Project Subtitle:
Project Description:
We installed a zero energy modular home in Pine Tree Village, a manufactured home community in Carver, MA. The home was installed through the Zero Energy Modular Affordable Housing Initiative, a pilot program sponsored by the Massachusetts Department of Energy Resources. The home was built by Vermod, a modular builder based in Wilder, VT, and shipped to Carver. A rooftop solar PV system is scheduled to be installed summer 2021.
Building Type Summary:
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Occupancy Type and Details:
Owner-occupied, two adults live in the home full-time.
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Multiple buildings?:
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Site description:
The home replaces a manufactured home on the same lot, within an existing manufactured housing co-op.
Materials:
Interior finishes were selected for low VOC emissions. Resource efficiency is achieved in the factory setting, where waste is minimized by diverting usable cutoffs to subsequent homes.
Energy Highlights:
Thermal energy demand is managed with exceptional insulation and air sealing. Lighting and appliances are ENERGY STAR. The home uses no fuels. Annual electricity use can be met with the production of a rooftop solar system.
HERS Index:
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Electric Utility Company:
Datasets and Utility Bills sources and reliability:
Modeled consumption - Ekotrope
Modeled production - PV Watts
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Subslab assembly:
n/a - Insulated R-40 raised floor
Above grade wall assembly:
Above grade walls are 2x4 double stud, blown fiberglass fill
Frame floors on piers 9.25" TJI, 16" o.c., blown fiberglass with an R-value of 40.
Cathedral ceiling assembly:
SIP roof and insulated ceiling: 11.25" graphite EPS, R-59
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Process:
Developer identified home size and layout that would be most attractive to the low income families the ZEMAHI program serves. Home shape is driven by the size and shape of the building lot. Modular construction is preferred for quality and cost advantages as well as the minimal impact on the neighborhood of the infill construction.
Energy Modeling Software:
Ekotrope
Outcome of project goals:
The primary goal of the project was to make high quality, healthy housing available to low-income buyers. The high performance enclosure and zero energy mechanical systems contribute to the home being affordable to operate.
Even though this house was built as a spec home, it sold quickly. There is clearly a need for high quality, affordable housing.
Installation of the solar system was delayed due to supply chain and administrative slow downs, but the home is well on its way to having a full year of documented solar production.
Finances Description:
The home was developed by ZEMA, LLC. Total project costs were approximately $250,000, excluding land acquisition. A $20,000 incentive was provided by the Massachusetts Zero Energy Modular Affordable Housing Initiative. It was sold to an income- eligible buyer on the first showing.
Total Cost of Project:
Net Cost of renewable energy systems:
State incentives:
$20,000 MA Zero Energy Modular Affordable Housing Initiative
Utility incentives:
$1,300
Annual Electric Savings:
Published References:
This home was built speculatively as a model home. Official energy rating does not reflect rooftop solar system because the solar system was not installed at the completion of the home. As a model home, installation of the solar system was delayed to ensure the future owner would gain full net metering benefits. State renewable energy incentives and net metering rate are based on account holder income. As part of making new home ownership accessible to low income buyers, net metering compensation contributes to affordable total cost of ownership. The HERS index shown here reflects the solar system that was installed after the home was occupied.
Special architectural measures:
Small home size allows neighborhood density, minimizes landscape impact, materials and operation energy.
Energy Strategies:
A highly efficient structure is served by all-electric mechanical systems, efficient appliances and rooftop solar PV.
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Summary of enclosure strategy/description:
Exterior air barrier and superinsulation. Insulated floor, R-40, over sealed crawlspace.
Window Description:
Vinyl framed, triple-glazed casement windows. Kasson and Keller - manufacturer
Door Description:
Steel and foam door construction: full lite. Therma-Tru manufacturer
Mechanical Equipment Installation Details and Comments:
Ducted heat pump with ventilation coducted. Ducts are entirely enclosed within the pressure boundary of the home, within a soffit that runs along one side the length of the home.