If you have a central air system, a lot of its efficiency is determined by how well your ductwork delivers conditioned air to your living areas. Leaky ductwork can lose around 30 percent of your cooling efficiency, and improperly designed ductwork can cost you even more. Following are the things that good duct design takes into account.
Staying Inside Your Thermal Envelope
If your ducts pass through areas of your home that aren’t conditioned, such as attics or exterior crawl spaces, the air passing through can take on the temperature of the outdoor air as it’s passing through the ductwork. That leads to reduced heating and cooling efficiency for you.
Approved Ductwork Materials
In older homes, you may find “ducts” that are simply passages through the wooden infrastructure of your home. These are no substitute for proper metal or fiberglass ducts, which can be balanced properly, cleaned and sealed.
The pressure in your ducts needs to be managed in order to deliver the right amount of airflow to each room, regardless of its distance from your central air system. This balance can be adjusted using manual dampers, though it should be considered thoroughly in the duct design stage.
Return Air Pathways
Your ducts don’t just carry air out to your living areas, they also bring air back from them so it can be re-heated or re-cooled. Each room should have a return air vent or a clear airway path to a return vent in a central location.
Air leaks lose Americans about a third of their heating and cooling efficiency on average. An efficient duct system is a well-sealed and well-insulated one. Ducts should be sealed when they’re installed, and periodically inspected to discover any new leaks.