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.
Ordinary houses breathe through leaky joints and poor seals, losing heat and wasting energy. But our house won't leak, so we'll use a heat recovery ventilator (HRV) to admit fresh air and expel stale air, transferring heat from one stream to the other.