Step one for saving energy is to install a programmable digital thermostat. In winter, dropping the indoor temperature 1 degree at night and during work hours can cut heating costs up to 3 percent, according to the American Institute of Architects (AIA). Doing the reverse with the a/c in the summer can save 6 percent per degree. And, points out AIA small-projects expert Louis Smith, “You can do it with a screwdriver.“Media Platforms Design Team1. Turn off power to thermostat. Loosen the screw terminals and disconnect the wires, labeling them with masking tape.Media Platforms Design Team2. Mount the new unit through the base of the old one, or use drywall mounts.Media Platforms Design Team3. Connect the low-voltage wires to the correct terminals. (You may need to strip the wires first.)Media Platforms Design Team4. Install the batteries, attach the body, restore power and program the thermostat.