Save Energy — Air Distribution

Centralized heating and cooling equipment is more efficient and allows locating in an out of the way place. Conduits called ducts are used to distribute the hot or cool air throughout your home. The effectiveness of this system called ductwork plays a critical part in your comfort and utility bill. If there is any one source of unknown energy waste it is the ductwork.

Your Home Energy Living Plan

  • Do not block supply registers and return grilles.
  • Examine ductwork for leaks and repair.
  • Add insulation around ductwork if it runs in an unconditioned space like the attic or crawl space.
  • Obtain the services of a heating/cooling contractor to analyze and balance your ductwork.
Impact of Your Energy Saving Actions

Nearly half of your annual utility bill goes to heating and cooling. Ductwork can account for 20% to even 40% losses of this energy. Improvement can have a major impact. However, the best savings occur from hiring a contractor to analyze, repair, and balance your ductwork.

How Energy is Lost

A major problem is the air leaking out of the duct. If this air leaks out in an area that is not conditioned like the attic or crawl space, then this is a major energy waste. The attic and crawl space are considered outside; both spaces are vented with outside air. Some people consider leaks inside your home unimportant. This is not true. Air should come out the supply registers and return through the return grilles. This allows adjusting for the optimum airflow to each room. Leaking air is uncontrolled and unplanned. Leaking air will most often reduce the amount of air to rooms at the end of the system. These rooms will be uncomfortable resulting in the tendency to change the thermostat to compensate. This wastes energy.

For the system to work, air must return to the central unit. The way air returns is as important as supply. To reduce construction costs, the return path may be a wall cavity or other opening in the wall, ceiling, or floor. These spaces tend not to be air tight and can pull air from anywhere. Even when the return is ducted, leakage pulls unwanted air into the heating/cooling unit.

Improperly sized ductwork can also waste energy. There is a tendency to reduce the size of ductwork to reduce cost and better fit into spaces. This reduces airflow to some rooms resulting in comfort problems. In severe cases airflow is reduced to your entire home. To evaluate the effectiveness of your ductwork requires a contractor with experience in this area. Ask for certifications specifically for air distribution.

Energy Solutions Explained

Blocking registers and grilles interrupt the proper flow of conditioned air. This results in discomfort. The usual action to counter this is to adjust the thermostat. This in turn results in over heating or overcooling some areas. You may accept a higher temperature in your living room so that the far bedroom is not too cold. This increases energy use.

In areas you see the ductwork, you can place your hand near the joints in the ductwork to check for leakage. In some cases the duct may have broken away or have been damaged by later construction. If you have floor registers or grilles, remove them and look down inside (you may need a flashlight). It is easy for floor opening to collect all kinds of potential obstructions.

You can repair small leakage with tape rated for ductwork (do not use duct tape). You can reattach any flexible duct that has pulled away from its connection. Large leaks or broken or damaged ductwork should be repaired by a contractor. Insulation can be wrapped around any ductwork that runs through the attic and crawl space.

The heating and cooling is a system. In other words that means adjusting a register in one room can affect another room. Closing several registers can impact all rooms by lowering the airflow of the central fan. Assessing the ductwork for proper size is best left to the professional. A professional will be able to identify parts of the ductwork that unnecessarily increase resistance to airflow. For example, some duct transitions can create more resistance than a small diameter straight run. Some heating/cooling contractors only install equipment and do not have the necessary expertise to evaluate your ductwork. Carefully select a contractor who has experience in air distribution. Have contractor explain and show you all problem areas.

Special note here is that studies have shown duct cleaning has little or no energy savings. Very little accumulation of dust or dirt occurs in the ductwork. However cleaning may be necessary after any construction. Construction dust and debris seams to always collect in the ductwork.

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