Net-Zero Building Technologies Create Substantial Energy Savings

Net-Zero Building Technologies Create Substantial Energy Savings

Researchers work to package and share step-by-step information for decision making around net-zero energy building technologies.

A photo of 12 people standing around solar panels on a rooftop. Enlarge image

Shanti Pless (right) discusses net-zero energy building methodologies and technologies during a tour of the RSF's rooftop PV system.
Photo by Dennis Schroeder, NREL

The past three decades have seen numerous energy saving innovations in commercial building technologies, including improved insulation, windows, and heating and cooling systems. Despite these strides, energy use by commercial buildings continues to grow faster than the development and deployment of energy efficiency technologies.

By 2030, up to 135 billion square feet of new and rebuilt buildings will be constructed in the United States, representing an increase of approximately 50% in our building floor area. NREL Commercial Buildings researchers are working hard to ensure that this new building space will be highly energy efficient.

"To really have an impact, you have to start thinking about a system of net-zero energy buildings where buildings produce as much energy as they consume," said Paul Torcellini, principal engineer for NREL's Commercial Buildings Research Group.

Path to Net Zero Surprisingly Accessible

To achieve net-zero energy, a building team first reduces energy use as much as possible using low-energy building technologies such as daylighting and high-efficiency heating, ventilation, and air conditioning measures, including natural ventilation and evaporative cooling. Next, to account for planned energy use, the building team focuses on planning for and utilizing sufficient renewable energy sources like photovoltaics, solar hot water, and wind power.

Renewable energy sources located on the building site are preferred, but builders also utilize resources such as biomass, ethanol, or biodiesel that can be imported or purchase off-site renewable energy sources like utility-based wind.

Motivations to realize net-zero energy use can range from federal mandates to environmental and financial considerations. An executive order signed by President Obama in 2009 calls for new federal buildings to be designed to net-zero energy standards by 2020 and operating as net zero by 2030.

Currently only an estimated 1% of commercial buildings are built to net-zero energy criteria. One reason for this small number, according to NREL's researchers, is the diffuse nature of the commercial buildings sector, which makes it difficult for new research to reach and impact the buildings market. As a result, many practitioners in the commercial buildings sector remain unaware of the accessibility of net-zero annual energy design, assuming that it is too expensive.

In reality, NREL's commercial buildings researchers are already utilizing technologies and methodologies that achieve zero energy at little to no additional cost when compared with traditional building methods. NREL's 360,000-square-foot net-zero energy Research Support Facility (RSF) cost $259 per square foot to build, compared with $250-$350 per square foot for a traditional building.

"There's a huge gap between what people think is achievable and what is actually achievable," said Torcellini.

To address this knowledge gap, NREL's researchers are paying close attention to behavioral aspects of the commercial buildings sector, examining the many factors that go into owners' and operators' decision making, from design through operations. Researchers are also working to more effectively communicate information about utilizing net-zero energy building methodologies and technologies. Conveying that net-zero energy buildings are achievable today is a top priority, said Torcellini.

Detailed, Innovative Process Helps Pave Path Forward

One of the processes pioneered by NREL's commercial group and the U.S. Department of Energy (DOE) is energy-performance-based acquisition, which building owners and designers can use to incorporate energy performance goals, language, and incentives into the planning, design, construction, and operation of a building. Recently NREL's researchers worked to incorporate all of their presentations, reports, how-to guides, and other resources into a performance-based acquisition collection featured in DOE's Commercial Buildings Resource Database.

"We're working to condense what we did here at the RSF into something that is accessible to really give people information they can use at the point of decision making," said Jennifer Scheib, an engineer with NREL's Commercial Buildings Research Group.

NREL's collection of resources provides detailed step-by-step information for each part of the performance-based acquisition process, and additional work is underway to develop guidance that will help building owners and operators address and mitigate operational risks. This information will provide needed long-term support for building teams.

"Net-zero energy is an operating goal and not just a day-one goal," said Scheib. "We want to make sure that a building is still operating at net-zero energy in year 20 of that building's life."

The Future of Net Zero

Although net-zero energy is currently being applied mostly to instances of new commercial construction, the concept is likely to take a much broader hold in commercial retrofits as well over the next five years, predicts Shanti Pless, a manager within the Commercial Buildings Research Group. Recently, NREL worked with the General Services Administration to document the lessons learned in attempting to achieve net-zero energy in a retrofit of the Wayne Aspinall Federal Building and U.S. Courthouse, a historic building in Grand Junction, Colorado.

Pless also expects the net-zero energy standard to become a much bigger market differentiator in the near future, with the concept taking hold in schools, banks, office space, and many other areas. He expects to see more voluntary energy codes around net-zero energy and the expansion of the concept to larger scales, such as city campuses.

"Providing information on budget-conscious net-zero energy best practices like NREL is doing is a key part of helping the industry move forward," Pless said.

"Extra cost is often a justification to not be efficient," said Pless. "There are plenty of ways buildings waste energy and money, but good energy efficient design doesn't need to."

NREL continues to pioneer work on controlling plug loads, using energy modeling tools to set energy use budgets, and challenging large building portfolio owners to achieve energy savings within their cost models, among many other areas. With this work and continued efforts focused on communicating information and influencing decision making, the net-zero energy future looks bright, with the paradigm shift NREL's Torcellini seeks on the horizon.

"Consumers should expect nothing less than net-zero energy buildings," said Torcellini. "Consumers should demand excellence out of their design teams and construction contractors."

—Written by Emily Laidlaw

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