Is Duct Leakage Stealing Your Energy Dollars?

Unless you have already had your ducts properly sealed the answer is more than likely yes. Studies have shown that the majority of ducts are leaky, even in new homes. C.L.I. Group, LLC can help to reduce this considerable energy loss by performing a thorough evaluation of your duct system. This evaluation measures and quantifies your duct leakage using what is known as a "duct blaster" or by using "Delta-Q" duct leakage evaluation. These are the two most accurate means of quantifying duct leakage. Once the leakage is quantified, we can determine if the duct system is a good candidate for sealing. If sealing is called for, we will seal the ducts and test the pressures as the job proceeds using pressure pans to assure that major leak sealing is successful. Finally, after completing the duct sealing project, we will run a full test on the system to compare with the pre-sealing tests. This allows us to verify that the intended results have been achieved.

Duct leakage to the outside has the largest impact on HVAC system performance. Duct leakage to the outside commonly results from leaky ductwork running through unconditioned zones (attics, crawlspaces or garages). Most of the duct leakage research studies referenced have been performed on houses which contain significant portions of the duct system in unconditioned zones. However, significant leakage to the outside can also occur when all ductwork is located within the building envelope. In these cases, leaky ducts passing through wall or floor cavities (or the cavities themselves may be used as supply or return ducts) create a pressure differential between the cavity containing the ductwork and other building cavities indirectly connected to the outside. Air can be forced through these leaks whenever the air handler fan is operating.

A 1991 study in Florida found:
• Air conditioner use was decreased by an average of 17.2% in a sample of 46 houses where comprehensive duct leakage diagnostics and sealing were performed.
• These houses saved an average of $110 per year on cooling bills at a cost of approximately $200 for repairs.

A 1991 study in Arkansas found:
• Duct leaks also waste energy in heating climates. A study of 18 houses showed that a duct leakage repair service saved 21.8% on heating bills by eliminating three-quarters of the duct leakage in the study houses.

Commercial Duct Leakage

Source: LAWRENCE BERKELEY NATIONAL LABORATORY REPORT NO. LBNL-53356

The EPA estimates that nationally, duct leakage costs the average homeowner 20% of his/her heating and cooling bill. Leaky ducts in the attic or in the crawl space contribute to indoor air quality problems by pulling in dust, including insulation dust and pollens, radon, out gassing of chemical soil treatments, and possibly carbon monoxide and fumes from paint or other chemicals stored in an attached garage. Because leakage to the outside brings in dust, cleaning ducts without sealing them is a waste of your money.

For further information on studies and HVAC installation concerns go to our HVAC page.

Air Conditioning Contractors Association

In order for home owners to be comfortable a duct system must be designed to carry the right amount of air, at the right speed, into the right room. If the ducts are the wrong size then the wrong amount of air will enter the room and may cause:

• The room to be too warm or too cool
• The air to be too drafty and disturb people while they sleep, eat, read, etc...
• The air to be too noisy and drown out conversations, TV or radio programs, etc...
• The air to be too slow – the conditioned air will not circulate or mix well in the room.
• The fan to work harder, possibly fail sooner, and use more energy to move air
• The furnace or air conditioner safety devices to stop equipment operation
• Pressure differentials that may increase energy costs by pushing out conditioned air or drawing in   unwantedair

Duct Leakage Facts:

Major leaks at panned return in basement of new construction. Basement was depressurizing.	Major leakage at return in basement. Poorly installed returns using floor cavities.	Supply leakage at supply run off of main trunk. This adds to elevated energy costs.	Leakage at plenum.
Poorly installed panned floor returns. Contribute significantly to basement depressurization.	Excessive use of flex duct, poor support, hard bends, etc. act to diminish airflow and efficiency of system.	Duct leakage in attic leads to large ice dams on building, potentially causing further damage, leaks, mold, etc.	This drop ceiling return plenum was pulling moisture, combustion contaminants and unconditioned air into commercial building.

Building Sealing

Leakage in the building envelope is critical to any energy retrofitting project. Without properly sealing hidden areas of leakage in the building envelope, retrofits such as added insulation may not achieve the intended results. Many homeowners look into their attics and see deep, blown insulation in their attic and cannot understand why their homes are uncomfortable and energy bills are high. Air Leakage is the answer. Air leakage through the insulation reduces R values and leads to convective heat losses. This leakage is overlooked during construction because builders feel that some leakage in a building is needed for ventilation. This is not true. Indeed, ventilation is necessary. However, controlled ventilation is what works best. It is this hidden air leakage that needs to be addressed in order to achieve a comfortable and energy efficient environment. In addition to energy considerations, this hidden building leakage can contribute to other problems such as structural degradation, moisture problems, mold and soil gases penetrating into the building envelope.

Sealing the building envelope requires qualified technicians in most cases. Much of the leakage in the envelope is hidden and requires specialized equipment for detection (blower door, thermal imaging (infrared) devices, duct blaster, etc.). In addition, building tightening must be monitored to assure that proper ventilation, combustion air and building pressures are monitored for potential problematic or dangerous conditions which must be accounted for as part of the overall building tightening process.  

C.L.I. Group, LLC assures safe and reliable results by measuring and monitoring progress throughout the process of building and duct sealing. This allows for the intended results to be achieved without compromising the integrity of the building systems or safety. Sealing the building envelope and the duct system properly is the most cost effective retrofit available to homeowners. Now this service is made available to Greater Cleveland homeowners.

Infrared reveal some interesting truths about new construction:

Thermal anomalies indicate major air leakage at top plate of interior wall.	Extensive air leakage in building envelope = oversized systems, high energy costs, ice dams	Recessed "canned lighting" in new construction. Energy code requirement for airtight, IC rated obviously not followed.	Large areas of leakage in a brand new home. This home was experiencing large ice dam problem.	Wall cavities (leakage pathways) in new construction. Home was experiencing condensation problems.

Company Policy

It is our policy that independent third parties should measure performance, not installation contractors. We perform duct and building sealing because of the lack of qualified contractors that perform such services and because companies performing such services must have the available training and equipment to perform testing throughout the project. By having our employees perform the sealing, we can measure performance throughout the sealing process. This assures RESULTS!! You will be provided with detailed measurements from before and after which verify the results which have been achieved.

C.L.I. Sealing Procedures

Our 44 point Advanced Sealing  Program covers all of the bases on buildings being constructed. This is always the best way to seal a building, during the construction phase. If you are having an existing home sealed, we will create a prioritized list for the sealing project, dealing first with the largest leaks. Some areas may be inaccessible in existing homes and the decision on whether or not to create access to seal these areas will be evaluated after sealing all accessible areas and measuring results. In most cases, a considerable reduction in air leakage is possible with limited destructive procedures. We will then re-measure the home using advanced blower door, duct blaster and infrared technology to verify the results of the sealing process. By performing diagnostic testing before, after and during our sealing procedures, we can evaluate the successfulness of the project and provide documented evidence of the results. This form of measuring results as the project proceeds allows to also determine when their is a reduction in cost effectiveness of further sealing. 

By properly sealing the building, the insulation, when installed will perform as intended. In many of the building we evaluate, there is insulation present, it is simply not performing due to leakage in the building envelope which creates wind washing and convective heat losses.

Some of the information below discusses the problems of insulation being confused as an air barrier. The fact is, most insulations are not impermeable to air infiltration or exfiltration. If air is permitted to continue leaking, the insulation loses it's effectiveness through reduced R value and convective heat loss.

In all cases, we offer what most contractors do not. Measurable RESULTS!!

Further Information:

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