efficient, accessibly-priced homes, and a rebounding market, it would all somehow come together.

That hunch proved true. The first house was sold in July 2016, and within six weeks of the open house, the remaining three units were under contract.

The property – which sits in a neighborhood of seasonal and year-round homes – had originally housed a motor court that was operational in the 1950s and ’60s. In recent years, the two houses, two cabins and five motel rooms on the site had been used as housing for seasonal staffing for the area’s hotels and restaurants. The property had fallen into disrepair and, according to Emily, the town was eager to see some changes made.

While they could have petitioned the town to allow them to build nine units on the site, the Ingwersens opted instead to develop four homes, oriented in a courtyard layout. The units are almost identical, with 1,733 square feet, three bedrooms, two baths, and a large mudroom and pantry. They all offer a single floor design to blend into their surroundings and accommodate aging at home.

Of the four, two units are freestanding, and the other two are connected by a carport and garage, something that was required by fire codes. The homes are technically condominiums, though the condo association is controlled by the residents and functions more like a homeowner association. A modest $150 monthly fee covers plowing and road maintenance, lawn mowing and general landscaping.

INSPIRED BY MENTORS

Rob and Emily both grew up in the Kennebunk/Kennebunkport area and each has a background in the building trades. Rob began working as a carpenter as a teenager and continued through college. When he moved to British Columbia in his early twenties, he took a job as a lead carpenter and foreman for Peter Gosney, a builder who specialized in deep energy retrofits and high-efficiency new construction.

It was there that Rob learned about efficient building envelopes and double wall construction techniques, which were widely used in Canada as an answer to the extreme swings in the local climate. Rob credits Gosney with inspiring the building philosophy he employs today: “To be thoughtful not only in how materials [are] used, but in the design process and ... longevity and economy of a structure.”

Before he starts each project, Rob considers questions Gosney inspired: “Does the building have a simple roofline that helps keep costs down? Will long-term maintenance costs be burdensome to the future homeowner? Will utility bills be burdensome? Is the environmental impact of this home outsized?” It was this thoughtful approach that underlined the design of the Kennebunk project.

Like Rob, Emily was also exposed to building trades at a young age. Her father, from whom she learned basic building skills, was a builder and technical education teacher in Kennebunkport. An avid sailor, Emily studied marine engineering at sea and eventually received her captain’s license. She likens the experience of maintaining a ship’s system to that of maintaining a home. “On ships, things are efficient because they have to be, systems must all work harmoniously in order to avoid chaos. That same mentality can be transferred to houses pretty easily,” says Emily.

After working aboard sea vessels for many years, Emily accepted a land-based position at the Gulf of Maine Research Institute, managing facilities for their waterfront property. In 2014, she left to have her second child and ultimately joined Rob full-time in the business.

When I ask what drives their approach, Emily replies, “We are inspired by our desire to positively impact our community, including the people and environment. Our house was built on a shoestring. So, we recognize what it means to be on a budget. With a little creativity, you can build a beautiful, efficient home that is [also] affordable.”

The inspiration for their business name – Ginger Hill Design + Build – came from the family name, Ingwersen, which means “son of Ginger” in Danish. “It’s also a nod to the red hair that Rob inherited from his Scottish mother,” says Emily.

METHODS EMPLOYED

The Kennebunk project features air tight construction and a super-insulated envelope. To achieve this, they used 2x4, double wall construction and dense packed cellulose insulation in the walls, resulting in an R-value of 38 and significantly reduced thermal bridging. The ceilings were insulated with cellulose to an R-value of 60. The entire envelope and ductwork were meticulously air sealed. Eastern white cedar clapboards were installed over a ZIP wall sheathing system, creating a continuous air and water barrier.

Heating and cooling are provided by a ducted heat pump HVAC system with an integrated energy recovery ventilation unit. A propane fireplace provides back up heat in the event of a power outage.

They opted for Andersen 400 series casements and awnings, chosen primarily to accommodate the budget. “At the time, we felt they were a decent performing window at a reasonable price point,” says Emily. “Since then, more affordable triple pane windows have become more readily available and we are beginning to use [them] in new construction projects.”

Driven by an understanding of the environmental footprint new buildings create, the Ingwersens are committed to sourcing local, sustainable and non-toxic materials whenever possible. The ash flooring and Eastern white cedar siding came from Yoder’s Sawmill in Corinna, Maine. The siding is treated with Lifetime™, an all-natural wood preservative that Emily says will help the wood weather evenly over time “to a beautiful, natural golden gray.”

The roofs are a light-colored metal, selected to improve efficiency, reflecting the sun’s rays and keeping the homes cooler in the summer. All appliances are Energy Star™ rated. The cabinetry was custom built by New England Woodworks in Springvale.

THE PROOF IS IN THE PUDDING

The real test of a home’s performance is demonstrated by its energy testing and the actual energy costs incurred to live in it. To gauge the building’s air tightness, the Ingwersens brought in Clair Betze of BuildingWorks LLC to conduct a blower door test and energy analysis. Unit #1 came in at 1.76 ACH50, and received a 42 on the HERS index, making it 50% more efficient than a typical home built today.

The Ingwersens also installed a data monitoring system in Unit #1 so they could monitor temperatures and energy use throughout the year. They found that the home maintained mid-70s temperature throughout the summer without cooling and used HVAC only for limited amounts in wintertime.

From 2016 to 2018, this home was occupied by a young couple, one of whom worked from home, requiring a greater energy demand than a typical residence. During this time, total energy costs for heating and cooling ranged from $138/month in 2016 to $169/month in 2018, an amount that could be covered in large part by the addition of a modest 15-16 kWh solar PV system, making this home near net-zero for energy usage if solar is installed in the future.

THE NUMBERS ADD UP

The Ingwersens’ goal for the project was to create a neighborhood of super-efficient and sustainable homes priced in a range that was accessible for the average consumer, something that is not so easy to achieve when prioritizing efficiency, performance and sustainability (see Net-Zero subdivisions from our fall issue to learn more).

With selling prices in 2016 and 2017 that ranged from $350,000 to $380,000 ($202 - $219/sf ), including site purchase and prep, there is no question they were successful in creating a competitive price point for high-performing new construction, never mind the proximity to the beach. Those numbers have changed a bit in the years since, as the market has seen significant increases in construction costs.

The Ingwersens are currently working on a 10-lot subdivision of high-performing, super insulated homes in the woods of Arundel. The new project – which will include some improved efficiency measures including triple pane windows – is coming in at $220- $275 per square foot. If it’s anything like this one, we have no doubt we’ll be hearing a lot more about this up and coming design firm in the years to come.

Why we like it: Peer review by Chris Briley, CPHC, Leed AP, Briburn

The design possesses an understated elegance in its simplicity, materiality, energy efficiency and financial efficacy. Emily and Rob approached this project with confidence, determination and ingenuity. The home features common-sense R-38 double-stud wall construction, R-60 roof, a progressive ducted mini-split heat pump system with an integrated ERV, and locally sourced, environmentally friendly materials. Ginger Hill also incorporated a phase change material (PCM) supplied by Insolcorp in the ceiling under the insulation. This material is like a quilt filled with a careful blend of salts, clay and water designed to change state (from solid to liquid) at room temperature. In order to “melt,” the material needs to absorb energy from the conditioned space and can be credited with keeping the house cool in the summer.

DEFINITIONS by Dan Kolbert

THERMAL BRIDGE: A thermal bridge is any non-insulating material that extends from the interior to the exterior of the house. When you look up at a house after a light snow and see lines of melted snow going up the roof, you’re seeing the thermal bridging of the rafters, conducting heat directly through the wood from inside the house to the roof surface.
Likewise, if you had an infrared camera and looked at a standard house with 2x6 wall framing with fiberglass insulation, you’d see a bright red line at every stud. A well- built house will try to minimize this thermal bridging with thermal breaks - insulating surfaces that separate the interior from the exterior. Some methods for minimizing thermal bridges include double wall, Zip-R, exterior foam and Larsen trusses.

DOUBLE WALL CONSTRUCTION: There are several ways to accomplish double wall construction. The most common is to build the exterior walls exactly as you would with a “normal” house - either 2x4s or 2x6s, 16” or 24” on center, depending on structural and other concerns. Those walls will be weight-bearing.
Typically, the entire exterior, including roof, is framed first before going back and framing a second set of walls inside all the exterior walls. The distance between the two sets of walls will determine how much insulation can be installed, and thus the R-value of the wall.
A double wall is generally 10-12” thick. If both sets of walls are framed from 2x4s (which are 3-1/2” wide), that leaves 3-5” of clear space between the walls. That area in between is what provides the thermal break; continuous insulation that thermally separates the interior wall from the exterior wall, preventing a thermal bridge.

TECHNICAL SPECS

EFFICIENCY: 1.76 ACH50, HERS score-42
SIZE: 1733 sf
BUILDING ENVELOPE: Foundation—4’ frost wall/crawl space insulated with 2” rigid foam under the slab (R-10), 2” rigid foam on the walls (R-10) and spray foam on the rim joists and seams (R-21); Walls—2x4, double wall construction with dense packed cellulose, R-38; ZIP wall sheathing system; Ceilings—blown cellulose, R-60; Roof—cellulose to R-60; Windows—Andersen 400 series casements and awnings.
SYSTEMS: ducted heat pump HVAC system with integrated energy recovery ventilation; hybrid-electric heat pump water heater; propane fireplace provides back up heat in the event of a power outage.
RENEWABLES: none yet, 15-16 kW solar PV system predicted to make the project net-zero.
COST: $202/sf, includes site purchase and prep

TEAM

DESIGN/BUILD: Ginger Hill Design + Build
ENERGY SYSTEMS: Charlie Thomas, CGT Airsystems (ducted heat pump/ERV), Scott Nason Plumbing & Heating (heat pump hot water)
ENERGY TESTING: Claire Betze of BuildingWorks LLC

This article first appeared in the spring & summer 2019 issue of Green & Healthy Maine Homes magazine.
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