A Case Study

First Home in Green Acres Achieves Zero-Net Energy Usage for First Full Year of Occupancy

David Shepler, the first resident of Green Acres, tracks the daily performance of his home. He moved in on March 27, 2009, and below you can see his energy performance and comments. David has agreed to share his home’s energy performance regularly for the interest of all those curious about the performance of our homes and zero energy concepts more broadly. Check out our video page for more on David’s experience with his home at Green Acres.

Characteristics of David’s home:

  • Size: ~3,000 Square Feet
  • Energy Production: 10 kW Photovoltaic System
  • Other Energy Features: Geothermal HVAC (Ground Source Heat Pump), Insulated Concrete Form (ICF) construction, high-performance windows, and heat-recovery ventilation.

Performance for the first full year of occupancy:

  • The home over-produced a net of 1,490 kWh when taking the total electricity (-1,733 kWh) and propane consumed in the home’s gas range (8.9 gallons of propane consumed on site = 243 kWh of electricity).
Full-Year Net Solar Production - Shepler Home

Comments from David:

  • The dark red line references the Net Consumption axis on the right. This shows that the house continued to produce electricity faster than it could consume it until 11 Oct 09, when consumption through the winter months began to turn the line around. The house built up an electricity “reserve” of 3,704 kWh. Through early March 2010, the house gave back back over 2,200 kWh because of some persistent snow cover on the panels and cold temperatures. But soon after the 8 Mar 2010 reading from Central Hudson Gas and Electric (CHGE), the home began once again to over produce electricity! By the end of the first full year of occupancy, the home over-produced 1,733 kWh of electricity.
  • I also saw the effect through Oct and Nov of leaving a tree at the southeast corner of the house, which brought significant shading in the morning hours. I decided on 12 Feb 2010 to take the tree down, and I noticed an increase of a few kWh daily.
  • Note: The only other fuel consumed on site was 8.9 gallons of propane for a gas cook range.  According to the Northeast Sustainable Energy Association (NESEA), 8.9 gallons of propane translates to 242.66 kWh, resulting in an effective net home energy production of +1,490 kWh.