A more insightful question might be, "How many people can do anything about it?" If you rent, there's not much you can do about your home's efficiency. We've done as much as we can, but we're simply blocked by things out of our control. Here's a good small example: when we moved, all the energy-efficient light bulbs we bought for our old apartment went into a drawer and stayed there. Why? Because they don't fit in any of our new light fixtures, which only take obscure specialty bulbs. Go figure.