In the twenty years I’ve been upgrading insulation for homeowners all over Atlanta and North GA, I’ve had this question in my mind. What’s the deal? Why is the insulation so measly THIN in our air ducts?
Code restrictions for attic insulation used to be R-19, then bumped to R-30, and now bumped to R-38.
Wall insulation is supposed to be R-13 with an air barrier.
Floor insulation has to be R-19.
But for air ducts in your crawlspace or basement, the code is R-6.
And for air ducts in your attic, the code is R-8.
We Have The Potential
During the summer, what do you think the temperature of the refrigerant is, moving through your AC equipment? If it’s properly charged, it should be in the mid or low 40 degree range.
A typical summertime Atlanta attic, (vented attic) with dark shingles under full sunlight will reach 140 degree temperatures every afternoon. I’ve documented this in 100’s of homes.
For those of you with an HVAC system with air ducts in your vented attic, you know this all-to-well: “Its’ hard to get cold air from a warm pipe!”
Sixth Grade Science
Delta T is the term we use to measure the difference between two temperatures. If the temperature of airflow before an aircoil is 80 degrees, and the temperature of airflow after the aircoil is 60 degrees, the “Delta T” is (80-60) 20 degrees.
Isn’t there some hypocrisy in our code standards? Here’s my thinking:
Life in “Realville”
If I keep my home at 75 degrees, the ceiling of my living space will be 75 degrees. On that hot June afternoon, my attic is 140 degrees. The Delta T for my ceiling is 140-75 = 65 degrees.
My wall temperatures are 75 degrees, and the ambient air outside is 88 degrees, so the Delta T for my walls is 88-75 = 13.
My floors are 75 degrees, and my vented crawlspace is 68 degrees. Therefore the Delta T for my floors is 75-68 = 7 degrees.
My air ducts have 55 degree airflow, and the attic is 140 degrees, so the Delta T is a whopping 85 degrees!
Do you see the issue? Do you see the problem? Isn’t it obvious?
My attic is required to have R-38 insulation for a Delta T of 65.
My walls are required to have R-13 insulation for a Delta T of 13.
My floors are required to be insulated with R-19, for a Delta T of 7.
Here’s the Insult:
But my air ducts, with a Delta T of 85, are only required to be insulated with R-8.
The greater the Delta T, = the higher the R-Value… according to the smart folks who write our official code standards.
Here’s my question for you as a person: Do you live according to the government recommended minimum standards?
- Minimum standards in your diet? (We don’t eat the cheapest diet from the dollar-priced store)
- Minimum standards for your car? (Do you buy the cheapest car with fewer safety features?)
- Do we order the cheapest item on the menu every day? Or buy the cheapest wardrobe, cheapest bed?
If we’re all honest, we like to buy for durability, useability, style, health, and benefits. Once we’re educated on the options, we normally prefer what is best for us and the ones we love (desert notwithstanding!).
I’m Thankful For Codes
Codes are minimum standards, designed to protect the consumer. Without codes, our housing stock in America would be horrific. So, I’m not complaining in this article. I’m merely pointing out a discrepancy. Air ducts insulated to R-8 in a vented attic, or R-6 in a vented crawlspace, is simply the minimum standard… It’s not the best by far! It’s not ideal.
R-8 insulation on a pipe designed to protect the air that conditions our living space, is simply FAIR. It may not be poor, but it is at best, FAIR.
The Dreaded Red Ink
When I was in school, FAIR meant I earned a D on that test. Not so good! In red ink, were the words, “Room for improvement!”
Here’s the bottom line: If your air ducts are in the vented attic, most likely they are not sealed and insulated for optimum performance.
Do you have a $7000 piece of high-tech equipment, moving air through a 20 year old set of air ducts? Is that working well for you? Here’s the red ink, “Room for Improvement!”
Here is our remedy at Bird Family Insulation:
Using closed-cell spray foam insulation, we seal and insulate your entire (accessible) air duct system.
After evaluating and making needed repairs, we spray right over the old insulation. We successfully spray sheetmetal ducts and flex ducts. All of them!
With the highest Delta T numbers in your home, it’s not hard to see the problem. Heck, even your refrigerator/freezer has lower Delta T numbers but has more insulation than your air ducts!
What’s the conspiracy with our air ducts?
For a virtual appointment to discuss upgrading your air ducts, call or email Savannah in our office. We’re happy to help!
Bob Bird, Bird Family Insulation