Positive Energy Downsizing Case Study: BPC Green Builders’ Innovative Approach

At BPC Green Builders, we’re dedicated to sustainable home construction. In 2019, we completed a net-zero contemporary dream home in Trumbull, Connecticut that showcases our commitment to innovative design, advanced building science principles, and sustainable, low-carbon construction strategies. This project, our second for the same couple, highlights their trust in our expertise and dedication to sustainable living. Our clients' journey with BPC Green Builders began with their first home—a much larger residence designed to accommodate children and parents. However, as their needs changed they returned to us for a downsizing project. Keep reading to learn how we transformed their vision into a positive energy home that not only meets their current needs, but also sets a new standard for energy efficient living.

 

The Challenge: Downsizing with Enhanced Efficiency

When our client returned to us for their second BPC Custom Green Home, there were several specific requirements that put our green building expertise to the test: 
  • Design a smaller home (approximately 3,700 square feet) that surpasses the efficiency of the previous near Net Zero Energy home we built for them in 2014
  • Create a space that allows the homeowner to live entirely on the main floor with additional guest and recreation areas
  • Maximize energy efficiency while providing panoramic views of the landscaped property
  • Achieve positive energy status, including electric vehicle charging 

Custom Green Home Solutions: Advanced Building Science in Action

We have over 25 years of experience collaborating closely with homeowners, architects, engineers, energy raters, vendors, and subcontractors across Connecticut and adjoining areas of New York state. This, combined with our building science and sustainable construction knowledge, enabled us to successfully bring our clients’ vision to life. 

Superior Thermal Envelope

We implemented a robust strategy to minimize the home's energy demands by creating assemblies that effectively control heat transfer. This approach keeps the home comfortable year-round while significantly reducing energy costs.
  • Foundation - We used 8 inches of rigid foam insulation under the concrete slab and 4 inches at the edges, creating a well-insulated base for the home.
  • Walls - We constructed the exterior walls using wider 2x8 studs, allowing for a thick blanket of cellulose insulation. We then wrapped the entire house in 3 inches of continuous mineral wool insulation, to prevent excessive heat loss through the wall framing (thermal bridging).
  • Roof - We filled the 14-inch engineered roof rafters with dense-pack cellulose and then placed 4-inch structural insulated panels (SIPs) above the rafters to increase the overall R-value and eliminate any possibility of condensation within the assembly.. 
  • Air Sealing - We used high-performance acrylic tapes at all joints to create an exceptionally airtight envelope, preventing unwanted air leakage.

Cutting-Edge Mechanical Systems

We installed state-of-the-art systems that work in harmony with the thermal envelope to maintain comfort while minimizing energy consumption. These advanced systems are key to achieving the home's positive energy status.
  • Heating and Cooling - A Mitsubishi 3-ton electric heat pump powers three separate air handlers, allowing for precise temperature control throughout the home:
    • One 1.5-ton air handler for the first floor
    • Two ¾-ton air handlers, one for the primary suite and another for the lower level
  • Ventilation - A Zehnder ComfoAir 350 system provides fresh, filtered air to living spaces and bathrooms, ensuring excellent indoor air quality while recovering heat from outgoing air.
  • Hot Water - A Sanden Eco2 electric heat pump water heater with a high-efficiency rating (COP of 4.5) provides domestic hot water using a fraction of the energy of traditional water heaters.
This combination of efficient heating, cooling, ventilation, and hot water systems works together to create a comfortable living environment while keeping energy consumption to a minimum, contributing significantly to the home's positive energy performance.

Thoughtful Design Elements

The design features elements that enhance both sustainability and livability:
  • Open plan layout on the main floor with a gourmet center island kitchen
  • Large windows at the living room's southern exposure to capture solar gain for free heat
  • Vaulted red cedar plank ceiling, wood beams, and white oak flooring throughout the first floor
  • Decorative concrete floors at the walkout finished basement level
  • Custom heavy timber staircase with glass railings
  • Extensive landscaping using ledge stone recovered from ledge removal
  • Triple-glazed aluminum-clad doors and tilt/turn windows with U-values of 0.16 (roughly R-6)

Proactive Problem Solving

During initial excavation, our team uncovered an unexpected groundwater issue that could have posed serious long-term problems for the homeowners. Rather than depending upon typical foundation waterproofing and footing drain details, we designed and implemented an innovative "river that runs through it" drainage system beneath the foundation, effectively redirecting and controlling the water flow.  This proactive solution not only demonstrates our commitment to quality construction but also our foresight in preventing future moisture-related issues, ensuring the home's long-term integrity and the homeowners' peace of mind.

Project In Process

Beyond Net Zero: A Positive Energy Home

A positive energy home is one that generates more energy than it consumes, making it a remarkable achievement in sustainable living. This home not only meets its energy needs through a robust solar array but also accommodates the charging of an electric vehicle that traveled roughly 22,000 miles in the first year of ownership.  Our innovative approach to sustainable building earned this home a 2020 DOE Housing Innovation Award in the Custom Home category, recognizing our commitment to excellence in design and efficiency. Additionally, the home holds numerous green certifications and standards, including:

BPC Green Builders: Setting New Standards in Sustainable Construction

Our comprehensive process involves collaboration from pre-design through construction. We help clients understand green building approaches, work closely with architects on material choices and systems, and manage every aspect of the build. Our unique Green Warranty guarantees comfort, energy efficiency, and compliance with stringent performance standards. At BPC Green Builders, we know that building a sustainable home is a collaborative effort. By engaging with homeowners and architects, we create living spaces that are environmentally responsible, healthy, comfortable, and tailored to each client's needs.

Learn more about BPC Custom Green Homes today. Call (203) 563-9909 or contact us online to get started. 

Finished Project