hornflips

What are some improvements you'd recommend for improving the efficiency of existing houses? I'm talking "best bang for your buck" kind of improvements.

I realize this depends on the age of the house and the quality of the build, so it may be better to ask what the biggest variables in efficiency would be in an existing house.

What internal processes do you use to keep things so reliable (ITIL, etc.)? Essentially, what is Service Management like at Google?