To-MAY-to, To-MAH-to, Pomegranate

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Or Net Zero Energy, Zero Net Energy, and Passive House

This home by Eco Performance Builders wouldn't qualify as a Passive House - but it's a net energy generator, and that's pretty cool!

This home by Eco Performance Builders wouldn’t qualify as a Passive House – but it’s a net energy generator, and that’s pretty cool for a spec home!

It’s good to see that some people recognize that a house built to code, as has been described as “the worst house I could legally build”, just isn’t good enough.

As some take small steps forward, others as taking big leaps. The Passive House1 crowd is building some pretty remarkable enclosures. (And often at some remarkably high prices, especially those with something like a million inches of sub slab foam2). There are some really innovative things happening there. I love this geeky stuff.

But I like the practical too. And Net Zero Energy may hold an upper hand. Yes, I know that Passive House and Net Zero Energy are not mutually exclusive. But some places, Net Zero Energy might be a lot more cost-effective than Passive House…and looking outside of just space conditioning, provide enough energy to keep the lights on,make toast, and power the big screen TV. Depending on your definition, it might be enough Net Energy Producer, and provide enough juice for the car, too, all for less than a Passive House. Where that’s the case, NZE deserves serious consideration.

I’m not talking “Net Zero Ready“, but Net Zero Already. Eco Performance Builders has proven this can be done cost-competitively and profitably with a spec home in the Oakland Hills in California. They built it. They’re monitoring it. It works! And very importantly from a market perspective, the buyers love it.

EPB NZE resultsEco Performance Builders did this with smart use of standard techniques and good attention to details rather than heroic measures. (Because this is California, and California likes to be different, this is called a Zero Net Energy home.) I’m hoping that Keith and Scott will give us a more in-depth article on the whats and hows soon so I won’t go too deep here. A very important point, though, is that performance data so far shows that it works. You’ll note they didn’t include gas consumption with the data…because there very purposefully isn’t any in this all-electric home. No gas lines run or gas service charges, either.

They didn’t stop with energy, either. Recognizing California’s water woes, they used smart piping design and low-use fixtures that combine to deliver water fast without the waste. Just like the comfort benefits that come with the energy details, that adds convenience and value to the homeowner.

Convenience. Comfort. Value. If we can deliver those, by any name, along with energy savings, we’ve got something that will make sense in the market. I find that encouraging.

1Yes, I know there are splits in the Passive House or Passivhaus community (or communities), but that’s beyond the scope of this short post!

2OK. I exaggerate. But 12″ is a lot. See http://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/do-we-really-need-12-inches-foam-under-our-slab for example.

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About the Author:

Mike Rogers is the President of OmStout Consulting. A nationally recognized expert in residential energy-efficiency, he works with contractors and programs to scale sustainable market approaches to improving homes. More on Google+

Comments

  1. Viana  March 27, 2015

    You do exaggerate. The article mentions 8″ to 12″ of insulation in Maine. Your article is about California. The company you mention puts tons of insulation too. Insulation is not a bad thing and without it you can not reach Net-Zero.

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    • Mike Rogers  April 18, 2015

      Viana, I’m a big fan of insulation! I like it in hot climates (see, for example, http://omstout.com/r-38-attic-insulation-is-all-you-need-in-phoenix/). I like it in cold climates (see, for example, http://omstout.com/musing-from-a-deep-energy-retrofit-the-spray-foam-standoff/). But 12″ of sub-slab insulation is a lot, even in Maine (I live in Burlington, VT with lower design temps and higher HDD than coastal Maine), and many folks think that is very far down the diminishing returns curve given the relatively small delta-T’s between the slab and the sub-slab soil. The money spent on say that last 6″ of subslab insulation could also be put to other uses…upgraded windows, PV panels, etc.

      Insulation is great. But other things are, too, and I think it’s perfectly reasonable for people to consider tradeoffs and their implications.

      reply

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