Net Zero Travelogue
Posted on March 9, 2016
In February, my wife Tamar and I set out on a West Coast tour of super-green buildings and communities, collecting grist for her stint as a guest lecturer on sustainable building design at Tel Aviv University. We saw some wonderful, pathbreaking examples of "net zero energy" buildings and even experienced an instance or two of "net positive energy" structures. Here's a sampling:
Most dramatic in visual appearance and reach is the Bullitt Center in Seattle. Its oversized solar roof last year generated 54% more electricity than the six-floor building consumed -- and that's in often-rainy Seattle, Bullitt Foundation president Denis Hayes enjoys pointing out. He aptly likens the hyper-extended 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 an extraordinary! This impressive result comes from a winning combination of the generous rooftop PV, 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 use and mobility. Though built to be net zero, West Village's actual performance has fallen a bit shy of that goal, and is now about 82% energy self-reliant. Solar photovoltaics on just about every residential roof and parking canopy are key, helped by smart, attractive window shading and great insulation.
Major cause for West Village's 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" supermarket where waste heat captured from long banks of refrigerator and freezer cabinets is used to heat upper-floor apartments in this net zero energy building. Atop this 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 from wastewater - that's right: sewage - to provide about 70% of the Village's heating needs. Here's a great description of how the system works.
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!
These and other meanderings were helpful to Tamar's lecture preps. They also gave me a broader context for thinking about what we can do to trim the carbon footprint of our built environment.