UPDATE 2013: We’ve moved! The Stow House is still AWESOME, it just has a new owner enjoying it!
Where? Stow, MA
When? Completed June 2010
What? Almost Passivhaus, almost net-zero energy, 2.5 floors and a basement 30’x22′ interior dimensions. 6.9 KW PV installation
– Architect: Kraus Fitch, Amherst MA
– Builder: Transformations Inc, Townsend MA
– Passive House Energy Modeling in PHPP: DEAP Group, Newton MA
– House Monitoring: Fraunhofer CSE, Cambridge MA
– IAQ monitoring; Plug-in-load monitoring: Lawrence Berkeley National Laboratory, Berkeley CA
HERS Index: 9 (though I have noticed the size of the PV array and some of the insulation levels are wrong in the report, so probably quite a bit lower)
Energy-Star-Homes: Tier III (June 2, 2010)
PHPP: “Specific Primary Energy Demand” 36.8 kBTU/sqft/yr
Blower Door: 180 CFM50. 0.71 ACH50 (using PassivHaus volume) 0.50 ACH50 (HERS volume)
Climate — HDD: ~7300 base 68 for Worcester MA
Actual 1 year results (6/2010-5/2011): 10,000 KWh site energy used. 8,300 KWh site energy produced. 1,700 KWh net used. I believe our electricity bill for the entire year for EVERYTHING (including lawn mowing!) was $400. And that’s not even for net metering — Hudson Light and Power pays one back for electricity going to the grid, but not at the same price you pay for taking, so even on a month where we make more than we use, we usually have an electricity bill unless it is WAY off, like a sunny August where we are away for 2 weeks.
30 panels x 230W/panel = 6.9 kW installation.
Canadian Solar CS6P-230W panels with M-190 Enphase microinverters. As it turned out, on many days a year — usually spring — the sun was bright enough and the temps cool enough that we would clip at 199W per panel and the system would be pegged at ~5.96 KW. But it wasn’t usually very much that it clips. Like maybe the panels could have made 205W per panel for a few hours mid-day. Maybe because the 230W panels were performing more like a 235 or 240 panel? But it’s still maybe the case that the added cost of the more expensive/heavy microinverters would never have been worth it in both cost or larger footprint. So no regrets.
In the news
New England Cable News reported on our house back on Mar 25, 2014