Harrison Fraker, professor of architecture and urban design at the University of California at Berkeley, gave an interesting talk on 11/2/11 on sustainable, low-carbon neighborhoods. He profiled four low- to zero-carbon neighborhoods. Two are in Germany, and two are in Sweden. What characterizes all these neighborhoods is that they were designed using a whole-systems approach so that the energy that is used there is also generated there as much as possible; water capture and reuse is also emphasized. He went on to describe how he is applying the lessons learned from studying these sustainable neighborhoods in Europe to the design of sustainable neighborhoods for about 100,000 people and a sustainable campus in Tianjin, China.
Whole-systems thinking for neighborhoods overlaps with the Passive House approach for buildings in that both start with sharply reducing energy demands and both emphasize passive measures—high-performance building envelopes, passive solar design, shading, daylighting—as well as efficient appliances and lighting. The remaining energy needs are intended to be met with renewable sources, including wind, solar, and biogas produced from locally generated green waste, food waste, and sludge.
The two neighborhoods in Germany are the Vauban neighborhood in Freiburg and Kronsberg near Hannover. In the Vauban neighborhood, 42 units meet Passive House standard, with another 50 on the way. All other buildings had to meet a low-energy standard. Vauban is estimated to be one of the largest solar districts in Europe, with almost 5,000 square feet of photovoltaic (PV) panels producing electricity for the residents. A district-owned cogeneration plant meets most of the heating needs for Vauban. An anaerobic digester converts sewage sludge into biogas for cooking. Car-free living is emphasized, with support for public transit and restrictions on parking spaces and very low speed limits in the community. Vauban stands out among these sustainable stars for being the one to best its stated energy performance goal per square footage of housing. Fraker attributes this success to community involvement in Vauban’s design from its earliest stages.
The Kronsberg neighborhood was developed during the 1990s in response to a serious housing shortage. It now houses about 6,600 people in high-density complexes that left room for parks and other open spaces. More than 40 architectural groups were involved in planning the various housing structures, resulting in a variety of design features. Parts of the development consist entirely of homes that meet the Passive House standard. District heating and some electricity are supplied by a cogeneration plant; wind turbines supply additional electricity.
The Malmo neighborhood known as Bo01 is the only one of the four neighborhoods to meet all of its electricity demand through renewable energy sources. Wind and solar power combine to meet the electricity demand, while geothermal heat pumps that use seawater as a heat sink supply heating for the district. Cost-effective solar thermal panels using evacuated tube technology provide hot water. Bo01 includes 3,000 residences with additional office and commercial spaces. Stockholm’s Hammarby neighborhood relies on a district cogenerating system that burns locally produced waste, biogas from sludge for cooking, and heat captured from the wastewater for district heating.
Although redesigning neighborhoods may be out of reach for most communities, there are many lessons on the reuse of locally generated waste that could be applied. As Fraker emphasized at the start of his talk, the carbon problem is accelerating, the impacts on the climate are dire, and we all need to take carbon emissions seriously.
