In August of 2010, California legislature passed a bill establishing the most extensive carbon dioxide (CO2) emission controls yet in the United States. The law requires a 25 percent reduction in state CO2 emissions by 2020, with the first major controls taking effect in 2012. This action is the result of the widespread implementation of the LEED standards in the building industry, the largest single generator of Greenhouse Gasses by category. LEED categories and points are structured to account for the embodied energy in building materials and their transport.
What this requires is a means of benchmarking the energy content of materials and their supply chain, which can be a very complex calculation with many different approaches. The industry is beginning to use some standardized digital tools to compare the impact of different materials by computing the energy embodied in the material itself.
For example, concrete has the highest embodied energy of any traditional building material. While concrete itself has an inherently low embodied energy, it must be quarried, produced and transported. Additionally, it is the most widely-used material in existence, thus producing a high net effect of emissions. So widespread is the use of concrete, that nearly 2 tons is produced for every person on the planet. Famously in Italy, its vast use has become a source of toxic waste.
In the US, recycled concrete is becoming a very commonplace material now that codes and regulations are starting to require conservation of energy and resources, such as California has done. It's becoming standard practice to recycle concrete either in place or locally to reduce carbon fuel usage in its transport. The impact that this will have on our building and development practices will be profound. We'll be more like Europe in that buildings will be preserved and salvaged, rather than ripped down every 25 years for a new cheap structure. This affects the design approach for all facilities, which will emphasize long life, low energy and loose fit (flexibility).
This is a sea change in how we value our towns, cities and environments. If we see how buildings and structures actually subtract resources and processes from the ecosystem that sustains us, at the cost of depleting the energy sources we have left, we begin to understand the path we must take in recreating human habitation patterns and begin to change our culture.