On March 13th, the Commission for Environmental Cooperation (CEC) issued a report stating “buildings represent the greatest opportunity for considerable reductions in CO2 emissions”.
“Every year, buildings in North America cause more than 2,200 megatons of CO2 to be released into the atmosphere, about 35 percent of the continent’s total CO2 emissions.  In the United States alone, the total built floor space covers over 27 billion square meters, or more than five and a half times the size of Grand Canyon National Park.  According to the United Nations’ Intergovernmental Panel on Climate Change, buildings represent the greatest opportunity for considerable reductions in CO2 emissions, with net economic benefit.”
If buildings are the greatest opportunity to reducing CO2 emissions, then what are the barriers?  The report stated “The barriers to doing improvements to existing buildings is understanding the lifecycle costs of the building.  Understanding the life-cycle costs of a building is still a significant challenge.”  Another barrier is split incentive.  “Often the one paying the bill and the one capturing the benefits differ.  A developer may not be interested in paying for green features when the benefits will be passed on to the new owners or tenants.”
“Green building will help ensure North American competitiveness in the global market for products, technologies, and practices essential to North America’s future. Such products, technologies, and practices include heating and cooling systems, advanced building materials, water-reclamation systems, high efficiency appliances, energy efficient lighting, construction and demolition debris recycling, and many more.”
I would highly recommend that you download the entire report from the CEC.