new hampshire's
     sustainable energy resource

Heather Parker

Site Address 101 Mill Pond Way, Portsmouth, NH 03801

Google Map of Address
Please note that Google Maps of some properties may not be accurate. Please be sure to also use the directions provided below.

Region Seacoast

Construction Cost $200/sq.ft.

Year Built 2009

Year of PV Choose

Window brand Serious Materials (aka Alpen)

This new house at 101 Mill Pond Way, Portsmouth NH, was designed to be as energy efficient as possible, as well as use sustainable materials and processes. The expectation is that the 1937 sq-ft house’s annual heating bill will be a few hundred dollars, about a tenth of a new conventionally well-built house.

Highly insulated, air-tight, designed to maximize solar energy, the house stores passive solar energy, has solar-thermal flat-plate collectors with an 80-gallon domestic hot water tank, and has a grid-tied 3.4 PV system. A Rinnai sealed-combustion propane fireplace on the first floor supplies heat. Roof pitch is 45 degree, better at our 43rd degree latitude for solar panels.

The house faces south east with the majority of windows on the south, most of which are large fixed units, so less perimeter heat loss and no air infiltration. South-facing window area is about 12% of total house square-foot area, excluding the windows in the separate sunroom. There are no windows on the north. East and west windows are smaller and placed to maximize ventilation. Triple-pane argon-filled, fiberglass-framed windows have Heat-Mirror glazing (U .2 or approximately R5; windows are reflective or receptive to solar gain, depending whether it is placed on north, south or east and west. Cellular window shades add more insulation as needed.

The house has a SFPF (shallow frost-protected foundation) and a slab, which passively stores solar energy in the winter. Ridge foam insulation wraps from the eves down the outside and under the slab, resulting in less thermal bridging and air infiltration:

A plastic vapor barrier on the second-floor celing was caulked at all edges; above the sheet rock is almost 2 feet of blown-in cellulose (R70). Six-inch wall studs are 24 inches on center, with sprayed-in damp cellulose (R42, with outside foam insulation). The outside finish is EIFS (Exterior Insulation Finish System); four colors of stucco were used to add interest.

A garage on the north side blocks wind. A sunroom on the south can be closed off from the main living space, so heat gain in summer is reduced and the space is kept cooler at night in winter for plants. The main entry is on the north and contains the laundry, which has an outside vent for the electric dryer, and that room can also be closed off from the main living space.

Openings to the outside were minimized whenever possible. Insulated ductwork in the attic connects to a heat-recovery air ventilation system that reduces humidity and exchanges fresh for stale air continuous in winter, as well as manually at bathrooms all year. There are no other exhaust fans in the three bathrooms, nor is there a kitchen exhaust fan. The induction stovetop and small oven are located near a kitchen window that can be opened if needed. While propane is used in the fireplace, it is a sealed combustion unit with dedicated outside air supply built into its exhaust vent. Backup hot water is electric so no need for venting.

TJI framing, cellulose insulation, bamboo floors, stained concrete floors, Trex deck, recycled marble counters, recycled glass tile, stucco exterior, induction cooktop, very small microwave and halogen oven, no chimney, FPSF (frost-protected shallow foundation: no basement), all Energy-Star appliances, solar hot water, heat recovery air exchanger

From the center of Portsmouth, at the intersection of Congress St, Middle St, Islingston St and Maplewood Ave, head north on Maplewood for .4 miles. Take a left onto Dennett Street and go .2 miles to Mill Pond Way. 101 is the third house on the right. Park along the street please. From Maine, get on the Rte 1 Bypass south to NH, cross the Sarah Lawrence Bridge (middle bridge): Take the first exit after the bridge in NH, take a right, off the ramp onto Maplewood Ave, then take the third right onto Dennett St., go .2 mile to Mill Pond Way. 101 is the third house on the right. Park along the street please.