Center for American Progress:

We are living in an increasingly carbon-constrained world. We need to consider the deployment of every technological and behavioral option to reduce carbon emissions if we are to avert the catastrophic consequences of climate change. Yet we do not necessarily have the luxury of tackling all options at once, particularly given the current global economic crisis. We therefore need to prioritize our low-carbon options on the basis of cost-effectiveness. Energy efficiency represents the most cost-effective, low-carbon strategy compared to other options such as renewable energy, nuclear power, and carbon capture and storage. The cheapest form of energy is, after all, the energy you do not use.The compelling case for energy efficiency is best understood through analogy. It is undisputed in health care that prevention is better, and cheaper, than cure. The same is true in energy and climate. Smartly reducing energy consumption is a more cost-effective approach for reducing emissions than deploying relatively immature technologies such as solar photovoltaics or carbon capture and storage, or CCS, which address the symptoms of a carbon-intensive lifestyle, rather than tackling the root cause of high energy consumption in the first place.

Systems Thinking –