California Energy Commission

Consumer Energy Center
Summertime Energy-Saving Tips:
”Replace air conditioner filters: Dirty filters restrict airflow and can cause the system to run longer, increasing energy use. Replace filters monthly for maximum benefit. (Save: 1-2 percent)”
http://www.consumerenergycenter.org/tips/summer.html

Winter Time Energy-Saving Tips
Five Action Steps to Cut Natural Gas and Propane Use:
” . . . Replace or clean furnace filters once a month. Dirty filters restrict airflow and increase energy use. Now is also the time for a furnace "tune-up." Keeping your furnace clean, lubricated and properly adjusted will reduce energy use, saving up to 5 percent of heating costs.”
http://www.consumerenergycenter.org/tips/winter.html