TreeHugger has long had a “just what we needed department” for devices that nobody ever needed. We are pleased to announce that it is expanding its portfolio into Labels and certifications with the word Zero in them. Because here comes yet another, from the people we admire at Architecture2030 and the Rocky Mountain Institute. It’s called Zero Net Carbon, or ZNC. It’s defined as:
..a highly energy efficient building that produces on-site, or procures, enough carbon- free renewable energy to meet building operations energy consumption annually.
Now I must explain that I have long been skeptical of the concept of Net Zero. Usually achieved through the use of solar, I have noted that it disproportionately favors those who have rooftops, preferably big ones on one-story houses on big suburban lots. It is biased toward low density with and low rise in a time when we have to be promoting the opposite.It’s why I have always preferred Radical Building Efficiency over Net Zero: it helps everyone in any kind of building, and doesn’t rely on gizmo green stuff on the roof. That’s what Architecture 2030 was all about too, but everybody is on the Zero bandwagon and I guess they felt left out. And they are addressing some of the issues I have raised, trying to address all building types:
A zero net carbon (ZNC) building definition must accommodate all building types – new and existing residential, commercial, institutional, and industrial buildings – in various settings, including those located in dense urban environments where on-site renewable energy production may be limited.
They also say that they are Efficiency First, an important feature.
While the metrics for a “highly energy efficient building” should be defined by each jurisdiction and professional organization, a ZNC building dramatically reduces its fossil fuel generated energy consumption, first through building design strategies and energy efficiency measures, then incorporates on-site renewable energy systems and then procures locally produced renewable energy to meet the balance of its energy needs.
And then they allow for the use of fossil fuels with their concept of Net Balance:
A zero net carbon balance is achieved when an equivalent unit of carbon-free renewable energy is produced (on or off-site) to offset each unit of fossil fuel energy used by the building. The “net” balance of carbon-free energy is critical to the definition, as this provides a path to achieve ZNC for buildings that use some form of fossil fuel energy or are unable to produce sufficient renewable energy on-site.
So if I have got this right, I can (1) build an office building of some level of unspecified efficiency, (2) put as many solar panels on the roof as will fit, (3) burn fossil fuels for the balance, as long as I (4) offset it by purchasing from a green power source. We actually were very critical of an office complex in Ja Jolla for pretty much doing exactly that, and it was Net Zero Energy Building Class 4.
The 2030 challenge was straightforward: “All new buildings, developments, and major renovations shall be carbon-neutral by 2030”…These targets may be accomplished by implementing innovative sustainable design strategies, generating on-site renewable power and/or purchasing (20% maximum) renewable energy.” It had a target and set limits on offsite renewable purchases.
Net Zero is not so straightforward. A skinny tall building with lots of people in it is going to have a harder time than a short building with lots of roof and fewer people. A short building next to a tall building that gets shaded. A building in a cloudy city vs one in a sunny city. On-site Net Zero simply doesn’t scale, doesn’t do urban, ignores that we are part of a larger society and that sometimes things are better done collectively. (Cue the anti-commie comments)
Zero Net Carbon tries to address these problems by making up the difference between what can be done on site and what cannot. But it doesn't really scale either; there is only so much landfill gas you can buy to offset fossil fuel natural gas, and there are lots of questions about whether doing so is meaningful or verifiable. It's much the same story with green electricity; it is not something that is baked into the building, and can be changed at any time by the owners.
Zero Net Carbon puts a new label on what a lot of people have been trying to do with Passive House or Architecture 2030: Design to use as little energy as possible, and make up the difference with renewables. But there are so many Zero standards now that the term is almost becoming meaningless, like sustainable and green. Does Zero Net Carbon tell us anything new or different? Does it add value? Will it stand out in a crowd? I am not so sure.
But I will add it to this endless list of other Net Zero standards, collated by the ASBEC where it will totally get lost: