Net Zero Energy Home, Westport, CT

I had the privilege to work on a Net Zero Energy home in Westport from 2015-2016

The house was completed in the summer of 2016. The 6000 SF house was designed by the owner. My firm, Rountree Architects helped  fine tune the design and was responsible for all the construction and engineering drawings. The contractor was BPC Green Builders of Wilton, CT

The house was conceived of and designed to be a “Net-Zero Energy” (NZE)

home from the beginning. The client had a clear focus on this as he had already built a NZE home in Vermont and was extremely satisfied with it.

To be considered a “net zero energy home”, the total amount of energy used by the home and it’s occupants on an annual basis must be roughly equal to the amount of renewable energy created on the site. So far, this house has achieved that.

Most of the home’s energy demands are met by a 10.7 kW solar PV system as well as solar heat gain through south facing windows.

The house has a super-insulated envelope on all 6 sides and as a result, a very low heating/cooling load.

The average electric bill is $20!!

Some of the energy related features of the home include:

  • Double Wall construction
  • R-56 wall insulation (High R – Zip Sheathing, 3” closed cell foam and 7.5” dense-pack cellulose)
  • R-84 attic insulation (24” cellulose)
  • R-36 under-slab insulation (8” EPS Boards)
  • Triple Pane UniLux tilt-turn windows
  • Continuous air barrier
  • 14” open-web floor construction
  • Ducted air source electric heat pump by Mitsubish
  • Stiebel Eltron electic Heat pump water heater
  • Zehnder heat recovery ventilation system (whole house)
  • 72 kW PV system (32 – Sunpower 335 modules with Solar Edge Inverters)
  • Sealed combustion, direct vent, gas fireplace (Spark Fire Ribbon)
  • Recessed LED lighting throughout

 

10.72 kW Photovoltaic (PV). 32 Sunpower 335 watt modules with SolarEdge inverter with PV optimizers. The PV system was activated in January of 2017 and after approximately 9 months, the owner reports that his utility bill averages between $19 and $22 (which is the standard service charge). His system is consistently over producing and he is banking those credits against future bills.

 

The house received a HERs rating of 11, which means it is 89% more efficient that a typical house of the same size

SolarEdge inverter

Mitsubishi Compressor

Mitsubishi Air Handler

Stiebel Eltron heat pump water heater

Zehnder Heat Recovery ventilator (HRV)

Zehnder HRV supply and return ducts