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What is Net Zero Energy’s endgame?


March 9, 2015
By Anthony Capkun


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March 9, 2015 – Perhaps the ultimate display of high-performance housing of the future is the Net Zero Energy (NZE) home, but what are the ramifications, truly, in terms of sustainability?

“The technology for NZE homes is here, and the concept appears to meet with general enthusiasm,” said Wrighthaven Homes’ Steven Wright (photo at bottom, far left). “If you’re already a high-performance builder, going NZE won’t change much.”

Energy-efficient home certifier EnerQuality recently hosted a full-day “EQ Housing Innovation Forum” that explored current and future green residential construction innovation, with an eye toward high-performance (HP) housing. Wright was one of the panelists in an NZE discussion moderated by Sonja Winkelmann (director of CHBA’s NZE Housing Council).

He went into details over his own foray into NZE housing with an abode he constructed in Elora, Ont., that is fully off-grid capable with 8kW solar PV generation and two days-worth of energy storage.

But there’s a catch with this home and, one might infer, all NZE homes: they require a power backup, just in case. During this cold 2014/15 winter, the Elora house has had to turn to the public electricity grid for extra capacity from 9 pm until 10 the following morning.

Plus, as a matter of course for those just-in-case moments, NZE homes also come equipped with a standby generator.

There are some additional nuances with NZE homes, like figuring out how to get hooked up for net metering, or homeowner education, as there is a lot of technology involved—most of which the average homeowner knows very little to nothing.

And then there’s the cost: NRCan’s CanmetEnergy study into NZE Housing suggests it “is not yet market-feasible due to the large first cost of achieving it ($100,000 to $150,000)…”.

I found myself wondering… added costs aside, were a number of homes to be built or retrofitted to NZE specs, what would happen to the public electricity grid? At what point does the distribution system become too expensive to operate? Costs are kept down (or manageable, anyway) because they are shared across numerous homes and businesses, but what happens when the non-NZE homeowner becomes the exception, not the norm? Would he be able to afford the delivery of electricity? Would he be forced to convert to NZE? Who will help him pay for it?

Or will he, like the NZE homeowners around him, invest in a generator, only use it for primary power rather than emergency power. If that’s the case, then how will NZE homes (which already come equipped with fossil-fuelled backup generators) help curb our appetite for gas or diesel?

“Clearly, the development of Net Zero Energy housing is most promising within the context of sustainable neighbourhoods and communities…” writes CanmetEnergy, but I’m not so sure.

— Anthony Capkun is the editor of Electrical Business Magazine, and can be reached at acapkun@annexweb.com .