Air Filters Put in Garbage Cart/Bin Air Filters Go in the Trash Air filters contain fiberglass, which cannot be recycled. Throw them in the trash. Did You Know? Air Filters Affect Your Home’s Energy Efficiency Leaving clogged air filters in your home can make your heating and air conditioning less efficient. How often they need to be replaced varies with filter quality, furnace use, and the specific needs of your home. A good rule of thumb is to check your filter once a month and change it when it looks dirty. Your air will be cleaner and you’ll save money on your energy bill, too.