Transformations – 8 Cavite St

In April of 2009, searching for a way to showcase sustainable housing, the Commonwealth’s MassDevelopment put out a Request For Qualifications for developer/builders to design and build single family and multi-family homes at its Devens, Massachusetts residential community.  The purpose of the project was "to provide a replicable example of current and innovative sustainable building practices that are practical for Massachusetts homes.  In keeping with the Governor's stated goal of moving toward zero net energy development, a goal of the project is to provide a forum for development of zero net energy, or near zero net energy, moderately-priced housing".

Transformations, Inc. was chosen to build the single family project with a total of 8 homes.  In the summer of 2011 we began construction on the first two homes.  The first home was sold by October.  By the following October in 2012 all of the homes were either sold or under agreement.  We had planned on a 3.5 year build out.  The combination of zero energy homes and the great Harvard public schools seemed to be a potent combination.

The final HERS indexes have ranged from HERS 6 to -37.  This home represents one of over a 100 zero energy attainable homes in the Transformations development and building pipeline—a sure sign of replicability in the Northeast!

The home starts with a double studded frame wall that is 12 inches thick for a R45.6 cavity insulation level.  The attic has 18" of cellulose (R-63), the basement walls have 3 1/2 inches of closed cell foam (R-20), the basement slab and slab edge has 2" of rigid (R-10) and the window are triple pane (R-5).  The super insulated shell allows for a simple Mitsubishi mini split of each of the two floors. And first floor master bedroom. The hot water heater is a 98% efficient Navien unit.  The flat portion of the roof faces towards the South and has a 17.28 kW PV system installed on it.  After accounting for propane use for hot water, the homes net positive energy production for the year was 15 kWh. 

The Devens project has been a resounding success on many levels.  These homes met the goals of the MassDevelopment program.  They sponsored two zero energy home workshops to help get the word out to other builders and developers. The Department Of Energy extended the Building America Program for Building Science Corporation to continue our work together.  Transformations was pleased with another model community designed and built to advance energy efficient construction in the Northeast.

Quick Facts


8 Cavite St
Devens, MA01434
United States
Building Type
Project Type
Basis of Performance Claim
Conditioned Floor Area 3 000

Energy Summary

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

Envelope and Mechanicals

Subslab assembly

2" rigid

Foundation wall assembly

3.5" closed cell foam

Above grade wall assembly

12" open cell foam, R-45.6 cavity

Door Assembly
Air Changes per hour, ACH50

Project Team:

BuilderTeam Member: Carter Scott

Other Team Members:




Completion Date: Monday, October 1, 2012


Type of Construction
Number of buildings
Floor area of each building
Conditioned Building Volume
Conditioned Floor Area 3 000

Location and Climate Details

8 Cavite St
Devens, MA01434
United States
Location Type Suburaban
Climate Region Zone 5
Köppen Climate Type Dfa
Lat. / Long. POINT (-71.6066957 42.5443287)
Elevation 250
Solar Insolation 4.39 kWh/m2/day
Annual CDD and Base Temp 321 | 75
Annual HDD and Base Temp 6861 | 68


Site Conditions:

Site Description:

Monthly Energy Data and Utilities

Energy Data Type:

Electric Utility:

Gas Utility:

Renewables and Energy Balance

Renewable Energy Sources:

Renewable Energy System Description & Details:

Annual renewable energy generated
Annual Renewable Energy Generated Data Type
Power Rating 17Watts
Renewable Energy System Type(s)
Source of Annual Production Data

Walls and Roof

Subslab assembly

2" rigid

Subslab R-value 10.00
Slab edge assembly

2" rigid

Slab edge R-value 10.00
Foundation wall assembly

3.5" closed cell foam

Foundation wall R-value 20.00
Above grade wall assembly

12" open cell foam, R-45.6 cavity

Above grade wall R-value 45.60
Cathedral ceiling assembly
Cathedral ceiling R-value

Windows and Doors

Window Assembly:

Door Assembly:

Average window U-factor 0.20
Door U-Factor
Door Area

Mechanical Systems

Space cooling - Manufacturer & Model Mitsubishi mini split,
Space heating - Manufacturer & Model Mitsubishi mini split,
Domestic hot water - Manufacturer & Model Navien
Domestic hot water - capacity
Ventilation - Manufacturer & Model Panasonic ,
Lighting Manufacturer and Model
Lighting Efficiency
Mechanical Equipment Installation Details and Comments


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

General Process

Design for Adaptability:

Software Tools

Software Tools:

General modeling information:

Lessons Learned

Outcome of Project Goals:


Rebates and Financial Incentives

Federal incentives
Local incentives
State incentives
Utility incentives
Other incentives