Many home owners use standard 1-inch pleated filters. These filters are excellent for removing particulate matter from the air. However, they are highly restrictive and reduce airflow substantially. A new 1-inch pleated filter can reduce airflow by as much as 20%. This reduction worsens as the filter soils. An effective alternative is to employ the same filter media in a larger format. Rather than a 1-inch thick configuration, we recommend a 4, 5, or 8 inch thick filter. These provide 300–700% more surface surface area than smaller filters, thereby offering extremely low resistance to airflow. Major equipment manufacturers like Trane, Carrier, Lennox offer these types of filters, as do aftermarket manufacturers. However, the initial installation must be completed by a licensed a/c contractor since duct and plenum modifications will be required. Although more costly, these filters last substantially longer than standard 1-inch filters. Use-life of these larger format filters is typically 6 to 12 months.