[Rain Man]

While not necessarily energy-efficient, our biggest regrets in our kitchen remodel a few years ago are:

1. Not installing that in-floor heating wiring in our kitchen. Maybe it's just the configuration of our house, but the tile floor gets cold in the winter and the in-floor heating would have been pretty cheap.

2. I don't think my wife wanted this, but I missed the opportunity to build an automatic pet water system. Envision a weight pad on the floor in some out of the way corner where, when the pet steps on it, starts a downward-facing water fountain that goes into a little 12"x12" pool with automatic overflow drain. That would've been the coolest thing ever.