This project was designed and built on speculation by Meditch Murphey Architects.  The goal was to demonstrate that a market rate net-zero single-family home could be successfully developed and marketed in the Washington DC area.

The home was constructed on a previously developed site.  The existing dwelling was deconstructed rather than demolished, and the materials salvaged or recycled wherever possible.  Construction waste management was a goal throughout the construction process.

Bethesda Zero was designed to generate as much energy as it consumes on an annual basis.  We started with an ultra efficient envelop: 2x6 framing with 1.5" (R-7) rigid foam insulation on the exterior and a soy-based medium-density spray foam in the cavities - R-33 for the completed wall assembly. The room assembly varies between R-40 ad R-50 performance.  Windows and doors were double-glazed and protected against overheating by overhangs, pergolas and retractable awnings.  

After doing our best to reduce the heating and cooling loads, we spec'd HVAC equipment to provide those loads using as little electricity as possible. This includes a ground source heat pump and energy recovery ventilator.  The GSHP has a "desuperheater" that provides hot water extracted from the house in summer.  CFLs and LEDs throughout the house helps keep lighting and cooling loads small.  High efficiency appliances include an induction cooktop.

The energy loads from the house, already greatly reduced as described above, were matched using renewable energy systems, including a 9.5kW PV array and two solar-hot-water panels on the roof.

Water efficiency measures include low-flow fixtures (of course), but also a recirculation pump in an upstairs bath.  Rainwater is collected off the roof, stored in underground cisterns and used for irrigation.  Where rainwater capture was not practical, raingardens help keep stormwater on site.  Native plant species are used throughout the landscape to conserve water, shade the house, and provide habitat for wildlife.  

Bethesda Zero was certified Platinum under the LEED Homes rating system.