The following is a guest post by our good friend Miles Dyson of Inspection Connection. Miles is one of Las Cruces, New Mexico’s foremost experts in home inspection, energy rating, and green certification.
All of the heated and cooled air in your home moves through the ductwork. Where is your duct distribution system located? In the attic. Where are summer and winter temperature conditions worse than in the attic?
A study conducted earlier this year on behalf of El Paso Electric examined duct leakage in a set of non-Energy Star rated new homes in the Las Cruces, New Mexico area. On average, the duct systems in this sample set of homes lost 20 to 30 percent of the heated and cooled air flow to the exterior.
My personal experience testing ductwork while conducting energy audits reveals that this issue is far worse in existing homes. Many older duct systems deliver less than half of the conditioned air back to the living space of the home.
Leaky ductwork not only costs dollars and reduces comfort, but it can also lead to health and safety issues. Distribution duct leakage at the attic can lead to negative pressure inside a home and extreme cases may lead to backdrafting of gas-fired appliances – elevating your family’s risk of exposure to carbon monoxide and other harmful combustion gases.
Your attic can be a dirty place with all kinds of contaminants – fiberglass insulation, dust, bugs and rodent and bird feces. Leaks at the ducts allow these particles to move into your home. Most of the dust you wipe up every week was transported inside through your ductwork.
Las Cruces area homebuilders are adopting strategies to mitigate duct leakage problems. Testing of duct systems during construction reveals problems while the ductwork is exposed and can still be sealed by hand.
Energy Star and the new 2009 Residential Energy Code recognize the value of testing during construction and include duct leakage testing as a key measure to improve efficiency.
Another successful strategy brings ductwork into the conditioned envelope of the home.
Air is circulated within the space below the ceiling and not at the harsh ambient temperatures found in unconditioned attics. Ductless systems like radiant floors and baseboard heaters or room-by-room mini split heat pumps don’t require ductwork at all. If you are buying or building a new home, be sure to find out where the ductwork is located and whether the ductwork was tested and sealed.
Leaky ductwork can be sealed in existing homes. A duct leakage test conducted by a certified Home Energy Rater or qualified Heating and Air Conditioning Contractor is a good place to start. If your duct system leakage is found to be significant, a good HVAC contractor or Energy Rater can determine where the leaks are likely occurring and provide solutions to seal the leaks.
The No. 1 place for duct leakage in most homes (new or existing) is at the return air compartment. Generally this is a wood frame assembly located below the furnace and air handler in a hallway or the garage. When you remove the filter (hopefully you are using an air filter) and shine a flashlight into this compartment you see some interesting things.
Likely, you will see 2-by-4 studs with fiberglass insulation installed between them as the barrier at the inside of the return compartment. You will also notice that the insulation is very dirty at the surface – just like a filter when it is ready to be changed. That fiberglass insulation extends up in to the wall cavity behind and beside the furnace and air handler fan. Every time the fan comes on to heat or cool the air inside the home it is also pulling air through the insulation from the walls and the connected spaces from the attic above. This leaky duct space creates a double whammy, loss of conditioned air to outside (or the reverse) and a source of pollutants that get continually circulated into the home.
Solving this problem is simple for most handy homeowners. The interior of the return compartment can be lined with sheetrock, plywood, hard board duct or rigid insulation and the remaining gaps and openings can be sealed with HVAC duct mastic.
A good handyman or heating and cooling technician can do this if you are like me – and not so handy! Don’t ignore your ductwork. If you do, it can cost you dollars, comfort and even your health.
Miles Dyson is the owner of Inspection Connection LC – Professional Home Energy Rating and Home Inspection Services in Mesilla Park and can be reached at 202-2457. Dyson is a RESNET certified Home Energy Rater and ASHI certified Home Inspector.
Contact Picacho Mountain today at 575-523-2500 for more information on building your energy-efficient, green home in Las Cruces, New Mexico. Custom Estate Homes, Patio Homes, Town Homes, and Neighborhood Retail.