Zero net energy is the building industry standard for energy-saving design for any building that produces more energy than it consumes, thus reducing energy needs from traditional non-renewable sources and reducing carbon-based air pollution. After years of confusing or conflicting definitions, the U.S. Department of Energy in 2016 defined Zero Energy Buildings (ZEB) as: “An energy-efficient building where, on a source energy basis, the actual annual delivered energy is less than or equal to the on-site renewable exported energy.” (1)

In ensuing years, the definition has expanded to include many different buildings and groups of buildings and complex metrics for evaluating any project.

Usually a ZEB entails photovoltaic (PV) solar panels and/or wind generators along with battery storage. But this can be achieved only through energy conserving measures that go way beyond building and energy codes to reduce power demand for the building’s normal operation, such as:

  • Thermally efficient building envelopes, including high-performance fenestration carefully designed to reduce solar heat gain and provide optimal interior daylighting
  • Geothermal “wells” or arrays that provide year-round sources of heat or cooling energy
  • LED light fixtures and very energy efficient electrical appliances, HVAC, and hot water systems
  • Passive solar systems or techniques

This includes connections to a commercial grid to enable selling excess power back to the utility. Thus, the electrical operation of the building balances out to net zero operating cost for power. Over time, the initial cost can ideally be recouped so the whole energy system can “pay for itself.” 

Initially, this concept was never intended to utilize carbon offsets to compensate for a building owner – corporate, business, institutional, manufacturer or residential – who was unwilling or unable to pursue this path to high energy efficiency. It wasn’t meant for those who wanted to appear to be doing the right thing for the environment but were not actually committed to reducing greenhouse gas/carbon emissions. 

There are, however, many excellent examples of corporations, institutions, and residences that have achieved a true net zero energy rating. Some early examples include:

Other notable examples include the Net Zero Energy Center (San Leandro, CA), a world-class learning environment for electrical apprentices; Discovery Elementary School (Arlington, VA) the largest zero energy school in the U.S. in 2016; Center for Sustainable Landscapes, Phipps Conservatory and Botanical Gardens (Pittsburg, PA), the first facility in the world to meet four highest green building standards; Georgia Tech’s Kendeda Building for Innovative Sustainable Design, the first Living Building Challenge building in the Southeast (3); and Net Zero Energy Residential Test Facility (Gaithersburg, MD), an ongoing demonstration project “to achieve net zero energy for a newly constructed house with conventional architecture, amenities, and size compared to homes in the surrounding area.” (4) Click the names to see these buildings.

Net zero energy for residences is a microcosm of what it takes to make a commercial building net zero. 

With this in mind, along with years of studying the basics of sustainable design and the intricacies of the highest green building standards, I have developed several goals for the long-delayed renovation of our (wife, Mary) mid-century ranch/bungalow. One of these goals is to make it as close to net zero energy ready as possible. “Ready” means all the energy conserving measures are in place, ready for the PV solar array. These will include: 

  • Maximizing roof insulation to R35 with spray foam insulation and may include some board insulation as well
  • Optimizing exterior wall insulation as close to R30+ as possible, with modern membranes to minimize air and water infiltration 
  • Replacing a relatively efficient gas furnace with a heat pump system (all electric) with heat recovery/exchanger and fresh air ventilation
  • Replacing our relatively new, very efficient gas water heater with a highly efficient electric water heating system
  • Utilizing Earthcraft by Southface protocols to minimize air infiltration
  • Incorporate a partial new roof structure and finish to add a PV solar array and battery system when it is more affordable with net metering and (hopefully) tax breaks
  • Replacing all old windows with new, very high solar heat gain reduction, low-e/UV protection windows (not PVC or standard fiberglass)
  • Utilizing LED lighting 100% throughout (already 95% there)

It is a huge challenge, but we hope to complete it within the next two to three years.

References:

  1. “Defining Zero Energy Buildings,” High Performing Buildings, ASHRAE, Winter 2016
  2. Ibid: all examples preceding
  3. “Detail: Kendeda Building High-Performance Wall”, Architect, February 2020
  4. High Performing Buildings, ASHRAE; various issues

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What expertise could you share to help our congregation learn about sustainability? Could you summarize some of the research you’ve done in preparation for a house or gardening project? The Climate Action Team would love to hear from you! Please email Jon Reese at reeseindecatur@gmail.com.

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