Build a home energy-management system that (1) controls the temperature in every room based on its occupancy and a local thermostate in every room, (2) extinguishes the lights, other appliances, and suppresses heating wherever there aren't any people, (3) learns the habit patterns of the occupants of the home and adjusts accordingly, and (4) can easily be retrofitted to an existing home without surgery.

It must independently manage the heating outlets in every room. It must independently manage the lighting and other controlled energy sinks in every room. It must be readily installable at $50 per hour for a combined labor and materials cost of $40 per room, plus the control unit.

That will make you rich and keep you busy for quite some time.

RE