Find more details about these retrofit suggestions at
USGBC Checklist for Green Retrofits:
Switch to compact fluorescent light bulbs
Program your thermostat
Plug air leaks
Tune up your heating and cooling (HVAC) system
Choose ENERGY STARĀ® appliances
Reduce water use
Switch to green power
Explore solar
Use low-VOC products
Plant trees to provide shade and wind protection for your house
Use native plantings