From high-rises to subdivisions, the U.S. is getting closer to building sustainable and resilient zero-net energy communities.
Doing more with less — it’s an axiom the public sector has heard for years. Usually such a call to action is based on rising demand and limited budget. But it also describes what is achievable when communities take committed action to reduce energy consumption. Serious efforts to reduce energy use is leading to the ultimate doing-more-with-less goal — achieving zero-net energy (ZNE) communities. This vision encompasses homes and commercial buildings that use on-site systems and renewable sources to generate at least as much energy as they consume.
ZNE development has so far been expressed primarily in individual projects — a single residential development here, a single commercial building there. Now, cities are looking at how to extend ZNE goals from individual sites to large-scale developments and even entire communities.
At the same time, the nation’s soft energy infrastructure is undergoing change as government regulations are accelerating the move to ZNE development. For example, the California Public Utilities Commission set a goal for all new residential construction to be ZNE by 2020 and all new commercial buildings by 2030. Additionally, all new federal bui
Although there has long been discussion about energy conservation in the built environment, the actual number of ZNE buildings is still small. The New Buildings Institute identified 160 North American projects (individual buildings or districts) that have either achieved or are targeting ZNE as of 2014.
With so much attention paid to energy conservation over the years, why is this number so low? One reason is that the construction and design industry, as well as municipalities, have yet to fully determine how to specify and work with new materials, equipment, processes and techniques.
In El Dorado Hills, Calif., a suburb east of Sacramento, another seemingly typical subdivision is sprawling across once-pristine foothills. But within the otherwise ordinary housing tract is a particularly special house known as the ZeroHouse.
The 2,600 square-foot ZeroHouse has three bedrooms, two bathrooms and a list price of $535,000 — about 8 percent more than neighboring homes. But the ZeroHouse, built by homebuilder KB Homes, features an advanced greywater recycling system, a rooftop solar system with lithium-ion battery storage, triple-pane windows and an attic that is completely sealed with heavy-duty insulation. These, among numerous other innovations, brings the ZeroHouse close to ZNE status.
The ZeroHouse is one of several such homes builders are offering. Another ZeroHouse was recently built in Lancaster, Calif., a city that is aiming to become the “Alternative Energy Capital of the World.”
“KB Home’s groundbreaking efforts to incorporate the latest water- and energy-saving technology into homes have been simply astounding,” said Lancaster Mayor R. Rex Parris earlier this year following the unveiling of a ZeroHouse there. “These are exactly the type of partners we need in our journey to become the nation’s first net-zero city.”
APUS worked closely with local officials and community members while developing its building plans. “For any local government, I would encourage them to be open to change and new types of building design and construction,” said Michael White, vice president of tax, budgeting and facilities management at APUS. “But organizations will have a more positive reception if they are sensitive to the local area and design buildings with compatible architecture.”
Local governments and developers can take advantage of federal funding programs for energy conservation to cover some project costs. Additionally, “State environmental departments can provide guidance as a company goes through all the regulations and permitting processes to construct a green building,” said Mike Gunia, APUS associate vice president of facilities.
Parallel to the changes being made by the design and building industry, city planning departments have identified relevant revisions to building codes and compliance monitoring. These changes are necessary to encourage use and appropriate application of ZNE technologies and designs in new construction and renovations.
New approaches to these issues may also be appropriate, as shown by the city of Seattle. To help commercial buildings achieve ZNE status, Seattle’s energy code defines an optional target performance pathway.
“Target performance allows developers to design a building that doesn’t fully follow the specific techniques defined in the code,” said Duane Jonlin, energy code and energy conservation advisor for the Seattle Department of Planning and Development. “Instead, if they can prove the building meets the required performance levels of real-world energy use data, they can use alternative technologies or methods that are more suitable for the project.”
With local codes in mind, architects have energy-use targets and design tools that help identify effective options for building layouts, systems, features and specifications. However, the construction planning stage commonly modifies the building design, especially to make necessary trade-offs among materials, features, construction methods and costs. Once constructed, energy efficiency is impacted by what occupants do, such as using power-hungry equipment or leaving lights and computers on all night.
“The question for code enforcement becomes: Who do you make responsible for compliance, the designer or the occupant?” said Zachary Hart, director of policy at the American Institute of Architects. “This issue of how to apportion compliance correctly is significant, yet there’s currently no consensus between government and business about the right way to do it.”
The wider availability and declining costs of renewable energy technology is encouraging interest in ZNE construction for both new builds and remodels. For example, residential solar is viable in all U.S. climate zones, especially when solar is integrated as a new home is built versus a retrofit.
However, homeowners often take a short-term view of the potential payback for residential renewable energy systems, which limits their adoption. Dr. Fred Beach, assistant director for policy studies in the Energy Institute at the University of Texas at Austin, noted electricity has been so abundant, cheap and readily available for so long that people don’t understand the paradigm of having self-generation energy systems in their homes.
“Homeowners are concerned because some of these systems may need 10 years or more before they deliver a payback,” he said. “And because people may not be in their homes that long, they are also concerned about the impact of these systems on resale value.”
Yet unlike many home renovations, energy-generation systems can produce a payback and ongoing income if the homeowner sells excess power back to the local electric utility.
“Energy-generating systems for homes allow residents to go from passive consumers of energy to active participants in the energy marketplace and be fairly compensated for the energy they provide,” said Matt Sloustcher, a spokesman for automaker Honda, which is now developing home energy management systems — with a showcase ZNE home on the University of California, Davis campus.
Dr. Beach noted that many developers are incorporating renewable energy technology because the financial benefit is increasingly clear. At the community level, many U. S. cities are participating in the 2030 Challenge, an educational effort that brings together businesses, government and residents to create entire districts of energy-conscious buildings and shared resources for energy generation.
Attracting investment in leading-edge projects such as ZNE can sometimes prove problematic for the public sector. Terry D. Bennett, senior industry program manager, civil engineering and planning at Autodesk, said the key to funding might be using technology to visualize, simulate, analyze and ultimately showcase how low or net-zero energy community projects work before any shovels are in the ground.
“If we can show what the design is intended to do, what the lifecycle costs are going to be, how much it’s going to cost to operate — if private sector can see the transparency, if they understand the value and can see how’s it’s going to work, I think it will attract investors.”
Developer and citizen education can also be part of the cycle for major code revisions discussed previously. “Seattle has a very inclusive process for defining code revisions, with lots of public comment sessions and email discussions,” said Jonlin. “Although this is a long process, it turns out better ideas and helps all of the participants in the building industry jointly figure out how to address new requirements, such as those for energy efficiency.”
Dr. Beach recommends looking to Japan for ideas on encouraging community-scale initiatives for energy efficiency and residential self-generation deployments. Because Japan is dependent upon external fossil fuel supplies to meet 95 percent of its needs, energy costs are very high. This factor has led the country to strongly support residential use of alternative technologies, especially solar and urban fuel-cell installations that use natural gas or biogas.
Best practices for ZNE development will emerge as U.S. cities continue to consider the impact of energy consumption on economic and quality-of-life issues. An ongoing dialogue among local governments, citizens, businesses, technology and utility companies, and the building industry will create momentum for bringing entire communities to zero energy use. The future structure of cities is, at least in part, one in which less is more.
Editor's note: This feature originally appeared in the November 2014 print edition of FutureStructure. You can download the issue here.