"The Groton" Model

Project Subtitle: 

23 Coppersmith Way, Townsend, MA

Project Description: 

 “The Groton” is an 1835 square foot home Transformations, Inc. built and sold in the Coppersmith Way development in Townsend, MA.  It was started in late 2009 and completed in June of 2010.  This home is a second generation Farmhouse model with a garage under to fit the sloped site.  Many of the energy efficiency features have been honed in on though cost effective evaluations and input from many in the building science field.

The shell and energy efficient features of this home are highly repeatable.  Transformations currently over 100 homes in the development and building pipeline with similar zero-energy specifications.

The cost to get to zero energy has been brought down to $3 per square foot over a stretch code home with a leased PV system.  At these prices, the zero energy homes can spread fast throughout Massachusetts and other states with Solar Renewable Energy Credits.  It is Transformations goal to help speed this process.  The typical home saves about 60% of its energy in the shell, appliances, lighting, hot water, etc.  The other 40% or more is made up though the PV. 

The Groton features a 7.14 kW PV system that is integrated into the surface plane of the roof for a pleasing aesthetic.  We attained the look of BIPV without the cost!  The roof under the PV system was recessed 8” inches to accomplish this.  Black framed mono-crystalline panels further this curb appeal. 

A Navien 180 instantaneous gas fired hot water heater was used in place of any solar thermal systems.  It did not take up any roof space, cost $1,800 to install (as opposed to $8,500 for a solar thermal system) and used only about $43 worth gas over a 12 month period (36 Therms).

The ventilation system used was a Fantech 1504 Heat Recovery Ventilator.  We exhausted the three bathrooms and supplied fresh air to the hallway on the second floor.  This was done at less than half the price of the LifeBreath systems we used previously.

This “Groton” model home was cost effective to build, has excellent curb appeal and is vastly repeatable and scalable. It was built on speculation and sold for $359,900.  The positive energy produced was about 1450 kW hours a year.  This is enough energy to supply a plug in Prius a modest commute, 5 days a week, 50 weeks a year.  With homes like these, we can solve the carbon emissions of the building sector and start to work on the transportation sector as well!

Building Type Summary: 

single-family residence

Address: 

23 Coppersmith Way
Townsend, MA 01469
United States

Elevation: 

280

Lat. / Long.: 

POINT (-71.6882359 42.6666999)

Location Type: 

Suburaban

Köppen Climate Type: 

Dfb

Climate Region: 

Zone 5

Solar Insolation: 

3.75 kWh/m2/day

Annual HDD : 

6430

Annual CDD: 

969

HDD Base Temp: 

65 F

CDD Base Temp: 

65 F

Occupancy Type and Details: 

The home was occupied for the 12 month period except for 10 days of vacation. There are 2 members in the household.

Number of stories: 

2

Conditioned Floor Area: 

2 699

Multiple buildings?: 

Total number of units in project (all buildings): 

1

Total floor area of project (all buildings): 

2 699

Historic?: 

Completion date: 

Tuesday, June 1, 2010

Energy Highlights: 

The shell and energy efficient features of this home are highly repeatable. The cost to get to zero energy has been brought down to $3 per square foot over a stretch code home with a leased PV system. At these prices, the zero energy homes can spread fast throughout Massachusetts and other states with Solar Renewable Energy Credits. It is Transformations goal to help speed this process. The typical home saves about 60% of its energy in the shell, appliances, lighting, hot water, etc. The other 40% or more is made up though the PV.

Electric Utility Company: 

Unitil Gas and Electric

Gas Utility Company: 

Unitil Gas and Electric

Datasets and Utility Bills sources and reliability: 

source of the data is utility metering. Net electricity consumed including the gas w/conversion is -1574 kWh

Net electricity usage (purchased electricity): 

-2 510

Natural gas amount (purchased energy): 

936

Subslab assembly: 

2" rigid, R-10

Slab edge assembly: 

2" rigid, R-10

Foundation wall assembly: 

3.5" closed cell foam, R-20

Above grade wall assembly: 

12" open cell foam, R-46.8 cavity

Flat attic assembly: 

18" cellulose, R-67

Space heating - Manufacturer & Model: 

2 Mitsubishi mini splits, MSZ-FE12NA indoor units, MUZ-FE12NA outdoor units

Space cooling - Manufacturer & Model: 

2 Mitsubishi mini splits, MSZ-FE12NA indoor units, MUZ-FE12NA outdoor units

Domestic hot water - Manufacturer & Model: 

Navien 180, 98% efficient

Ventilation - Manufacturer & Model: 

Fantech 1504 HRV

Process: 

The shell and energy efficient features of this home are highly repeatable. Transformations currently over 100 homes in the development and building pipeline with similar zero-energy specifications.

Finances Description: 

Cost of building construction, excluding design fees, site preparation, and unconditioned space was $160,299. The square footage of the conditioned space, measured from the exterior is 2,699 square feet. This includes the conditioned basement but not the garage. The cost per square foot, including the PV system was $59.39.

This “Groton” model home was cost effective to build, has excellent curb appeal and is vastly repeatable and scalable. It was built on speculation and sold for $359,900.

Total Cost of Project: 

160 299

NESEA Awards: 

NESEA Zero Net Energy Building Award 2013 runner-up

Energy Strategies: 

The Groton features a 7.14 kW PV system that is integrated into the surface plane of the roof for a pleasing aesthetic. We attained the look of BIPV without the cost! The roof under the PV system was recessed 8” inches to accomplish this. Black framed mono-crystalline panels further this curb appeal.

Energy Use and Production Documentation: 

Subslab R-value: 

10.00

Slab edge R-value: 

10.00

Foundation wall R-value: 

20.00

Above grade wall R-value: 

46.80

Flat attic R-value: 

67.00

Average window U-factor: 

0.20

Solar Heat Gain Coefficient: 

0.26

Cost per square foot of Conditioned Space: 

59.39

Scope Description: 

Area of conditioned space is measured from the exterior.

Site conditions: 

previously undeveloped land

Renewable Energy Sources: 

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

Window Description: 

Windows U-value of 0.20, SHGC of 0.26

Project Team: 

Team Member: 

Carter Scott

Status: 

Live

Zero Net Energy Definition Used: 

Source Energy Use

Basis of Performance Claim: 

Verified

Type of Construction: 

New

Renewable Energy System Type(s): 

Photovoltaics

Renewable Energy System Description & Details: 

Utility only provides net usage. See utility bills for supporting data. (42) Suntech 170 watt mono-crystalline panels in black frames; (1) Solectria PVI 3000 inverter and (1) Solectria PVI 4000 inverter Peak power rating is 7.14 kW Projected annual production is ~8,000 kilowatts per year.

Annual Renewable Energy Generated Data Type: 

Measured

Source of Annual Production Data: 

metered by utility

Space Heating - Efficiency (e.g., 92 AFUE): 

HSPF 10.6

Space Cooling - Efficiency (e.g., 16 SEER): 

HSPF 10.6

Submitter Contact Email: 

Submitter Contact Phone Number: 

(978) 597-0542

Project Type: 

Zero Energy

Lighting Manufacturer and Model: 

Compact florescent

Weight: 

0