Net Zero Energy Travelogue
March 14, 2016
Since Beacon’s publication of Harness the Sun last Fall, I’ve spent a lot of time in university classrooms and on radio shows talking up solar power’s potential as a clean energy resource. These discussions have largely focused on the supply side of renewable energy, but there’s a broader and equally exciting story to tell about the rapid transformation of our built environment. It’s a story that is as much about what we can do to reduce our buildings’ energy demand as it is about what we can do to produce the power we need to comfortably use those buildings.
A West Coast tour of super-green buildings and communities in February opened my eyes to many of the possibilities in this quickly evolving realm. I was the tag-along on a trip that my wife Tamar, an architect at Studio G Architects here in Boston, arranged to gather grist for her stint as a guest lecturer on sustainable building design at Tel Aviv University.
We saw some wonderful, path-breaking examples of “net zero energy” buildings and even experienced an instance or two of “net positive energy” buildings. Most dramatic in visual appearance and reach is the Bullitt Center in Seattle. Its oversized solar roof last year generated fifty-four percent more electricity than the six-floor building consumed—and that’s in often-rainy Seattle, Bullitt Foundation president Denis Hayes enjoyed telling us. He aptly likens the hyper-extended wafer of a roof to a graduating student's headgear, the mortar board.
Altogether, the Bullitt Center has an Energy Use Intensity, or EUI, of 11, outpacing its projected EUI of 16. Translating this from new-energy-speak into more familiar terms, the EUI is calculated by dividing a building’s total energy use (measured in thousands of Btu) by its overall floor area. Without going into further detail, trust me: an EUI of 11 is extraordinary! This impressive result comes from a winning combination of the generous rooftop photovoltaics, super insulation, automatic louvers for shading, computer-controlled windows that actually open, and ground-source heating and cooling. Oh yes, and tenants who truly care about the building’s energy performance.
On a neighborhood scale, we were particularly taken with the West Village at the University of California’s Davis campus. This new community on the edge of the UC Davis campus hosts hundreds of student apartments, clustered around a central public square with a cafe/restaurant, grocery store, and a few research institutes that focus on energy and mobility issues. Though built to be net zero, West Village’s actual performance has fallen a bit short of that goal; the community as a whole is now about 82% energy self-reliant. Solar photovoltaics on just about every roof are key, helped by smart, attractive window shading and great insulation. A major cause of the shortfall in achieving net zero energy is the user population: the designers based their energy use calculations on multi-family occupancy. As it turns out, students sharing these apartments—each with their own collection of electronic gadgets—are bigger energy users than the typical nuclear family. Another mistake was installing washer-dryers in every unit, making it too easy for students to run multiple loads and invite friends from other dorm complexes to drop by and do their laundry.
In Vancouver’s Olympic Village, we visited an “Urban Fare Express” supermarket where waste heat from long banks of refrigerator and freezer cabinets is captured and reused to heat upper-floor apartments in this net zero energy building. Atop the building and on rooftops throughout the Olympic Village, we spotted neat arrays of solar thermal collectors. Supplementing what the buildings themselves generate, a Neighbourhood Energy Utility extracts heat drawn from wastewater—that’s right: sewage—to provide about seventy percent of the Village’s heating needs.
And what about environmental equity in this super-pricey community? Twenty percent of the Olympic Village’s residential units qualify as “social (affordable) housing,” and eleven percent are rental apartments.
Another project we visited—Tassafaronga Village in Oakland, CA—has made affordability one of its central features. Located in the southeastern part of the city where occasional blocks of low-income homes crouch beneath highway overpasses and industrial warehouses, this neighborhood complex combines green roofscapes with solar PV and solar water heating, earning it LEED Neighborhood Development Certified Gold Plan status.
Helping us pull all these strands together was a Net Positive Energy + Water Conference in San Diego, organized by the International Living Future Institute (ILFI). When in Seattle, we were happy to visit ILFI’s headquarters on the ground floor of the Bullitt Center. Talk about mission-appropriate office space!
The National Renewable Energy Laboratory estimates that we can get a fifth of total U.S. power needs by tapping the sun that falls on our rooftops. If we pair up all that solar power with new buildings designed to meet unprecedented standards of efficiency and performance, eventually we just might be able to neutralize the carbon footprint of America’s built environment.
About the Author
Philip Warburg, former president of the Conservation Law Foundation, is the author of Harness the Sun and Harvest the Wind—both published by Beacon Press. Follow him on Twitter at @pwarburg and visit his website.