With the constantly rising cost of energy, we all try to save energy in any way we can. Since heating and cooling make up about 50% of our energy bills. The United States Department of Energy reports that changing your HVAC filter can improve the efficiency of your HVAC equipment by 5% to 15%. Imagine that savings in dollars: Say your average utility bills total $200 a month – that could mean a savings of $10-$30 a month and up to $360 a year! Most people will change their filters at the start of a new season, when they know the equipment is going to be working its hardest. Some people, on the other hand, change it once a month – just to be on the safe side. What are the factors that determine how often the air filter should be changed? Keeping all the above factors in mind, your filters should basically be changed when they are dirty. While this may seem like generic advice, it all depends on the living condition in your home, the type of filters used, and how often and how hard your HVAC equipment is used.