Use caulk around the windows to prevent heat from escaping and cold air from seeping in. Using plastic on the inside traps a thin layer of warm air between the cold glass and the heated room, which helps reduce heat loss. This works more efficiently than plastic, but it also costs more.
Check filters monthly.
They only cost a dollar or two but can result in a more efficient furnace. Have the furnace maintained properly. A professional tune-up can improve performance and save 3 percent to 10 percent on a month s bill. Older furnaces aren t as effective and waste a lot of energy. A new furnace can save up to 30 percent on your heating bill.