This is something slightly off the beaten path in terms of my blogging. I was pointed to this article in lowtechmagazine.com (link at bottom).
Barcelona makes use of some rather interesting zoning regulations that encourage a passive solar climate that uses street angles and height restrictions to ensure that everyone has access to daylight, but that all streets also have access to shade. All this comes with a density of 100 units per acre. Paris by contrast is 120 units per acre. So you can get really good densities and less energy dependent housing providing you make intelligent use of your natural environment.