The New York Times has an interesting article on the potential impact (over 10% of US greenhouse gas emissions) of improvements in residential building codes:
"If you build a building well, it’s an asset for 100 years; conversely, if you build a shoddy building, it can be a 100-year liability," said Hal Harvey, chief executive of ClimateWorks, a group seeking to tackle global warming. "Energy building codes are the single biggest opportunity to save the environment while saving the consumer money."
Of course, more stringent codes require more stringent inspections:
Peering behind a bathtub in a newly built house, an inspector, John Umphress, spotted a big gap in the wall insulation. "Somebody took a lunch break!" he complained to the builder, who sheepishly agreed to patch the hole.
With the fix, the house, already a model of energy efficiency, will use even less energy and save its residents money -- for decades.