The phrase Net-zero energy or Zero-carbon has always troubled me. I have noted that I can make my tent net-zero energy if I have enough money for solar panels, but that’s not necessarily a sustainable model. Others have been troubled by the concept as well; Passive House consultant Bronwyn Barry writes in the NYPH blog: " I’m betting that our currently mythical ‘Net Zero Energy Homes’ – however one defines that empty integer – will be buried in a marketing graveyard somewhere."
Bronwyn continues:
Rooftop solar disproportionately favors those who have rootops, preferably big ones on one-story houses on big suburban lots. Those people tend to drive a lot.
© Bronwyn Barry
If we are going to work our way out of this crisis we are going to have to live closer together in walkable communities in buildings that don’t use much energy per capita, and that doesn’t leave a lot of roof per capita for solar collectors.
© Margaret Badore
(Although TreeHugger’s Margaret Badore visited a building yesterday that could prove me wrong)
Flickr/CC BY 2.0
I was thinking about this issue yesterday after Michael Graham Richard wrote his post Game-changer: Rooftop solar will be at grid parity in all 50 U.S. states by 2016- How in fact does this change the game? Are people who can’t put solar on their roof now going to pay more for power than those who can? Does the game-changer disproportionately favor suburban sprawl?
© Elrond Burell
Coincidentally, a lot of my questions about the quest for net-zero were answered by British architect Elrond Burrell in a long and thoughtful post. He is using the term Zero-Carbon but I think the terms are, for this discussion, pretty much interchangeable. He gives 9 good reasons why it’s the wrong target, some of which I repeat here:
‘Zero-Carbon Buildings’ are not an efficient use of resources.
‘Zero-Carbon Buildings’; only in the right location?
Again, the issue of constraints imposed by surroundings, like trees, other buildings, limited rooftop area.
But one of the most significant points that he makes relate to what happens when the sun doesn’t shine and the wind doesn’t blow.
‘Zero-Carbon Buildings’ don’t reduce peak demand on the national grid
The answer to this is to not aim for Net Zero Energy, but to aim for Radical Building Efficiency, to build levels of insulation into our homes and buildings so that they don’t create the peaks of demand at times when the renewables aren’t there to meet it.
The dropping cost of solar power is, as Mike notes, a game-changer that will lead to significant reductions in CO2 emissions. But it is no substitute for good urban design that gets us out of our cars, denser housing types that can support walkable communities, and better buildings that use less energy in the first place. As Elrond notes:
