Green buildings are an integral part of the solution to the environmental challenges facing the planet. Today we use the equivalent of 1.5 Earths to meet the resource needs of everyday life and absorb the resulting wastes. This measure of our planet’s carrying capacity means that it takes Earth 18 months to regenerate what is used in only 12 months. If current trends continue, estimates suggest, by the year 2030 we will need the equivalent of two planets. Turning resources into (...) waste faster than they can be regenerated puts the planet into ecological overshoot, a clearly unsustainable condition that we all must address. The forces driving this situation are numerous. Human population has increased exponentially in the past 60 years, from about 2.5 billion in 1950 to more than 7 billion todays. Our linear use of resources, treating outputs as waste, is responsible for the toxins that are accumulating in the atmosphere, in water, and on the ground. This pattern of extraction, use, and disposal has hastened depletion of finite supplies of non-renewable energy, water, and materials and is accelerating the pace of our greatest problem—climate change. (shrink)