Carbon Neutral and Net Zero

The Case for Net Zero Energy Buildings

LOTT Headquarters Renderings
courtesy of Miller Hull Partnership.

A multitude of reasons exist for designing more energy efficient buildings, from the complex and unpredictable social and economic impact of global warming to the simple and straightforward reality of rising energy prices. Quite simply, however, the writing is on the wall: our quality of life, today and in the future depends on using energy more efficiently.

Buildings account for about 40 percent of total U.S. energy use and are responsible for about 50 percent of CO2 emissions. Those of us involved in the design, construction and operation of buildings have an opportunity and a responsibility to work toward maximum levels of energy efficiency, thereby, significantly reducing CO2 emissions.

What is a Net Zero Energy Building (NZEB)?

A NZEB is a building that, on an annual basis, produces as much energy as it uses. This means that at certain times of the year it may produce more energy than it needs, while at other times it produces less. The balance is traded back and forth between the building and utility company in the form of electricity. It's also possible to go beyond net zero and design buildings that produce more energy than they use each year.

What is Carbon Neutral and How Does it Relate to NZEB's?

A building that is Carbon Neutral uses no fossil fuels in its operation, creates no direct greenhouse gases, and, as a result, does not contribute to global warming. The energy it uses may be produced on site or may be drawn from a utility grid but it must be "clean," produced by wind turbines, photovoltaics, or other renewable energy system. Thus, a building that is both Carbon Neutral and Net Zero Energy produces at least as much renewable energy as it uses each year.

Leadership is Mobilizing

Momentum is building quickly within our industry to meet the challenge of Net Zero Carbon Neutral buildings. Among the organizations that have established pertinent strategic plans and programs are:

  • Architecture 2030 Challengeg. Started in 2002, this non-profit's 2030 Challenge sets a timeline for reducing fossil fuel consumption to zero (i.e. Carbon Neutral) by the year 2030, starting from a 60 percent reduction in 2010, with 10 percent additional reductions every 5 years. The 2030 Challenge has been embraced by organizations including the U.S. Conference of Mayors.
  • US Department of Energy (DOE).DOE's Building Technologies Program calls for commercially marketable NZEB's by 2025, and focuses on better integration of existing technologies as well as development of new ones. Its Lawrence Berkeley National Lab is investing $100 million in technology research and development to help achieve the 2025 goal. 
  • US Green Building Council(USGBC). It's hard to find anyone in our industry who has not heard of the USGBC's LEED program, a now common measurement standard for green buildings. The local "Cascadia" chapter of the USGBC has raised the bar even higher with its "Living Building Challenge," which sets forth 16 prerequisites that all buildings must meet, including net zero energy. 
  • ASHRAE. This organization of mechanical engineers has rolled out the "ASHRAE Vision 2020" program, focused on developing the "the tools necessary to design, construct, and operate NZEB's" so that they are market-viable by 2030. ASHRAE aims to have the necessary tools in place by 2020 and has already completed its Advanced Energy Guides for small office buildings, small retail buildings, K-12 schools, and small warehouses. In the works are user-friendly energy modeling interfaces, target energy budgets for building types and climates, and, by working with manufacturers and others, equipment with greatly reduced plug loads.

 PSU Engineering Building. 
Rendering courtesy of ZGF Architects

The path to a Net Zero Energy Building (NZEB)

Designing and constructing a NZEB requires commitment,special expertise, and collaboration in an integrated design process, from all members of the project team including the building owner or developer, architect, engineers, contractor, and even the building occupants.  The path to net zero can be summarized as follows:

  • Establishing clear, aggressive energy goals and communicating them to all members of the project team is a crucial first step. Unlike the process of traditional projects, all decisions affecting a NZEB need to be made in the context of their impact on energy usage.  This is a way of thinking that requires a commitment to educate and a willingness to learn on the part of all team members.
  • Understand the Climate. Traditional designs have focused on maintaining comfort in climatic extremes such as the hottest summers and coldest winters while frequently paying little attention to opportunities for savings when conditions lie between those extremes. More sophisticated controls, better equipment turndown options, and other readily-available technologies and techniques allow buildings to be in better sync with local climate conditions and energy demands throughout the year.
  • Reduce Energy Loads and Use. Detailed knowledge of how energy will be used in the building will inform choices about where to save energy. Architectural factors such as building orientation, massing and geometry, percentage glazing, insulating values for walls, roof and glass, and daylighting obviously have a huge impact on overall building energy use. The energy efficiencies of equipment used by building occupants also need to be optimized - from computers and copy machines to refrigerators and microwaves-with automatic controls to reduce or eliminate energy consumption when equipment is not in use.  Efficient HVAC systems that use no fossil fuels and lighting systems that rely more on daylighting need to be designed in an integrated fashion with the architectural systems.  (New Directions in HVAC for a brief listing of such systems)
  • Utilize Natural Energy Resources. In different areas of Oregon, for example, we see many types of natural energy available at the building site: solar (for heat and/or electricity), wind, wave, biofuels, geothermal and hydroelectric. Green power is also available for purchase from most local utilities. Harvesting these natural energy resources may be the area where the most opportunities exist, and the most progress will be made in the coming years. They are approaching cost effectiveness, especially with assistance from government and utility rebate and incentive programs.

How Close are We?

Our region's building industry is recognized nationally for its tremendous strides in the pursuit of buildings that are carbon neutral and net zero energy. While there are not yet any completed net zero buildings in the region, a few examples from Washington and Oregon, of buildings that are representative of these efforts are:

  • The Columbian Headquarters. This LEED Gold certified office building in Vancouver, Washington uses 50 percent less energy than code, and with substantial help from its open loop geothermal heating and cooling system, is very nearly carbon neutral.
  • LOTT Wastewater Alliance Headquarters. Located near Washington's state capitol complex in Olympia, this building will use 40 percent less energy than code and draw much of the energy it does use from a methane-fired, combined heat and power (CHP) plant. The methane will come from LOTT's nearby wastewater treatment plant, where it is a waste byproduct.
  • Tillamook Forest Center. Tucked in the forest near the Oregon coast, this interpretive center uses 30 percent less energy than code and is heating by boilers that use wood pellets produced from local forest waste products. It approaches carbon neutrality.
  • Morken Center for Learning and Technology at Pacific Lutheran University (PLU). This building on PLU's campus in Tacoma, Washington uses 45 percent less energy than code, with help from natural daylighting, high efficiency artificial lighting, and a closed loop geothermal heating and cooling system. It is the first carbon neutral building at PLU, which aims to become a completely carbon neutral campus by 2020.
  • Port of Portland Headquarters/Airport Parking Structure (HQP2). Pursuing LEED Platinum certification, projected to use 50 percent less energy than code, this under-construction project features natural daylighting, high efficiency lighting, and a closed loop geothermal heating and cooling system. With help from green utility power, this building will be carbon neutral.
  • Sokol Blosser Winery Barrel Storage Facility. Among the earliest LEED-rated projects, this facility in Oregon's Willamette Valley uses earth berming to reduce heating and cooling loads and draws all its energy from a photovoltaic (solar-electric) system. This makes it a carbon neutral Net Zero Energy building
  • Shizen Condominiums. This small condominium complex planned in Portland is projected to use 60 percent less energy than code because of its high performance envelope, photovoltaic system, and biofuel combined heat and power (CHP) system. It is aimed at net zero energy use.

PLU Morken Center.
Photos by Ekert & Ekert Photography.
Courtesy of ZGF Architects

The technology and knowledge base to design and construct Carbon Neutral and Net Zero Energy Buildings exists today, and the momentum to do so is growing rapidly. For those of us involved in the pursuit of sustainable buildings, it is an exciting time.

In the years to come we'll stand together to meet the challenge of designing cost effective buildings that use no net energy and have no negative impacts on the environment around them. We'll do it because it has to be done, and because we are the only ones who can do it.

Additional Resources

  • Another excellent article on the topic, "The Zero Effect" can be found in Engineering News Record, June 16, 2008.
  • A number of carbon calculators are available through the Web. EPA has developed several. One calculator that adjusts for specific regional power supply mix is EPA's PowerProfiler.

Written by Paul Schwer, P.E. LEED AP, President of PAE Consulting Engineers, Inc., a leader in sustainably focused mechanical and electrical engineering services and based in Portland, OR. He was named Engineer of the Year in 2004 by BetterBricks, the commercial buildings initiative of the Northwest Energy Efficiency Alliance, for his commitment to sustainable, high performance buildings. That same year, the Sustainable Industries Journal named him one of the top 25 Green Building Leaders in the Northwest. He is featured in the new nationally-aired documentary "A Passion for Sustainability."

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