|The U.S. emits the equivalent of 7.26 gigatonnes of CO2 annually.|
|Our buildings contribute 2.49 gigatonnes of that.|
The San Francisco Federal Building, completed in 2007, harvests sun and breezes to replace electric lighting and air conditioning. Stainless steel panels retain accumulated solar heat as a thermal blanket over the building’s facade. When that air warms, it floats upward, coaxing cooler air through the building via windows that open automatically when instructed by sensors. The result is carbon-free air conditioning.
Photo by Tim Haley timhaleyphotography.com
Buildings use a lot of energy, so it’s no surprise they’re responsible for 30–40 percent of CO2 emissions. The challenge involves two tasks—creating new buildings that are carbon neutral, and retrofitting all existing buildings to eliminate their carbon footprint.
The first task is easier. In Germany, Passivhaus homes consume 95 percent less energy for heating and cooling by using super insulation, solar gain, and efficient heat recovery. There are 6,000 homes in Europe built to Passivhaus specifications. Building codes should require that all new houses are built to this standard.
There is no shortage of innovation. In Guangzhou, China, the 69-story high Pearl River Tower will generate more energy than it consumes, using wind turbines inside two floors of the building, solar photovoltaics (PV), and solar heated water. In Målmo, Sweden, the Turning Torso tower, in addition to being powered by local wind and solar energy, recycles organic wastes into biogas that can be used for cooking and to power the city’s buses. In the Chinese city of Rizhao, 99 percent of buildings in the city center use solar hot water. In Spain, all new buildings and renovations are required to get 30-70 percent of their hot water from solar panels.
LEFT: Pearl River Tower in Guangzhou, China will generate more energy than it consumes.
RIGHT: The Turning Torso Tower in Sweden uses local wind and solar energy, and recycles organic wastes into biogas. Photo by Karl Ericsson
The Architecture 2030 initiative is pressing to have all new buildings and major renovations in the United States be 100 percent carbon neutral by 2030—a goal that has been unanimously approved by the U.S. Conference of Mayors.
Britain is moving faster—it is requiring that new buildings all be carbon neutral by 2016. The U.S.-based LEED (Leadership in Energy and Environmental Design) standard for green buildings needs to move in the same direction.
The challenge is much tougher for existing buildings. Most building owners could achieve a 20 to 50 percent reduction in energy use by investing in new windows, super-insulation, heat-recovery systems, and efficient appliances and boilers. Solar PV and solar hot water can be added, and carbon-neutral heat can be obtained from heat exchange with the air, earth, water, and sewage. There are furnaces that burn biofuels, and Sweden’s district heating systems circulate hot water for 50 miles without significant heat loss. Super-insulation, combined with shade trees and white-painted roofs, can also reduce air conditioning load.
To encourage rapid renovation, we need tax credits, self-financing mechanisms, and rules like the Residential Energy Conservation Ordinance, which requires owners in San Francisco and Berkeley to upgrade a building before it’s sold. Germany is paying for a complete retrofit of all older apartment buildings. London has launched a Green Homes Concierge Service to help home-owners upgrade. Since 1993, the small Austrian town of Güssing (population 4,000) has reduced its CO2 emissions by an incredible 93 percent, by switching, among other things, to biofuel district heat for its buildings. It’s just a matter of vision and determination.
|Guy Dauncey wrote this article as part of Stop Global Warming Cold, the Spring 2008 issue of YES! Magazine. Guy is a speaker, organizer, consultant, and author with Patrick Mazza of Stormy Weather: 101 Solutions to Global Climate Change, New Society Publishers.
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