Benker Residence: A Net Zero Energy Home
Project Background and Services:
The Benker Residence, built by Glastonbury Housesmith, achieved net zero status while meeting an array of sustainability benchmarks. Steven Winter Associates, Inc. (SWA) provided third party verification services for this multiple award-winning residential project.
Energy Conservation Measures:
Proving that resiliency and efficiency go hand in hand, the project met 2012 IRC wind loads while using advanced framing techniques. 5 1/2” blown-in batt (R24) plus 2 ¾” mineral wool (R11) over ZIP sheathing yield a total wall thermal performance of R35. Roof rafters were insulated with closed cell foam plus blown-in batt (R58) and the aluminum roofing meets ENERGY STAR requirements. The Thermomass foundation system includes R20 continuous extruded (XPS) foam sandwiched in the concrete wall pour, and R17 foamglas was used under the slab. Orientation specific glazing optimizes passive solar performance: north-, east-, and south-facing windows use a high Solar Heat Gain Coefficient (SHGC) of 0.36, while west-facing windows use a low SHGC of 0.16. All windows are triple-pane, argon-filled, aluminum clad wood with U-values between 0.23-0.26.
A closed loop geothermal system does triple duty for the home, providing heating, cooling, and pre-heat for domestic hot water. A heat pump water heater delivers DHW after the pre- heat and occupancy sensors “call” for the hot water before fixtures are turned on (a requirement for DOE Zero Energy Ready Home and Water Sense). Our performance testing for multiple green/energy certifications revealed tight ducts (0 leakage to outside, 2.5% total leakage) and a tighter envelope (0.57 ACH50 air infiltration). A dedicated Venmar Eko ERV with a MERV 13 filter provides fresh air to the super-tight home. Lighting is 100% LED and efficient appliances feature a heat pump dryer and induction cook top. The final HERS Index was 29 prior to PV and –23 after the 13.8 kW PV system mounted on tracking poles. For both belt and suspenders, a Secure Power Supply functionality allows the homeowner to access 4500 watts of power from the PV system if the grid goes down.
Awards:
This residence was the First Place winner of the 2014 Connecticut Zero Energy Homes and the RESNET 2015 Cross Border Challenges. It also won a CTGBC Residential Award of Merit.