Home that has been retrofitted by King Pine Homes

Background Information

  • Neighborhood: East Bayside, Portland, ME

  • Built: 1860

  • Square Feet: 863

  • Basement: Full

  • Beds/Baths: 2/2

  • Condition: Poor

Original Condition and Performance

King Pine Homes purchased this property in the summer of 2015. The house was in need of numerous energy upgrades and a whole house remodel. For example, the shingles, sheathing, and plaster walls were all deteriorated and crumbling. In addition, there was knob and tube wiring and leaky cast iron pipes. The heating system, installed in the 1970's, was in equally rough shape requiring immediate replacement.  

Worse yet, insulation and air sealing were virtually non-existent. Large cracks and holes were visible to the naked eye, as the shingles had shrunken over time and the sheathing was comprised of a mishmash of old boards. With no insulation in the walls or basement, and very little in the attic, the house was tough to heat considering its small size.

Original sheathing of home on Fox Street in Portland, MEOriginal sheathing 2 during retrofit by King Pine Homes on Fox Street in Portland, METhird image of original sheating during Retrofit by King Pine Homes in Portland, ME

Retrofit Process

The retrofit was part of a complete home renovation and remodel that required our contractors to completely gut the house down to the studs. As the home was rebuilt, the following energy upgrades were incorporated:

  • Removed old gas boiler, water pipes, and baseboard radiators. Installed two new mini-split heat pumps with an electric baseboard system to serve as a backup. 

  • Removed outdated electric water heater and installed a new heat pump electric water heater (40 gallons). 

  • Installed 2.85 kW photovoltaic solar array on the roof.

  • Installed new zip system sheathing and roof decking. 

  • Sealed basement slab.

  • Blew in spray foam insulation along basement walls (R15).

  • Built double stud walls in the interior of the house to increase wall cavity depth; blew in dense-packed cellulose into wall cavities (R25). 

  • Blew in spray foam insulation alongside rigid board insulation in attic eves; used dense-packed cellulose in slopes (R40). 

  • Installed new ENERGYSTAR-rated windows (U factor 0.33, SHGC 0.35) and insulated fiberglass doors.

  • Wired in all new LED light fixtures. 

  • Purchased new ENERGYSTAR-rated appliances. 

  • Installed Panasonic Whisper Green bathroom exhaust fans.

Finished roof decking by King Pine Homes for a retrofit job done on Fox Street in Portland, MEHeat pump installed by King Pine Homes on Fox Street in Portland, ME during a complete energy retrofitSolar array installed on a home on Fox Street in Portland, ME
Roof Sheathing and insulation after a retrofit by King Pine Homes on Fox Street in Portland, MESpray foam in the basement of a retrofit done by King Pine HomesCellulose insulation in the kitchen after a retrofit done by King Pine Homes


Energy auditors from Rook Energy Solutions analyzed and tested the home once construction was completed. Using their thermal imaging cameras, they confirmed there was no thermal bridging throughout the building. A blower door test was done and measured 890 CFM at 50 pascal (0.28 air changes per hour), which represented an 84.5% reduction in air leakage.

The heat pumps, which serve as the primary heating and cooling source for the home, are expected to consume 3,512 kWh per hear. Domestic hot water is projected to use another 2,004 kWh, appliances 290 kWh, and lighting 285 kWh. The total anticipated electrical load for the home is 6,092 kWh per year. On the production side, the 2.85 kW solar array on the roof will generate 4,056 kWh per year, offsetting 67% of the home's consumption. 

Retrofit Costs

At King Pine Homes, we're interested in figuring out how much it costs to take an ordinary home and turn it into a "pretty good" home. And by this, we mean a home that is well-built, energy-efficient, comfortable, and has healthy indoor air. To figure out the price tag for this transformation, we've attempted to identify what a "base-level" remodel would cost. We then compare it with our actual retrofit costs. The figures below represent the difference between the products used in a base-level remodel and the high-performance products we used.

Energy Efficiency

$15,000 - Insulation (including double stud walls);

$5,000 - Air sealing;

$1,500 - Windows and doors;

$6,400 - Mini-split heat pumps; 

$1,300 - Heat pump water heater;

$350 - ENERGYSTAR appliances; and

$500 - LED light fixtures.

$30,050 - Subtotal

- $3,000 - Efficiency Maine Rebates

$27,050 - Total Cost

Estimated Payback Period: 7.1 years

Renewable Energy (Solar)

$11,400 - Upfront cost for 2.85 kW system

- $3,420 - Investment Tax Credit 

Total: $7,980

Estimated Payback Period: 22.4 years