When you open a high energy bill, you may become frustrated and cut back on heating and cooling even more. Energy-saving thermostat settings are certainly helpful, and they’re simple to enforce with a programmable thermostat. Thermostat settings aside, how often do you think about ductwork design as being the cause for high heating and cooling bills? Probably not a lot.
The average home loses up to 30 percent of heating and cooling energy expenditures to poor ductwork. So the next time you open a high energy bill or you’re experiencing uneven and uncomfortable temperatures in your Chantilly home, consider giving ductwork design a second look.
Location! Location! Location!
The first thing to consider in ductwork design is location. Many air ducts in the Virginia homes locate the ducts in the basement or crawl space, which is typical. However, even sealed basements are generally much cooler than the heated airflow inside the ducts, which is going to transfer energy dollars out of your pocketbook.
Ducts should be located in the conditioned spaces of the home. Raised floors and sealed chases are good locations. If your ducts are in the attic, consider using insulated metal or flex ducts. These materials keep the air inside the ducts isolated from the harsh temperatures many attics experience.
Tiled drop ceilings are another concealed location that will save energy. If it’s not possible to install ducts in the conditioned space, insulation must be wrapped around ductwork.
Metal or Fiberglass?
Many older homes use building cavities to convey heated and cooled airflow. This doesn’t pass muster in today’s strict home efficiency standards. Moreover, airflow traveling through wall and floor cavities, or between attic joists is susceptible to contamination, such as volatile organic compounds (VOCs), vermin waste, insulation dust and anything else trapped in these locations.
Following are examples of industry-standard ductwork materials:
- Ductwork design should be fabricated of permanent approved materials.
- Sheet metal is the traditional choice; however, many builders are opting for fiberglass flex ducts that allow for smoother turns, and they’re already well-insulated.
- Use appropriate sealing materials that will stand the test of time.
- Sheet metal screws, mastic paste, collars, clamps and metal-backed tape are ideal.
Dampen High Energy Bills
Have you ever closed the damper on an air supply register to control airflow into a room? It’s a common practice to adjust temperature or to block airflow into seldom-used rooms. However, it’s generally not a good idea. Manipulating airflow in this way can create underlying problems, such as unbalanced air pressure and extra work for the blower.
Your HVAC technician should install manual dampers at the trunk and runout, and measure airflow through the home and ducts to adjust accordingly. This also prevents airflow itself from becoming an obstruction by backing up at a closed register. If you really want to save energy and maximize comfort, ask your contractor about an automated zoned comfort system.
Balanced Supply and Return
Balanced air pressure through the ductwork and living spaces is important for comfort and HVAC efficiency. If obstructions exist on the supply side, you get a drop in living space air pressure and comfort. If there aren’t enough return grilles or you don’t check the air filter regularly and it’s often clogged, you get a negative pressure and extreme pressure drop on the return side. This creates excessive work for the blower and often leads to early failure. Additionally, unbalanced pressure exploits leaks in the envelope, which wastes more energy dollars.
Matching a return grille to each supply register is the best method. This isn’t always possible, however, due to space or budget constraints. At a minimum, there should be a return grille on each floor in a strategic location to receive return airflow. Door grilles and jumper ducts may be used to promote airflow room to room, and for rooms with doors often closed.
Sealing and Testing
Even though typical ductwork design has no moving components, ductwork undergoes a substantial amount of stress and static pressure. If the ducts aren’t well sealed, they will fail, so proper duct sealing is vital. The right materials should be used, as recommended by the Air Conditioning Contractors of America (ACCA). The quality and integrity of the sealing job must be tested upon completion and, if required, before insulation is installed.
Learn more about Griffith Energy Services, Inc.’s ductwork design solutions for your McLean home, or contact us at (888) 474-3391 to schedule an appointment!
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