Net-Zero Energy in New Hampshire

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Lubberland’s Edge sits above a marshy estuary, a sanctuary for wildlife. With its many windows, the home is designed to maximize appreciation of flora and fauna, and provide a cozy, energy-efficient nest for its inhabitants.
The west side of the home sports the main entry and a screened porch, both amply shaded from the hot summer-afternoon sun.
Large, triple-pane, low-e windows maximize efficiency, solar gain, and the expansive views. A concrete slab floor provides thermal mass for storing passive solar gain.
The main living area is angled slightly southeast from the main structure. Excess solar gain is controlled seasonally by large eaves.
The open, modern living space defies the farmhouse-style exterior. The well-insulated, passive solar home rarely requires supplemental heat from the wood heater.
The large east windows gain morning light for quick warm-ups on winter days, while the west side is shaded, and protected from afternoon overheating.
The kitchen takes advantage of energy-efficient technologies, including an induction cooktop. The range hood is ducted through the HRV.
Second-story clerestory windows keep the landing well-illuminated, naturally.
Water-efficient fixtures in the bathroom also provide some energy savings.
Twelve-inch-thick, double-stud walls were filled with cellulose for an insulation value of R-45. Ceilings are insulated to R-70; the floor is insulated to R-26.
The Whirlpool Hybrid Care dryer, which has a heat pump, doesn’t require an external vent.
The Zehnder ventilation system, from left to right: ComfoFond L Eco 550 ground-loop-based preheater; ComfoAir 550 energy recovery ventilation unit; and ComfoCool 550 cooling unit.
The PV modules and DC optimizers during installation.
The 7.6 kW SolarEdge StorEdge inverter.
System Costs Installed Cost: $16,822 Less Incentives, Rebates, Tax Credits: $3,750 state rebate and $5,046 for the 30% federal tax incentive Net installed cost: $8,026
As of mid-November 2016, the system had produced almost 14.5 MWh.

For homeowners Norbert and Robin Wesely, morning at their Lubberland’s Edge home involves live entertainment—on the wild side. With saltwater marshes, freshwater wetlands, and intact blocks of forest just outside the door of their new net-zero-energy home, its native residents—birds and mammals—put on a show.

The couple moved into their 1,900-square-foot retirement dream home in December 2015. The energy-efficient home is located on Lubberland Creek in Newmarket, southeastern New Hampshire.

“We enjoy being in nature and hoped to build a home that did as little to disrupt the natural balance as possible,” says Robin. “The windows allow us to observe the deer, turkeys, birds of prey, fox, and bobcats without disturbing them.”

Designed by Kaplan Thompson Architects and built by Futuro Construction, this innovative home features energy-efficient technologies, passive solar design, and exceptional views. The end result is a net-zero-energy home that offsets all the energy it uses with a rooftop PV system—and it offers remarkable comfort, requiring very little upkeep.

Maximum Gain

Heating this northeastern home without relying on fossil fuels became a major focus, and it primarily uses the sun. The home’s long axis sits along an east-west orientation and has lots of south-facing windows to take advantage of the sun’s rays throughout the heating months, while offering stunning views of the creek and wetlands.

The polished concrete floors on the first floor provide thermal mass to absorb, store, and then gradually release the sun’s heat when indoor temperatures dip during the night or on cloudy days. During the winter, the sun sits lower in the sky, and sunlight streams in through south-facing windows. In the summer, when the sun is higher in the sky, a 4-foot-deep overhang blocks sunlight from entering directly. The home’s open floor plan and an energy recovery ventilator help circulate the air for even temperatures throughout.

Passive House Standard

Although Lubberland’s Edge isn’t certified as such, it was built to the Passive House standard, meeting its criteria for energy use and airtightness. Passive House Planning Package computer modeling was used to examine the impact of different design modifications on the home’s energy consumption. This software also helped the architects estimate the required size of the PV system needed to be a net-zero energy consumer.

To minimize heat loss, generous amounts of insulation were used. The home features double-stud framing that results in 12-inch-thick walls. Insulated with dense-pack cellulose, these walls are rated at about R-45. Because the studs are spaced apart, this construction method also minimizes thermal bridging.

The roof sections have two different constructions—the pitched truss roof is insulated with loose-fill cellulose to R-70, while the lower roof is 5-inch-thick structural insulated panels on 14-inch I-joists with 1 inch of spray foam insulation and full-depth dense-pack cellulose, also for R-70. The interior slab-on-grade was insulated with 6 inches of rigid expanded polystyrene for R-26.

The home was constructed with durable materials and methods, for lower maintenance costs. A continuous air barrier helps eliminate condensation, promoting durability. The metal roof is designed to last 40 to 70 years. The home features two different types of siding. The bleached, oil-dipped cedar shingles should last 50 years or more, and the James Hardie cement siding has a 35-year product warranty and a 15-year warranty on the finish.

Comments (2)

Christopher Yaun's picture

Excellant choice. Heather and I live in a similar house in Portsmouth finished in 2008. We use less than 1/5th the energy of an Energy star home. The passive house is extra comfortable. There are no drafts. Because walls are super insulated they do not suck heat from your body. Because dry outside air is not drafting through the house it is easy to keep the humidity higher. That combination of higher humidity and no draft means we are comfortable at lower air temps. The passive house is an excellant solution.

solarKings's picture

Very nice article, but for the 25YR solar PV system, I would have gone with a decentralized power topology which offers complete reliability and true fault-tolerance using Enphase microinverter technology. Centralized solar solutions, even with power optimizers, still contain a single point-of-failure which can disable the entire solar PV solution for an unknown period of time. Not optimal.

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