Southworth Retirement Residence

In 1986 my brother Harry and I started a building company, Garland Mill Timberframes, at our sawmill in Lancaster, NH.

Twenty years later, led by my son Ben, and with energy design help from Marc Rosenbaum, we began working with Jane Bindley to transform her lakeside home in Holderness into a net-zero residence. This remarkable woman was a delight to work with and the project was a success.

Janeʼs vision inspired us then and has continued to inspire our work to this day.

It was only a few years later that my wife, Nancy, and I started planning for a downsized retirement home to be built in a south facing field across the road from our mill. We agreed that if either of us lived to be ninety we ought to be in a home that one person could maintain alone.

The house was built to PassivHaus specs, again with help on the energy front from Marc Rosenbaum, and was completed in April of 2011. It is all one story with 1620 square feet of treated floor area.

Solar panels were added the next month. Their annual energy production exceeds the electric demand...and does so by a wide enough margin that if additional resistance heating replaced the woodstove there would still be a net excess. One very strong additional motive for installing 30 PV panels was to have electricity available to power an electric vehicle. So far, our two year average excess of 4,000 KWH would suffice to drive an EV about 10,000 miles, which it soon will do.

Nancy wanted a simple modern aesthetic. With Benʼs help this was achieved in a variety of ways. Materials were local, often salvage, always simple. White cedar cladding. Soapstone counters. White pine timbers from our mill. Beech floors. Plaster walls. Galvanized steel roof. Windows with plaster jam returns. For the big glass, maple sills were made from a blow-down at a local sugar orchard. Modern Danish wood stove.

Flooring installed to the plaster walls with no baseboard trim.

The completed project has satisfied all the points on our original wish list. As the home owner I can say that now, after all these years in the house, if we were to do it all over again we would build it just the same way.

Quick Facts

General

Location
361 Garland Road
Lancaster, NH03584
United States
Building Type
Project Type Zero Energy
Basis of Performance Claim Modeled,
Bedrooms
Conditioned Floor Area 1 986

Energy Summary

Energy Data Type
Renewable Energy System Type(s)
Ratings
Annual renewable energy generated 8 182

Envelope and Mechanicals

Subslab assembly

Foundation - There is no slab. A hardwood floor is fastened directly on ¾” advantech which in turn is fasted to 2X4 sleepers over 12” of salvage polyisocyanurate foam insulation (R-55), above a vapor barrier and 30” of compacted sand. The four foot foundation frostwall is insulated from the inside with 3” of rigid insulation board (polyiso) that makes direct contact with the wall insulation (dense packed cellulose). There is neither basement nor crawl space.

Foundation wall assembly
Above grade wall assembly

The bearing exterior wall is 2X4 construction covered (going outward) with 1/2” plywood then 2” of rigid polyiso foam insulation then tape and rain drain then horizontal strapping and finally 3/4” white cedar vertical siding. A second 2X2 wall was built 12” inside the building and gusseted to the 2x4 wall with ½” plywood gussets. It is nonbearing and rests on the subfloor (advantec) which was held back to allow the polyiso subfloor insulation to be in direct contact with the dense packed cellulose wall insulation that was blown in between the two walls. The wall R-factor is calculated at R-49 for 12” of cellulose plus 2” of polyiso. This effort was to assure continuous thermal isolation and is compromised only by the gussets and the window and door bucks.

Door Assembly

ThermoTech Fiberglas Fenestrations

Air Changes per hour, ACH50 0.65

Project Team:

Other Team Members:

Ratings:

Awards:

Completion

Completion Date:

Scope

Type of Construction
Number of buildings
Floor area of each building
Bedrooms
Stories
Conditioned Building Volume 13 950
Conditioned Floor Area 1 986

Location and Climate Details

Address
361 Garland Road
Lancaster, NH03584
United States
Location Type Rural
Climate Region Zone 6
Köppen Climate Type Dfb
Lat. / Long. POINT (-71.475812 44.4710847)
Elevation 390
Solar Insolation 4.52 kWh/m2/day
Annual CDD and Base Temp 521 | 75
Annual HDD and Base Temp 8458 | 68

Site

Site Conditions:

Site Description:

Monthly Energy Data and Utilities

Energy Data Type: Modeled,

Electric Utility: Public Service of New Hampshire

Gas Utility:

Renewables and Energy Balance

Renewable Energy Sources:Renewable energy is generated within the building footprint (e.g. solar PV on the roof),

Renewable Energy System Description & Details:

Annual renewable energy generated 8 182
Annual Renewable Energy Generated Data Type
Power Rating 7Watts
Renewable Energy System Type(s)
Source of Annual Production Data

Walls and Roof

Subslab assembly

Foundation - There is no slab. A hardwood floor is fastened directly on ¾” advantech which in turn is fasted to 2X4 sleepers over 12” of salvage polyisocyanurate foam insulation (R-55), above a vapor barrier and 30” of compacted sand. The four foot foundation frostwall is insulated from the inside with 3” of rigid insulation board (polyiso) that makes direct contact with the wall insulation (dense packed cellulose). There is neither basement nor crawl space.

Subslab R-value 55.00
Slab edge assembly
Slab edge R-value
Foundation wall assembly
Foundation wall R-value
Above grade wall assembly

The bearing exterior wall is 2X4 construction covered (going outward) with 1/2” plywood then 2” of rigid polyiso foam insulation then tape and rain drain then horizontal strapping and finally 3/4” white cedar vertical siding. A second 2X2 wall was built 12” inside the building and gusseted to the 2x4 wall with ½” plywood gussets. It is nonbearing and rests on the subfloor (advantec) which was held back to allow the polyiso subfloor insulation to be in direct contact with the dense packed cellulose wall insulation that was blown in between the two walls. The wall R-factor is calculated at R-49 for 12” of cellulose plus 2” of polyiso. This effort was to assure continuous thermal isolation and is compromised only by the gussets and the window and door bucks.

Above grade wall R-value 49.00
Cathedral ceiling assembly
Cathedral ceiling R-value

Windows and Doors

Window Assembly:

ThermoTech Fiberglas Fenestrations

Door Assembly:

ThermoTech Fiberglas Fenestrations

Average window U-factor 0.19
Door U-Factor
Door Area

Mechanical Systems

Space cooling - Manufacturer & Model
Space heating - Manufacturer & Model
Domestic hot water - Manufacturer & Model 80 sqft of solar collector, 120 gallon Vaughn stone lined tank with electric resistance backup.
Domestic hot water - capacity
Ventilation - Manufacturer & Model Zehnder ,
Lighting Manufacturer and Model
Lighting Efficiency
Mechanical Equipment Installation Details and Comments

EPA certified wood stove (Morso from Denmark) with dedicated combustion oxygen for primary heat. 2250 watts of electric resistance heating for backup: five 450 watt ECO wall mounted heaters each with its own thermostat. No mechanical cooling. Full window sun shades on the south facing windows.

Envelope

Air Changes per hour, ACH50 0.65
Air Changes per hour, CFM50

General Process

Imagining ourselves as ninety-year-olds making up a wish list, we listed the following goals:

Always warm...and with lots of light, too

Handicap accessible

No basement

No electric bill

Neither furnace nor fuel tank

Almost no lawn mowing

Entire garden in raised beds just outside the kitchen door

Single car garage

Unpainted cedar siding

Guest room with bath doubling as DVD “away” room

Studio/workshop

Design for Adaptability:

Software Tools

Software Tools:

General modeling information:

Lessons Learned

Outcome of Project Goals:

Discrepancies:

Rebates and Financial Incentives

Federal incentives
Local incentives
State incentives
Utility incentives
Other incentives
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