2016 Challenge Participant:

BPC Green Builders - Ranade Residence

Applicant: Mala Ranade

Project Address: 83 Stonecrest Road, Ridgefield, CT 06877

Bdrms./Sq. Footage: TBD

Builder Website: www.bpcgreenbuilders.com

Project Overview Project Specifications Project Team Project Photos
The BPC Green Builders - Ranade Residence project in Ridgefield, CT.

General project overview:

Mala and Kishore Ranade had lived in Ridgefield for many years. When they became empty nesters, they decided to build a new home in the same town that would accommodate their new lifestyle and desire to live in an energy efficient green home. They purchased an older ranch-style house close to town, up on a hill with a great view. Mala and Kishore then turned to BPC Green Builders to help them achieve their goal. BPC has been building high performance, energy efficient homes for sixteen years and welcomed the opportunity. BPC introduced them to Elizabeth DiSalvo of Trillium Architects, a local business that specializes in green homes. Trillium came up with a spectacular contemporary design for the home that utilized the existing foundation, saving the homeowners money and reducing the new materials required to build the home. BPC and Trillium worked together to create details for the thermal envelope and mechanical system that greatly reduced the operational energy required to run the home. In fact, the solar PV system generates enough electricity for a net zero energy profile, with a final HERS score of -1.

Special Features:

  • Wonderful views across the ridges of Ridgefield

  • Open concept floor plan

  • Single-level living potential for the future

  • Natural gas fireplace that can heat the entire house in the event of a power outage

Orientation and Envelope: (windows, insulation, framing)

  • House roof is oriented to solar south for PV system.

  • Home energy Rating Scored (HERS) score of -1, denoting net zero performance.

  • Blower door result of 0.73ACH50 nearly achieves PH standard of 0.60ACH50.

  • Existing basement slab was covered with vapor barrier and then insulated with 4” of EPS foam board.

  • Existing concrete block foundation walls were insulated with 2” of 2lb spray foam. Then a 2x4 wall was framed to the interior and insulated with 3.5” of dense-pack cellulose.

  • Exterior walls sheathed with ZIP R-sheathing (OSB mated to a 1” sheet of polyisocyanurate rigid foam board insulation,) to reduce thermal bridging.

  • Exterior walls framed with 2×6’s at 24” spacing, insulated with 5.5” of 1/2lb SPF (R-26 exterior wall assembly, including ZIP-R sheathing).

  • 14” I-joist rafters (for reduced thermal bridging) filled with 3” of 2lb spray foam insulation and 11” of dense-pack cellulose (R-60)

  • Wall and roof sheathing air-sealed with European acrylic flashing tapes.

  • European triple-glazed windows with u-values of 0.26 (roughly R-4).

  • Fiber cement siding installed over drainable weather resistive barrier.

Heating, Cooling, and Hot Water:

  • Air source heat pump with wall-hung interior units in each room heats and cools the house

  • Condensing, natural gas, tankless water heater provides instant hot water with no storage losses


  • An energy recovery ventilation system provides a carefully calculated supply of fresh air to maintain high indoor air quality. The ERV does double duty as it also is used for bathroom ventilation.


  • PurePoint Energy designed and installed the 11.45 kW roof mounted solar electric system for the home. The system consists of two sub arrays that were installed on the two best roof sections for solar production. The equipment consists of 35 of the SunPower E327 watt panels and two of the SMA Sunnyboy string inverters. The SMA inverters are able provide a combined output of 3,000 watts during a grid outage while the sun is shining. The system is expected to produce around 15,000 kWh annually.

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