A recent report by the World Business Council for Sustainable Development shows that contractors, in general, overestimate the cost of building energy efficient homes. That means that they're less likely to persuade clients that building 'green' is worth the investment.
But there is much more information in the report. Data about the amount of building space per capita in various countries and trends on increasing energy demands are fascinating and startling. Take a look. Then share your opinions in the comments section.