The number of net zero energy buildings in the U.S. has increased significantly over the last decade, and that has changed the perception of these facilities from being an unreachable ideal to a more attainable one.
The New Buildings Institute’s 2016 List of Zero Net Energy Buildings includes 332 facilities that have either verified net zero energy operation or committed to achieving zero energy, a massive increase from the 191 that made its 2015 list. As the industry continues to shift toward sustainable solutions, what kinds of paths are available for you to achieve certification as a zero energy building?
A Zero Energy Tipping Point
First, what's a net zero building, anyway? According to the Department of Energy, net zero means that a building produces just as much renewable energy as it uses. This is usually calculated in 12-month increments, as consumption fluctuates throughout the year with changes in weather. As long as the facility gives as much energy back to the grid as it consumes, it is a zero energy building.
Green building practices have been around for decades, but zero energy buildings have slowly emerged across the country. However, as sustainability and cost-effectiveness continue to overlap, it seems as though zero energy buildings will multiply over the course of the next decade or two.
“I think we are at a tipping point. Right now we have about 65 projects that are certified as having achieved zero energy performance. We have about 400 that are registered as pursuing it through one of our certifications,” says Brad Liljequist, zero energy director at the International Living Future Institute (ILFI). These projects widely vary in use and are categorized as residential, commercial and office, and institutional buildings. Most are new construction projects.
California leads the U.S. in zero energy buildings due to its favorable climate and incentive programs. Portland, OR, and the north Atlantic coast are also leaders in net zero, according to the New Buildings Institute. There are either verified or emerging zero energy buildings in 39 states.
One indication that Liljequist cites as a harbinger for the future proliferation of zero energy facilities is that engineers and architects are not the only people discussing the concept of them. Even those without the expertise in facilities are more frequently coming in with a strong idea of the cost savings and additional benefits that can come with zero energy facilities.
“In the last year, I’m hearing average, mainstream people using the term ‘zero energy,’ which is telling me that we are going to see a very rapid acceleration in zero energy buildings,” says Liljequist. “Within five years, I think we’re going to be talking in terms of tens of thousands of zero energy buildings.”
Certifying Zero Energy Buildings
While there are a number of more general green and energy efficiency building certifications out there, the offerings for prospective net zero energy buildings are less common. Currently, there is one main certification for zero energy; the ILFI has had a program since 2011, and it was revamped in 2017 to create the Zero Energy Certification in partnership with the New Buildings Institute.
The goal of this certification is to provide recognition for facilities that achieve net zero energy usage for 12 consecutive months and to collect information that can be used to inform building owners of zero energy prospects. Over time, this will provide the foundation to perform metadata analysis that will aid their efforts to foster the continued adoption of zero energy buildings.
“We work quite a bit with projects that are in the process of achieving zero energy,” says Liljequist. “We do a lot of coaching, a lot of education through publications and classes, and actual consulting.”
In the update to its certification program, the ILFI looked to simplify the process for certification by reducing costs and documentation, focusing solely on energy performance in facilities and only requiring a third-party review of energy performance to receive certification.
For consideration, buildings need to be “fully occupied.” This doesn’t necessarily mean that the building needs to be filled 100 percent to capacity, but it needs to reach a capacity that represents full functionality for the organization and allow for possible occupant turnover.
The only real criteria for this certification is that the building must generate more energy than it uses over the course of a year. For many buildings that have sought out certification, it can take 6-12 months to get to zero energy performance if it is already close. Those that miss the mark can then reconsider things and find out what is wrong, explains Liljequist.
After receiving certification, there are no other required checks or audits, which theoretically means buildings could operate at net-zero levels and receive certification before dropping off in efficiency. However, if you prepare well enough and incorporate appropriate systems and materials in your building, you are likely to maintain and even improve performance over time. Strong preparation and following through with the best energy efficiency practices are key to ensuring optimal performance, and getting occupants involved with these practices helps significantly.
“Having some kind of metering that is public and helps keep people aware of how performance is going is vital,” says Liljequist.
The idea of zero energy buildings might conjure images of the most advanced technologies and building systems or, for FMs, high costs. A lot of the systems and improvements that are necessary to make your facility net zero are expensive, but they offer high ROI when the right changes are made.
However, the costs associated with zero energy buildings are decreasing over time. One of the main reasons going zero energy costs less than it has in the past is because high quality, efficient building materials and systems are easier to find, more abundant in the marketplace and ultimately less expensive.
“There’s no cutting edge technology in our building. We just corralled the already existing energy-saving technologies in one place,” says Craig Neyman, vice president and CFO of the David and Lucile Packard Foundation, about the organization’s headquarters located in Los Altos, CA.
The Packard Foundation’s headquarters has consistently performed as a net zero facility, and it has paid off. Neyman notes that while the decision to go net zero was in large part motivated by the Foundation’s mission of conservation, the investment was defensible because of the building’s strong ROI.
If you are thinking about zero energy for your organization, you will want to consider your location. Some regions are more conducive to net zero energy based on climate – for example, sunny and more temperate areas will perform better with solar and place less of a demand on HVAC systems. Nevertheless, zero energy buildings can be put into use in any number of climates; it might just require more effort in buildings that weather harsher conditions.
Just as some organizations have found the cost of making a facility net zero energy, they have found that maintenance is typically simpler and a rarer occurrence than before.
“They tend to be more durable, simpler and easier to maintain,” explains Liljequist. “Often, the envelopes of the buildings are built better, so in the long haul you’re going to have less maintenance and less potential for rot if it’s a wood frame structure. Windows are often higher quality, so they’ll be durable. A lot of living buildings are using ground source heat pumps and heat recovery ventilators, and all that equipment is inside the building instead of being on the roof where it would be exposed to weather and is tougher to maintain.”
Steve Stenton, director of sustainability at RMW architecture & interiors, likens the durability and reduced need for maintenance in zero energy buildings to that of electric vs. gas cars, where electric cars have fewer moving parts and are therefore easier to maintain than a gas-fueled car. Likewise, because mechanical systems in zero energy buildings are typically smaller than that of a comparable conventional building, this generally equates to simplified maintenance.
“It’s based on the old adage ‘less is more.’ There are fewer things to go wrong with it and therefore generally fewer maintenance issues,” says Stenton.
Justin Feit firstname.lastname@example.org is a former Associate Editor of BUILDINGS. This article was originally published in 2017 and updated in 2018.
Systems That Contribute Most to Zero Energy Buildings
As zero energy buildings become more common, consensus is building about the most effective systems to contribute the best performance. Brad Liljequist, zero energy director at the International Living Future Institute, highlights the following four systems as having the greatest impact:
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Envelope: Liljequist starts with the building envelope, which can in many cases be the easiest to retrofit in a building. The key is making sure your building is properly air sealed, and most facilities that have successfully met zero energy goals have paid attention to the air barrier and are doing performance testing. Common envelope improvements include double and continuous insulation and high performance windows.
Heat Pump: Because of the amount of innovation that has happened in the last 10 years, the right heat pump can be a great technology to make your building more energy-efficient.
Plug Loads: “People are really paying attention to occupant loads using individual submetering to understand how individuals are using power in the building,” says Liljequist. The switch to LEDs and more widespread adoption of daylighting also contributes positively.
Solar PV: On the energy generation side, solar PV is typically the best way to produce power in your facility. In some cases, on-site wind energy can be a means to fulfill your facility’s generation needs.