The Power of Zero starts with a definition of what they mean by Net Zero Energy:
The International Living Future Institute (ILFI) defines Net Zero energy (NZE) as "One hundred percent of the projects energy needs being supplied by onsite renewable energy on a net annual basis." In one simple, elegant sentence, a radical agenda for eliminating carbon dioxide emissions and use of combustion fuels within the built environment is set in place. In short: generate what you use.
But alas, it is not so simple and elegant. In fact, it's complicated. Because while lead author Brad Liljequist gets philosophical and metaphoric, with paragraphs titled living within your means and thou shall not steal and a penny saved is a penny earned, quoting Moses and Ben Franklin, he neglects Aesop, whose ant is busy putting away supplies for winter.
"Why bother about winter?" said the Grasshopper; we have got plenty of food at present." But the Ant went on its way and continued its toil. When the winter came the Grasshopper had no food and found itself dying of hunger, while it saw the ants distributing every day corn and grain from the stores they had collected in the summer. Then the Grasshopper knew:
It is best to prepare for the days of necessity.
This has always been my fundamental problem with Net Zero, because of that "net annual basis" wording in the simple, elegant sentence, because they are not fundamentally prepared. They make hay when the sun shines, but at night or when winter comes are forced to depend on the kindness of strangers who have been standing by all year with the generating and distribution capacity to keep the lights on in winter when the days are short.
That's the downside, listed up front because that's where the clichés and aphorisms are. Now let's look at the upside: It's really hard to get to net zero energy without designing for serious energy efficiency, with energy consumption reduced by 50 to 80 percent. So all of the projects in the book are extremely efficient, using far less energy than conventional buildings. They have more insulation, better windows, are carefully sited because they are all trying to cut their energy consumption down low enough that their rooftop solar panels will be able to generate enough to balance out over the course of the year.
And they are lovely projects, from new houses to restorations of old houses to office buildings, many of which we have shown on TreeHugger. Many of these buildings have also been built in accordance with the Living Building Challenge, the wonderful certification system (also from the International Living Future Institute) that looks at a lot more than just energy, so they are healthy buildings that deal with water and food and waste and are fabulous models of what we should be building. The book presents them beautifully and thoroughly.
The Living building Challenge is perhaps the most interesting and challenging building certification system around, and being net zero energy is one of its petals. However this book has not disabused me of my thinking that the Net Zero standard on its own is not. As I have noted before, rooftop solar disproportionately favours those who have roofs. So it works better for low rise structures and suburban development.
The only relatively high building is the Bullitt Center in Seattle, and its solar panels actually hang out beyond the property line over public rights-of-way because they didn't think they had the rooftop area to do it all on site. This is not a happy precedent.
Finally in Part IV, the authors address the problems, even discussing the "duck curve" problem (where utilities have more capacity than they can use mid-day and have to ramp up really fast to deal with evening loads). They note optimistically that because Net Zero certified buildings are so much more efficient,
"that net zero energy buildings can be easily designed to use power at their time of peak production. A benefit of highly efficient building envelopes is that they retain cold and heat for longer periods of time. ...A net zero building that is well designed to use power when it is produced, with a small amount of storage for the fuel uses that must happen during dark periods such as lighting and enertainment systems, will have little demand on the grid."
And that is indeed the future, when we have storage like Tesla's Powerwall, combined with super-efficient houses and offices that don't use much energy at all. That is the end that we are looking toward.
The problem with Net Zero is that it confuses the means with the end. Fundamentally the goal should be to use less energy and get off fossil fuels. Net Zero Buildings do use less energy because it is the means to its end of being net zero. You could do the same thing by adding more solar panels or buying more efficient ones as they come onto the market. It is biased toward low density and low rise In a time when we have to be promoting the opposite. And most importantly, it depends on that big electric utility standing by to deliver when the sun doesn't shine.
Aesop's ant knew that it had to plan for winter, with lots of food in a well built and secure place. That's what we need too: seriously efficient buildings that use very little energy, and that are part of a larger resilient community that supplies cheap green energy to everyone, whether they have nice big roofs or not. The book acknowledges this in its chapter on Net Zero Communities, but these are larger discussions about more than electricity, the basic focus of Net Zero Energy buildings.
The subhead of The Power of Zero is "learning from the world's leading net zero energy buildings." But the examples they show also happen to be mostly brilliant and gorgeous Living Building Challenge certified buildings. The real world of Net Zero is a lot bigger, a lot uglier, and a lot more problematic.