"Energy is consumed by HVAC systems through a number of processes. Air is typically distributed through the ductwork via an electrically‐powered fan. Cooling coils remove heat from the air. Heating coils add heat to the air. Through normal HVAC usage, particulates in the air slowlycollects on the surfaces of various HVAC components, resulting in a gradual loss of energy efficiency. Some loss of efficiency via a single dirty component may be minor. When the loss through each component is added up, however, the impact could be considerable. Generally, the greater the buildup, the greater the energy loss. Removal of the buildup of particulate on HVAC components restores energy performance to the system."
The first step is to clean the lint trap after every load of laundry. By doing this simple cleaning regularly, you will avoid 90% of dryer vent problems. You should perform extensive cleaning annually, or sooner if you suspect a problem. Unplug your dryer and pull it out from the wall, then disconnect the exhaust tube from the dryer and the wall, and clean it with a vacuum.
Air duct cleaning is done by heating, ventilation and air conditioning (HVAC) professionals. The pros use industrial-strength, truck-mounted vacuums and powerful brushes and hoses to clean inside the metal ducts that make up your forced air heating and cooling system. The Environmental Protection Agency recommends duct cleaning if there is “substantial visible mold growth inside hard surface ducts, ducts that are infested with vermin such as rodents or insects, or ducts that are clogged with excessive amounts of dust and debris and/or particles are actually released into the home from your supply registers.”