Seven Things to Know About "Net-Zero"

Seven Things to Know About "Net-Zero"

It's probably not the net-zero you think it is, and it won't do much help with Cambridge's carbon emissions

  • Posted on: 24 September 2013
  • By: stannenb

Proponents of a "net-zero" energy use standard for new construction Cambridge went before the Planning Board and the City Council's Ordinance Committee in August, seeking passage of an amendment to the zoning code that would seek to keep new development from adding to greenhouse gas emissions. Arguing that the world faces a climate crisis, proponents of the Connolly zoning petitition, cite this as the desperate measure called for by crisis. But rather than a desperate measure, when examined, the proposal seems hollow at its core.

  1. The Connollly petition does not implement "net-zero" as it is commonly understood.

    A net-zero building is one that uses stringent conservation methods to limit energy use and, to meet remaining energy needs, generates it on site using wind, solar or geothermal technology. This petition, instead of being "net-zero", allows developers to buy their way out through the purchase of either renewable energy or renewable energy credits.

  2. The Connolly petition neither sets any new benchmark for energy conservation nor provides any real incentive to conserve.

    In 2009, Cambridge adopted a "stretch" energy code to increase building energy efficiency. This petition neither tightens the stretch code nor sets any quantitative benchmarks for energy conservation. The proponents' literature talks about the purchase of energy credits as a "luxury tax" for energy waste. But, to the extent that a building is not truly net-zero, it may purchase renewable energy, which the proponents note is only marginally more expensive than fossil fuels. Thus, it won't cost developers significantly more to have a wasteful building under the Connolly peition than it would now.

  3. The Connolly petition won't reduce Cambridge's carbon footprint.

    Petition proponents note that 80% of Cambridge's carbon emissions come from buildings. Yet this petition won't touch any carbon emissions from existing buildings - the 80% to which the proponents refer - or buildings already under constructions. The best this petition can hope to do is bend the curve and slow the rate at which Cambridge's carbon footprint grows sometime in the indefinite future.

  4. The Connolly petition might even result in an net increasein greenhouse gas emissions for the region.

    The most important large-scale reduction in greenhouse gas emissions come from increased density around mass transit. Every job and every home created in the urban core means reduced automobile use. One of the great nationwide concerns about net-zero is that it promotes sprawl as less dense buildings - short buildings with large floor areas - are typically what results from a net-zero approach. To the extent that net-zero discourages density and that those businesses and residential units are moved out of the urban core, the extra emissions from added automobile traffic might offset any savings net-zero offers Cambridge.

  5. The Connolly petition adopts a building-by-building approach, one that's poorly matched to the reality ofCambridge.

    If Cambridge had large amounts of open space allowing uniform development, expecting a similar energy profile from every building wuld be reasonable. But Cambridge is largely developed, and new construction will occupy idiosyncratic lots. A 2012 study (PDF) by the Alliance to Save Energy calls for a community approach to Net-Zero, noting that mixed use buildings have diverse energy profiles and that common systems, such as a shared heating plant, are immensely valuable for both energy conservation and net-zero.

  6. Written without a public process, the Connolly petition fails to incorporate current best practices in using zoning to control carbon emissions, nor coordination with concurrent Cambridge efforts.

    Cambridge is not the only city looking to control its greenhouse gas emissions. Because there was no public process to develop this petition, there was no means for experts to help provide lessons learned from previous zoning efforts. New York City, for example, has considered "carbon overlay zoning", the building of zoning distrcts designed to provide incentives for reduction of carbon emissions. In Cambridge, the City is working to develop a Kendall Square ecodistrict, another means to create a sustainable community. 

  7. The Connolly petition is better understood as an anti-development petition rather than a sustainability petition.

    Alternately, it can be viewed as a mandate to purchase renewable energy, surrounded by a regulatory regime that is far more complex than needed for this simple requirement. Regardless, it will increase the cost, complexity, and uncertainties of building in Cambridge and inhibit development.

It seems clear that this petition's proponents didn't approach the climate crisis by asking what Cambridge should do but, instead, decided that requiring the elimination of carbon emissions from new buildings through zoning was desireable outcome.

By embracing this approach, proponents have set a goal that is almost certainly doomed to failure. Most net-zero work has focused on more temperate climates where cold winters don't provide a challenge and on larger lot sizes, where significant solar energy can be generated. Proponents have noted singular exceptions pointing, for example, to the Pearl River Tower in Guangzhou City, China as a 71 story office building that meets net-zero standards. There is no doubt that this building is a marvel of engineering, using a range of technologies to reduce energy use and large air intakes to drive wind turbines. But Guangzhou City has mild winters with an average January temperature of 56º and its subtropical location provides abundant solar energy.

The Connolly petition would have had far greater credibility if its proponents had acknowledged two truths. First, the construction of net-zero buildings in a dense urban core with cold winters remains an open research problem. Second, land-use regulation - zoning - is a blunt, controversial instrument in the best of circumstances and its use in building a sustainable community is, as well, an open issue. By not having any community discussions prior to its introduction, proponents leave their motives open to question. At the very least,  proponents should have recognized that the Connolly petition would have been adopted by anti-development forces. It is no surprise that the anti-development Cambridge Residents Alliance, a group that seeks to keep Cambridge safe for automobile traffic, has endorsed the Connolly petition.

Despite flaws, there are many things the Connolly petition gets right. There is a climate crisis and, with the failure of our national government to respond adequately, cities like Cambridge should fill the gap with bold leadership. Energy usage monitoring, given Cambridge's technology-focused innovation economy, would seem to be a natural approach for Cambridge to take. Studies have shown that peer comparison feedback can be more effective than conventional energy conservation messages as a way of reducing consumption.

Meanwhile, residents of our namesake city, Cambridge Kansas, face a state legislature that is considering a bill that would outlaw all state and municipal funding for "sustainable development" which it defines as "development in which resource use aims to meet human needs while preserving the environment so that these needs can be met not only in the present, but also for generations to come." In our Cambridge, we're debating how to be sustainable, not entering into what sounds like a societal suicide pact.

Creative Commons License
Seven Things To Know About "Net-Zero" by Saul Tannenbaum is licensed under a Creative Commons Attribution 3.0 Unported License.

Pictured above is a National Institute of Standards house built last year to test Net-Zero technologies. Photo courtesy NIST

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As one of the more than 400 residents to sign on to the Connolly Petition, I have to admit that I resent the negative tone of this column, which is totally needless and over the top, in my opinion.

To be fair, it's clear that a great deal of effort has gone into this piece...

However, I am afraid that the author has failed to connect the dots. It's as if he is selectively presenting the information to reach his own cynical, "not-in-my-backyard" conclusions about the net zero proposal.

Let's start with Point #1: Yes, "net zero" is commonly used with respect to "zero energy" buildings, but here in Cambridge, with our high-level of urban density, "zero energy" buildings are not practical right now. So instead, we have proposed a standard that makes sense for Cambridge, "net zero emissions." It can be satisfied by choosing off-site renewable energy. Instead of arguing against what this petition isn't, why not just focus on what it is?

Points #2 and #3 completely contradict Point #4. On the one hand, this author, like many of the NIMBYs who oppose the Connolly Petition, claim that it won't do much to limit our emissions. Then, in the very same breath, in Point #4, the author says that the petition will drive development out of Cambridge. Well, which is it? Is this petition going to have an impact, or is it going to kill all development?

The problem with Point #5 is that it once again ignores what is being proposed. The Connolly Petition proposes a "net zero emissions" standard that allows for the purchase of off-site renewable energy at modest prices, but the Alliance to Save Energy study that the author refers to discusses development of zero energy buildings (which is not what we are proposing, see my comments regarding Point #1).

Point #6 completely ignores the fact that the petitioners have been working with the city council and the city manager to create a Task Force that will create exactly the kind of process that the author seems to be calling's unusual for the proponents of a citizens zoning amendment to welcome a city sponsored "task force," but in this case, that is precisely what has happened. We are working together with our partners at city hall, at MIT, in CDD, and with many other stakeholders to ensure that everyone has a seat at the table.

Finally, Point #7 is also off-base. This petition has been endorsed by the Sierra Club, Green Cambridge, the local chapter of, and residents of all different backgrounds and viewpoints, like school committee member Patty Nolan, Central Square businessman Nadeem Mazen, former city councillor Sam Seidel, State Representative Carl Sciortino, the list goes on, and on, and on. I get it: the author has a beef with the CRA, fair enough. But it's unfortunate to say that this petition is anti-development when we, the petitioners, are working hand in hand with all stakeholders to conduct the "net zero" conversation in a positive fashion.