If you don't know what "passive solar" means, immediately read this post explaining it. If you have a short attention span, feel free to skip the first few paragraphs.
Occupant behavior can make the difference between an efficient house and a wasteful one. Notorious energy hogs include plasma TVs, old refrigerators or freezers, ice-makers, and dehumidifiers. And don't overlook sneaky items like DVRs, always-on computer and entertainment equipment, etc.
A premium home needs a fancy gas range, right? Wrong! An electric induction burner has the same power and quick response as a gas flame, but it uses energy more efficiently and won't demand (cold) makeup air as it gobbles up oxygen. And chefs love them!
Before installing solar panels, get a home energy audit to find out where you're wasting the most energy. Your house will be more comfortable if you seal leaks and add more insulation, so don't just slap solar panels on the roof without curbing energy use.