Whole House Fan
One of the really nice things about the house when we bought it was that walls were insulated. The houses built in the 60s did not have the walls or floors insulated. The previous owners took the time and expense to punch holes around the house and blow in R-13 grade into the walls.
The first action was to roll out R-19 fiberglass on top of the blown in insulation to bring up the total to R-38. This made a big difference. We are finding that in the evening when everyone is home, that we have to open the front door because the house heats up to 78 degrees just from us running around. We have also notice that the furnace does not turn on as much. PG&E helped pay for half of the cost to insulate the ceiling. This means it cost us $280.
The second action is to insulate the floors. We installed bubble wrap with alinumim foil on both sides under the house. This stuff is rated at R-18 and it made a difference. The first installation we did half the house. Using the morning cold foot test, we could tell where the under the floor insulation stopped. It took a year before we finished installing the underfloor insulation. After doing this, I cannot believe that everyone does not do this. Hardwood floors are known for being warmer than tile, but colder than carpet. Now the hardwood floors are warm to the touch. No need for carpet.
The result of the ceiling, walls and floor insulating project was a gas bill that does not brake $50 a month. Even in the coldest part of January and we have the thermostat set to 75 degrees, the gas bill is barley in the $40s.