After I wrote what the heck is a net zero energy building? not a few people complained that I was getting hung up in the details and missing the big picture. Or as professor and author Tony Denzer noted in a tweet, “Too much worry about the fringe of the garment, in my opinion. (And I enjoy obscure things.)” Others complained that it sounded like I was against the whole idea.
I am, in fact, very much in favor of the concept and believe that every building should be net zero energy, defined by architect and author William Maclay as “producing more energy than it consumes on an annual basis using only renewable energy in the process.” Reading his book, "The New Net Zero," I learned that he shares my view of the fundamental issue with most net zero standards: that they are nit-picky, and that they don’t care about the building and how well it's built, just that they are net zero. Meaning you can have a huge, poorly insulated home but if you throw enough solar panels on the top or buy enough wind power, it can be called net-zero.
These typical definitions for net zero buildings do not put a limit on energy consumption as long as the consumption is matched by renewable production on the property… This means that new or existing buildings that consume high amounts of energy can qualify as net zero just by adding large numbers of renewables on the building site.
Furthermore, the power that is fed back to the house is not necessarily clean green power, so the bigger the system, the more fossil fuels that must be burned to offset it. Maclay reiterates the point that Elrond Burrell made, that we should be first aiming for what he called “radical building efficiency.” Maclay writes:
The first step to a net zero society is load reduction — the reduction of society-wide energy consumption. Instead of focusing singularly on the metric of net zero, we should focus on the energy performance of all new and existing buildings.
A net zero project is one that meets the net zero ready/micro-load energy conservation standard and then adds enough renewable energy production specifically for the project to cover annual building energy consumption. Seems simple, right?
A reasonable compromise? (Photo: The New Net Zero)
Interestingly, Maclay does not go all Passivhaus on us, but looks tries to “optimize energy conservation levels,” looking for a cost-effective balance of insulation, energy performance and renewables. This addresses a common criticism of the passive house/Passivhaus movement: that it costs too much to build to Passivhaus standards and that it doesn’t make sense with the current price of renewables. It's not an unreasonable argument, sometimes known as "the pretty good house."
In fact, Maclay makes totally reasonable points throughout his chapter on defining a new net zero. He concludes:
We have been looking at net zero from a narrow energy input-output model because we believe that energy concerns will be the single greatest challenge to civilizations and living systems in the twenty-first century. However, a more inclusive definition of net zero buildings takes into account that these buildings protect the environment, pay for themselves through improved efficiency, provide stable energy costs, and avoid the need for fossil-fuel-based energy sources.
My only problem with Maclay’s book is that it provides Too Much Information. It’s a big, beautiful and expensive book with a ton of detail on how to build an efficient net-zero building, which the publisher says “is geared toward professionals exploring net-zero design.” However the introduction and the first part, “What is Net Zero?” define a standard for the New Net Zero that should be read by everyone who cares about the subject. It actually makes Net Zero make sense.
Related in MNN and TreeHugger:
- At the NIST Net Zero test facility, the residents are virtual
- ROSE Cottage: A net-zero energy home for all seasons
- New certification finally defines what net zero really means