Grissom Lane Net-Zero Duplexes

2014-10-08 14.50.50Community Housing Partners (CHP), the largest affordable housing organization in Virginia, and a nationwide leader in energy efficient affordable housing, developed, designed and constructed these eight duplex apartments in Blacksburg, VA. Each of these apartments is capable of operating as a net-zero home. CHP, EarthCraft Virginia and Think Little will monitor the performance over at least 12 months in order to document net zero operation for EarthCraft’s new Net Zero certification. Think Little provided the works on this one: energy modeling, building envelope specs, HVAC design, PV system sizing, hot water distribution specs, and building commissioning.


Year built: 2014
Floor area: 929 to 966 ft2
HERS Index: -2 to +5 (varies with size of PV system)
Certifications: EarthCraft Virginia, Energy Star

Air-tightness: 0.09 – 0.11 envelope leakage ratio (2.0 – 2.3ACH50)
Walls: R-26, cellulose + 1″ DOW SIS foam board
Ceiling: R-60, blown-in cellulose
Slab: R-20, 4″ XPS foam board
Windows: PlyGem (U = 0.19-0.21, SHGC = 0.19-0.22)
Heating/cooling: 9kBtu/hr Fujitsu ducted heat pump (12.2 HSPF, 21.5 SEER)
Ventilation: Panasonic Whisper Green exhaust fan with passive air inlets
Water heating: A.O. Smith heat pump water heater
PV System: 3.5 to 4.1 kW per apartment

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