Editor’s note: This article first appeared in the July/August 2016 issue of Business Energy.
Buildings account for nearly 40% of the nation’s energy use. Why does this matter? Because it means that while buildings are a big part of our energy challenge, they also have the potential to be a major part of the solution to a clean energy future. That’s why the US Department of Energy (DOE) has made energy efficiency a major priority in its mission to advance cost-effective and innovative efficiency solutions and technologies to achieve substantial energy savings. It’s a smart strategy that also supports economic development, job growth, and the improved competitiveness of American businesses.
One of the ways the DOE is working to advance energy efficiency is by focusing efforts on Zero Energy Buildings (ZEB). ZEBs rely on marrying deep, cost-effective energy conservation strategies with onsite renewable generation. Achieving a zero energy project is a major accomplishment, but it can be very challenging.
The market is responding. Project teams throughout the country are looking seriously at setting goals to achieve zero energy. In fact, the number of ZEBs doubled from 2012 to 2014. Today, roughly 160 projects have reached zero energy and another 53 projects are looking to meet this ambitious milestone. However, as more projects aspire to meet this goal, the market has run into two important barriers. First, market leaders still suffer from a lack of clarity around what actually defines a ZEB. Second, project teams are eager to find resources to help them navigate the technical path to zero energy.
As for the first barrier, the market is filled with various, often inconsistent definitions from multiple organizations. The ensuing market confusion about the end goal can hinder the already difficult task of designing, constructing, and operating an energy efficient building. In order to alleviate this market barrier, the DOE partnered with the National Institute of Building Sciences (NIBS) to work with a large, diverse group of industry stakeholders in order to develop a common definition for a ZEB. The resulting A Common Definition of Zero Energy Buildings report released by DOE establishes that a ZEB is, “an energy efficient building where, on a source-energy basis, the actual delivered energy is less than, or equal to, the onsite renewable exported energy.”
“NIBS and the Department of Energy have created a set of clear and concise definitions for zero energy buildings that will help to narrow the broad array of terminology currently used in the industry and will contribute to the growth of zero energy building construction across this country,” says Ralph DiNola, CEO of the New Buildings Institute.
The establishment of this definition addresses aspects such as measurement of source versus site energy, and how to treat unconventional energy uses like a plug-in vehicle, allowing building owners and project teams to best focus their efforts on implementing the appropriate strategies to improve the performance of their buildings. Successful deployment in both the commercial and residential sectors has facilitated the transition of DOE’s focus to the educational sector with a particular focus on K–12 schools.
Schools serve as an integral part of any community with high visibility, a variety of functions, and a powerful mission. While the quality of educators and course curriculums are arguably the most important factors that contribute to the student body’s performance, it is also imperative to address the quality of the built environment they learn in.
Recent research conducted by Harvard University’s T.H. Chan School of Public Health’s Center for Health and the Global Environment, SUNY Upstate Medical University, and Syracuse University has shown that improved indoor environmental quality conditions result in drastically improved occupant cognitive ability. The education sector accounts for approximately $14 billion in building construction and renovation, and has grown consecutively for four years. This provides abundant opportunities to incorporate zero energy design, operations, and maintenance strategies in schools. Thus, DOE is poised to release a technical guidance document in early 2017 consisting of strategies to assist engineers, architects, and school stakeholders in incorporating zero energy design strategies, while addressing aspects like energy consumption, renewable energy, and operations and maintenance.
Discovery Elementary School, located near the nation’s capital in Arlington, VA, is an example of a school designed to be zero energy. The result of a collaborative community-based design process, Discovery is the first new project as a part of a 10-year, Capital Improvements Program intended to set a new standard for sustainability and efficiency, as well as for the design of learning environments for the county of Arlington.
With the ability to host 650 students, the approximately 98,000-square-foot building was designed to meet an Energy Use Index (EUI) of 23 kilo-British-thermal-units (kBTU) per square-foot a year, which is substantially less than the regional average consumption rate of about 70 kBTU per square-foot a year. The school boasts many energy efficient technologies and operations strategies to meet its ambitious EUI goal, including 1,706 mounted solar panels, a geothermal well field, pre-heated domestic water via solar tech, 100% LED lighting, ideal solar orientation and shading, high thermal mass exterior walls, and bio-retention areas that clean and release all water from the site.
Discovery’s design team utilized “massing” in order to meet the essential number of photovoltaic panels required to achieve zero energy operation by breaking down the two-story building into smaller components. The PV system’s implementation cost was about $1.5 million and will have an estimated return on initial investment of about seven years, with an annualized return of 6.3% over 20 years.
Coupled with the additional energy conservation savings, the school’s operating costs are estimated to be $47,000 less than those of an average Arlington County Public school in its first full year of operation.
Oftentimes, project teams are not cognizant of the importance of the multi-faceted approach required to take a zero energy project from conception to actualization. Discovery’s interdisciplinary team, comprised of traditional architects, mechanical and lighting engineers, zero energy engineers, cost estimate experts, civil and structural engineers, landscape architects, and consultants, was imperative to the successful completion of the project.
Taking things a step further is the state of Kentucky where the Kentucky Department for Energy Development and Independence and the Kentucky Department of Education are working tirelessly to continuously increase the number of high-performance schools in the state. Kentucky currently has 324 ENERGY STAR schools, ranking 10th for the highest number, and 2nd per capita among the 50 states. The creation of a healthy and productive environment that is cost-effective to operate and maintain, reduces energy consumption resulting in revenue saved by school districts, and incorporates sustainable features that transform the facility into a three-dimensional classroom is not difficult according to Lee Colten, Assistant Director of the Division of Efficiency and Conservation. However, it does require an integrated, whole-building design approach, and standard setting.
Richardsville Elementary School, located in Warren County, KY, is a 72,285-square-foot facility housing over 500 students, and thanks to zero energy design, its energy consumption is 75% less than the average school in the US. Constructed at a cost equal to that of a conventional school, Richardsville produces as much energy as it consumes through a 349-kW solar panel array. The school’s energy and environmental goals are also integrated into learning goals for students by involving them in the monitoring of the building’s performance. Energy teams composed of students analyze the school’s plug-in devices and lighting, students monitor its recycling program, and the weather station—a component of an outdoor classroom—helps the students monitor solar panel efficiency.
The Kentucky Department of Education has also identified zero energy ready schools as a means to achieve its energy efficiency goals. According to the Department, a zero energy ready school is one that is designed with components and building strategies incorporated into the design process to achieve state-of-the-art energy efficiency. These buildings target operation at or below 25 kBTU per square-foot a year and are constructed with hardware and engineering in place to readily accept renewable energy installations at a later date. Currently, there are 14 zero energy ready school projects in Kentucky that have been initiated or completed, one of which is Turkey Foot Middle School, located in the Kenton County School District.
Turkey Foot was built in 2010, with an impressive square footage of 133,000. Hardware to support the installation of solar panels at a later date was included in the initial construction. Prior to the application of its solar array, Turkey Foot’s energy consumption was at an EUI of 25 kBTU per square-foot a year. After the 443-kW solar panel array was installed in April of 2012, the facility’s energy consumption fell to 13 kBTU per square-foot a year, as shown by data collected over a year (May 2012 through April 2013).
The resounding message from project teams involved in zero energy design and construction is that, while there are hurdles to successful completion, these challenges are not insurmountable. It is imperative to start with an integrated design process that engages all stakeholders in the design, construction, and operational aspects and allows for the establishment of expectations of each individual, as well as a thorough understanding of what project goals are. Additionally, the design phase should commence with high efficiency in mind and incorporate strategies like a high-performance building envelope, active day lighting, geothermal HVAC systems, monitoring controls, dedicated outdoor air systems with energy recovery and carbon dioxide sensors, infrastructure for renewable energy sources, and operations and maintenance plans.
Too often funding of operating budgets is a difficult challenge for school boards to meet. Building a school to be zero energy allows the money saved through the aforementioned energy conservation techniques and application of renewable energy sources to be returned to the school system’s operating budget facilitating an increase in resources available for instructing.
While the DOE understands that market transformation takes time and the implementation of zero energy buildings industry-wide will certainly not happen overnight, its aim is to spur greater market uptake of such projects by supporting project teams through zero energy technical and guidance-related resources. Champions like the Arlington County School Board and the Kentucky Department of Education, which have both set ambitious high-performance building goals, are also working to encourage the transition to healthy learning environment, helping zero energy buildings become much more commonplace in the sector.