General Energy Use, Strategies and Systems

Energy Use:

GFX G4-40 drain heat recovery system recovered heat from drain water in both showers. Efficiency is a measured 65% for a balanced flow plumbing arrangement at 1 GPM though center 4 inch copper tube and 1 GPM through the pre-heat helical copper coil tube. The GFX is currently not plumbed for balance flow and preheats only the cold water stream that flows directly into the hot water heater. As a result, when a mix of cold and hot is demanded at the shower, the center pipe flow is higher than the pre-heat tube flow and therefore unbalanced. The efficiency of the unit can be raised by replumbing to a balanced flow arrangement where the cold side water drawn at the shower head also goes though the GFX. The plan is to replumb to a balanced flow arrangement some time in the future to get the maximum efficiency and heat recovery.

Energy Strategies:

ZNE / DER Strategy
• Transition to all electric house
• Super insulate per DER rules
• Focus on energy efficiency
• Optimize floor plan without adding floor area to lower cost
• Recover space occupied by obsolete systems
• Remove chimney and two fireplaces
• Move top thermal boundary from attic floor to roof
• Employ full envelope insulation and super tight air sealing
• Use high R value & high solar gain windows
• Utilize heat pump based heating/cooling equipment
• Ventilate and recover waste heat with efficient HRV
• Recover shower drain water waste heat with heat exchanger
• Use induction stove, efficient appliances, LED & CFL lights
• Use roof mounted high efficiency PV to reach ZNE

Zero Net Energy Definition Used Site Energy Use

Monthly Energy Data and Utilities

Energy Data Type:
Electric Utility:
National Grid
Gas Utility:
Other purchased Fuels:


Datasets and utility bills sources and reliability:

Annual production value is metered and represents gross production from PV array.

Renewables and Energy Balance

Renewable Energy Sources:
Renewable energy is generated within the building footprint (e.g. solar PV on the roof)
Renewable Energy System Description & Details
PV is a 7.35 kW SunPower E19/245 3 x 10 array with Enphase M210 microinverters. This array was installed by New England Clean Energy and was officially connected to the grid and generating power on Jan 8, 2013. As of Aug 5, 2015, the PV array has generated 23633 kWh or 9148 kWh average per year over 31 months with no maintenance activities. For a one year period starting on Jan 8, 2014, the PV system generated 9103 kWh with 708 kWh sent to the grid and 8395 kWh sent to the house.
Annual renewable energy generated 9,103 kWh
Annual Renewable Energy Generated Data Type Measured
Renewable Energy System Type(s) Source of Annual Production Data
Photovoltaics Annual production value is metered and represents gross production from PV array.

Annual Energy Import/Export

Electricity amount (credited or exported to grid) 708 kWh/year