More than half the world’s population, or 3.5 billion people, live in cities. By 2020 this number is expected to rise to 4.25 billion, and by 2030 to 5 billion. By 2030 a staggering 900 billion square feet of new building space will be constructed in cities worldwide (including the replacement of old buildings), an area equal to three times the total U.S. building stock. We have a choice. How we plan to build and rebuild our communities will determine whether this unprecedented growth will promote sustainability and enhance our quality of life, or accelerate environmental degradation and lead to increased human suffering.
Let’s start with the good news. According to the U.S. Energy Information Administration (EIA), CO2 emissions in the American building sector have flattened and are expected to remain flat over the next decade. The driver of this trend is the dramatically declining demand for energy due to slower growth in construction, increases in building design and energy efficiency, growth in renewable energy production, and “fuel switching” at power plants from burning coal to burning natural gas.
The U.S. building stock is projected to increase 22.6% by 2030. If the best available demand technologies are incorporated in building design, energy consumption is expected to drop 12% and CO2 emissions 21.8% below 2005 levels by 2030. These EIA projections do not include sustainable planning applications or incorporate passive heating and cooling, natural ventilation, daylighting, or spatial configuration and site design strategies. With a growing number of architects and planners employing these strategies to meet the 2030 Challenge targets, we expect actual energy consumption and emissions in the building sector to drop substantially lower.
The problem centers on energy demand. Climate scientists tell us that the way to preserve a planet resembling the one we have known for the past 12,000 years is to phase out the use of coal and unconventional fossil fuels (oil shale, tar sands, and shale gas) that do not capture and sequester CO2. This must be accomplished by 2030.
Cities and urban developments, dense networks of buildings and infrastructure, are responsible for about 70% of all global energy consumption and CO2 emissions. Buildings consume about half (48.7%) of all energy produced in the United States and produce half (46.7%) of all CO2 emissions; globally the percentages are similar. The operation of buildings alone use approximately 76% of all electricity produced at power plants in the country.
Creating livable, healthy, and sustainable cities, reducing fossil fuel energy consumption, and providing access to renewable energy sources are urgent matters of urban planning and building design.