Inexpensive one-inch filters only last one to three months and need frequent changes just to keep your system from being bogged down with dust and debris. Media cartridges or high-efficiency filters are more effective and only need to be changed once or twice a year. The easiest way to remember to change these—and batteries in smoke alarms and carbon monoxide detectors—is to change them all at once during Daylight Savings. Changing your filters as recommended protects your heating and cooling systems, but for noticeably better indoor air quality, ask us about a whole-home air purifier.