Most homes in the US have
heating and cooling systems that rely on forced air distribution. Most of those
heating and cooling systems are inefficient.If areas in your home are uncomfortably cold in the winter
and/or hot in the summer, no matter what the thermostat setting, it should come
as little surprise. There are various reasons, but a few bullet points would
include:
Oversized equipment
Improperly sized ductwork
Inadequate air flow
Inadequate duct insulation
Excessive air leakage
The National Comfort
Institute (NCI) has conducted research showing the average home's heating and
cooling system performs at only 57% of equipment rated capacity.That's a lot of wasted energy. Can you
imagine your response if you discovered you'd bought a new car that only
performed at 57% of its rated capacity?A duct renovation with testing, sealing, adjusting, and balancing can
increase system performance by an average of 35%.That's a lot of saved energy.
Of the bullet points
listed above, the last, excessive air leakage, has the greatest impact on
indoor air quality.Installed
ductwork across the US has an annual average leakage rate of 30%.As with the previous analogy, can you
imagine if your fuel tank leaked 30% as you drove down the road?You'd be outraged.
This would be bad enough
if it were only a matter of wasted energy.But the system we're discussing should ideally be a closed
loop, with the same volume of air being pulled in for conditioning as is pushed
out and distributed throughout the home.Leaks on either the supply side or return side will create imbalances
that can force unwanted pollutants from wall cavities, crawlspaces, and/or
attics into what you hoped was a safe and healthy environment.Dust, moisture, insulation fibers,
varmint droppings, and all manner of unwanted stuff can find their way in.
As part of our holistic approach, we utilize a Duct Blaster to determine the
amount of duct air leakage in your home's system. A Duct Blaster is a diagnostic tool designed to measure the air tightness of the duct system and to help locate
air leakage sites. It consists of a calibrated fan for measuring airflow rates,
and a pressure-sensing device to measure the air pressure created by the fan
flow. The combination of pressure and fan flow measurements is used to
determine the ducts air tightness. With that essential knowledge, we can
prescribe measures to increase efficiency, and improve Indoor Air Quality.Here are a few examples of problems we commonly find in ductwork installations, as well as solutions to help improve your comfort, health, and safety.
DUCTWORK PROBLEMS IN EXISTING HOMES
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DUCT INSULATION IN EXISTING HOMES
As if duct leakage weren't bad enough, we also find ductwork to have inadequate, torn, or missing insulation. That means conditioned air being moved through the system has to overcome the hot in summer or cold in winter duct through which it's moving. What a waste of energy. Here are a few examples.
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PROPERLY INSTALLED DUCTWORK
At Sustainable Home Solutions we take great care to insure ductwork is properly installed, properly sealed, and properly insulated. To do otherwise is simply a waste of time, money, and energy. Here are a few examples.
Sealing at the Y
When we crawled into this attic we found, among other things, rat feces scattered everywhere. After vacuuming out the old blown-in insulation and debris, the duct insulation looked OK, but when we pulled it back we found evidence of duct leakage. We took the assembly apart, mastic sealed the elbow and connections, then properly insulated it all. You can't see the assembly in the final photograph because we covered it with a nice, cozy, final layer of fresh blown-in cellulose insulation. This proves to be a very successful approach. In fact, we were able to reduce duct leakage from 14% of rated air flow to 10%. Not bad.
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A Duct to Boot Connection:
Here's an example of an old duct to boot connection. We replaced the old duct, mastic sealed the boot and the duct connection, then made sure we insulated the boot itself. We repeated the process at six other locations. This approach greatly improves overall performance of the system.
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Ductwork in a Garage
The dark spots on the insulation in the first photograph are dead giveaways that the duct is leaking. We removed the old insulation, mastic sealed the joints, reinstalled the old insulation, then added an additional layer of FSK insulation.
