How Big Is the Zero Energy Movement?

The Inventory of Zero Energy Homes aims to answer that, and to get more builders on the path to Zero

Thrive Row Houses
Data from the Inventory shows that the vast majority of growth in Zero Energy Homes is in
attached units, like these rowhomes built by Thrive Homebuilders in Denver.

Zero Energy homebuilding has garnered lots of attention from the trade press in recent years. Homes, communities, and builders have been profiled in e-newsletters like this one as well as in print magazines such as Professional Builder. Trade journals have published countless how-to articles on topics like advanced framing, insulating, air sealing, HVAC, and indoor air quality.

No surprise there: cutting edge projects and technologies are always newsworthy and make for good reading. The question is how much actual growth that attention reflects.

Signs from around the industry are encouraging. The International Energy Conservation Code has been gradually lowering acceptable home energy use. The DOE's Zero Energy Ready Home (ZERH) program has certified north of 6500 homes, according to program director Sam Rashkin. Training providers such as EEBA and Construction Instruction report growing attendance at live and online seminars. Last year's EEBA Summit had a record number of attendees. The High-Performance Housing Zone at the International Builder's Show in January was packed to overflowing during the entire three days.

But code adoption and enforcement are uneven, and while those ZERH certified homes provide helpful best-practice models, they're a tiny slice of the homebuilding pie. And despite the popularity of training and conferences, the reality is that pressure to hold down housing costs leads many builders to reject upgrades like better air sealing or high efficiency heat pumps, even though such upgrades can actually lower homeowners' monthly living costs.

In other words, although Zero Energy homebuilding may be on the upswing, its trajectory has not been fully quantified. So inquiring minds want to know: "How many of these things are there, really?"

Team Zero (formerly known as the Net Zero Energy Coalition) set out to answer that question in 2015 with its Inventory of Zero Energy Homes. In the years since, they have documented more than 22,000 projects. They recently partnered with EEBA on the goal of motivating even more builders to get their homes and buildings listed.

San Francisco-based green building consultant Ann Edminster has been leading the Inventory effort since its inception. She was a good pick for the job. With nearly 35 years in the sustainable building field and as a former chair of LEED for Homes, she has an extensive network to draw on. And that's what she has been doing.

"A lot of it is beating the bushes," she says. "Especially at first, when we didn't know who was doing what, we just started bugging people on our contact list. We have since been focused on expanding our network." She admits that getting people to respond has been a slog. "People get so much email that we have to reach out to some of them 10 or 12 times."

Team Zero has also allied with a couple of dozen organizations that have similar missions and has been reaching out to those organizations' lists of builders and architects. The EEBA partnership is the most recent and most significant of those alliances. In fact, EEBA CEO Aaron Smith plans to promote the inventory heavily to their list, which includes more than 55,000 industry professionals committed to high-performance, Zero-Energy building.

"We see the inventory as an extremely valuable resource," says Smith. "EEBA members will be able to submit their projects and compare best practices." He would also like to make the Inventory a more effective learning tool by expanding its scope to include more detail. "I would eventually like to see it updated to include more data on the envelope, solar and mechanical systems people are using."

One thing that's important to note here is that the Inventory casts a wide net. To be included, a project need not be finished but can be under construction or even in the permitting stage. Team Zero's standards for what qualifies are also less stringent than those set by programs like Zero Energy Ready. Some ENERGY STAR homes would probably qualify if their electric needs could be satisfied by a reasonably sized solar array.

"We're not out to pin medals on people's chests. Instead, we want to show what the project pipeline looks like," says Edminster. That's a big part of the Inventory's value: illustrating the industry's progression along what's often called The Path to Zero.

Lessons Learned

How is that progression going? Edminster says that five years of pouring over data and talking with builders has revealed a profitable, growing market. For instance, the 2018 tally included 22,146 units—that's 59% more than the 2017 inventory total of 13,906 units.

What is just as significant as the overall tally are the types of projects it represents. Despite more than 22,000 units, the Inventory only includes 7015 buildings, which means that the numbers skew heavily towards townhomes, rowhouses and apartment buildings. "A full 95% of all projects in the Inventory have two or more units and more than 60% are multifamily projects," says Edminster. "Those numbers show that Zero Energy building has become a serious business."

The picture the data paints is of a building method that's emerging from its embryonic stage and moving into a period of steep growth.

What's also enlightening is where that growth is concentrated. The data shows that most projects are in Zero Energy hotspots spread around the country, most of which have their origin in a single builder.

The typical growth pattern in these hotspots follow what Edminster calls "a virtuous cycle of policy and grassroots action." It usually works like this:

  • One builder decides to start building Zero Energy Homes.
  • That builder's projects receive media coverage, which gets people in the community excited about Zero Energy homes.
  • When other builders see what's going on, they seek out training and get on the Path.
  • These builders eventually team up with consumers to lobby local jurisdictions to create incentives.
  • That leads to incentives at the state level, which drive adoption statewide.

"It's the classic grit in the oyster syndrome," she says. "We've seen it repeated in California, Massachusetts, New York, Colorado and other places." The point is that it only takes one builder to begin moving a market. After all, none of those hotspots had any Zero Energy homes until someone decided to start building them.

Of course, that begs the question of why those first builders got on the path in the first place. Edminster has been talking with high-performance market leaders about this issue since long before starting the Inventory and has heard the same story over and over.

"It's consistent with every pioneering builder," she says. "They simply decide that this is the right way to build, then figure out how to make it work." She also says that none of the high-performance builders she knows has gone back to code-minimum construction and that none have had any problem finding willing buyers.

If you build it, they will come.

Ultimately, Team Zero is hoping that the Inventory will help architects, builders and developers understand that Zero Energy building is a winning proposition. If they succeed in that goal, then more people will decide to get the training they need to become markets leader in new hotspots.

For more information on the Inventory or to submit a project, please to go


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