Green Zero Carbon Home

Project Subtitle: 

Renovation of 1970's house to a zero carbon footprint

Project Description: 

We cut the carbon dioxide emissions of our 5300sf 1970's house by 43 tons per year getting us to a year round zero-carbon footprint. We are not only  saving money, our bills (for heating oil and electricity) are down $11,500 a year, but we are earning a 15% return on our investment. That's 15% after tax and with no volatility. Much better than my stock and bond investments! For more information, check out

Building Type Summary: 

single-family residence

Other Awards: 


Note that HERS index and Energy Star score are only available on new construction this is a renovation. There are no awards that I am aware of that apply to renovations. Perhaps you should start one? Since 99% of the US housing stock is already existing successful retrofits are important to publicize. Especially those that make money. None of your case studies shows the investment or return. In fact your case studies make no mention of money and therefore a reader cannot tell if this makes financial sense for them.


119 Farm St
Dover, MA 02030
United States



Lat. / Long.: 

POINT (-71.328383 42.225533)

Location Type: 


Köppen Climate Type: 


Climate Region: 

Zone 6

Annual HDD : 


HDD Base Temp: 


Number of stories: 


Conditioned Floor Area: 

5 300

Unconditioned Floor Area: 

2 600

Multiple buildings?: 

Total floor area of project (all buildings): 

5 300


Completion date: 

Thursday, March 1, 2018

Site description: 

Gentle slope, mostly wooded


All wood was FSC certified
All paint was zero VOC

Energy Highlights: 

15kW roof mounted solar PV system
2 Bosch 5 ton ducted heat pumps
Triple-glazed windows
Extra insulation
Heat pump hot water tank

Annual renewable energy generated: 

15 000

Power Rating: 

15 670Watts

Electric Utility Company: 


Gas Utility Company: 


Datasets and Utility Bills sources and reliability: 

Annual heating oil data is 100% accurate for delivery records. Daily use is from gauges on the oil tank and is not as reliable. It is pretty good if averaged over about 5 days.

Electricity data is from Eversource bills and an Efergy whole house meter. It is 100% accurate.

Solar power data is from the Solar Edge reporting system and has been audited to the net-metering credits on my Eversource bills

Electricity amount (imported from grid): 

10 000

Electricity amount (credited or exported to grid): 

15 000

Net electricity usage (purchased electricity): 

10 000

Natural gas amount (purchased energy): 

5 000

Subslab assembly: 


Above grade wall assembly: 

2x4 walls with fiberglass insulation, approx R12

Space heating - Manufacturer & Model: 

Bosch 5 ton heat pumps (2)

Space cooling - Manufacturer & Model: 


Domestic hot water - Manufacturer & Model: 

State heat pump hot water tank

Domestic hot water - capacity: 



We did it ourselves after a lot of research

Energy Modeling Software: 

My own spreadsheets. I created model of our house that has a R-squared of 80% to the actual energy use of the house.

Outcome of project goals: 

We got to a zero carbon footprint, zero utility bills and are making a 15% return on investment

Finances Description: 

All paid in cash

Total Cost of Project: 

75 000

Gross Cost of Renewable Energy System: 

75 000

Value of Tax Credits for renewable energy systems: 

50 000

Net Cost of renewable energy systems: 

25 000

Federal incentives: 

30% federal tax credit on solar panels, about $23,000

State incentives: 

MA SREC2 solar power subsidy, about $29,000

Utility incentives: 

$1500 utility rebate on heat pumps

Annual Electric Savings: 

2 500

Annual Revenue from SRECs or other renewable energy credits: 

3 750


Get all the incentives and the low cost, or zero interest, state loans. Get Massive to pay for the insulation.


Claims are based on my own detailed tracking of electricity use, solar electricity generation and heating oil use. I have daily spreadsheets for over a year detailing this but heating oil use was measured by me reading the gauges of our oil tanks and there is no utility documentation.

NESEA Awards: 


Subslab R-value: 


Foundation wall R-value: 


Above grade wall R-value: 


Average window U-factor: 


Solar Heat Gain Coefficient: 


Visible Light Transmittance: 


Cost per square foot of Conditioned Space: 


Number of Bathrooms: 


Scope Description: 

Renovation. Added triple glazed windows. Added R10 insulation to roof and R38 to basement.

Site conditions: 

preexisting structure(s)

Renewable Energy Sources: 

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

Other Purchased Fuels Description: 

Heating oil

Summary of enclosure strategy/description: 

renovation of existing 10"x2" joists on flat roof

Roof R-value: 


Window Description: 

Loewen triple glazed patio doors. R4 on lower floor R 5 on upper floor.

Number of Bedrooms: 


Project Team: 

Team Member: 

David Green



Zero Net Energy Definition Used: 

Site Energy Use

Type of Construction: 

New - still under construction

Renewable Energy System Type(s): 


Annual Renewable Energy Generated Data Type: 


Source of Annual Production Data: 


Days per year Building is fully occupied: 


Submitter Contact Email: 

Submitter Contact Phone Number: 

(617) 872-3559

Project Type: 

Zero Energy

Lighting Manufacturer and Model: 

LED light bulbs