Net-Zero Energy in New Hampshire: Page 3 of 3

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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.

Smart Layout

Norbert and Robin like the floor plan and layout of Lubberland’s Edge. “We knew what we wanted going into the process and consequently didn’t go through a lot of iterations during the design phase,” explains Robin. “We like to entertain and have found this to be a great property for that. The open floor plan, with the living room, dining room, and kitchen area together, makes the most of the space. If the weather is nice, we’re outside or in our screened-in porch.”

The vaulted ceilings in the living and dining rooms, 11-foot ceilings on the second floor, and plentiful windows give the home an expansive feel without adding square footage. To minimize the heating and cooling load of the home, the exercise room, storage, garage, and mechanical room are all outside of the home’s envelope. This keeps garage fumes and airborne pollutants from entering the living space.

Active Energy from the Sun

Because Norbert and Robin wanted to live in a net-zero home that uses no fossil fuels, the PV system was sized to produce all of the energy the home uses for heating, cooling, cooking, water heating, and plug loads. The south-facing rooftop was the ideal location for the grid-tied 7.7 kW system. The roof’s steep pitch (45°) is good for maximizing the system’s production in the winter.

As soon as the roof and the electrical panel in the garage were in place, the PV system was installed to offset energy used during construction. The PV system’s energy production has been much greater than the estimates, especially in the summer. During August 2016, it was about 25% greater than forecast. The system’s power optimizers are helpful, since the array is partially shaded by trees to the west.

Harmony Energy Works designed the system for compatibility with the Tesla PowerWall by using the SolarEdge 7.6 StorEdge inverter, for future battery backup. The system also includes monitoring capabilities, so both Harmony Energy Works and the homeowners can keep an eye on the PV’s system production.

Norbert and Robin have created a unique retirement home. They appreciate that Lubberland’s Edge offsets it energy use with solar. This also helps protect the surrounding ecosystem that they cherish. “It’s a really special home that integrates numerous innovative technologies,” explains Norbert.

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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