Research Project Information

Research Project Summary Information

No Cost Mod 10613-Duct Lining Technology for Sealing/Rehabilitation of Ducts to Improve Energy Efficiency:Thermal Disturbiution System Duct Leakage Feasibilty Study(ST10613)

Steven Winter Associates, Inc.


Among the problems with residential thermal distribution systems, duct leakage is recognized as a monumental problem costing the U.S. over $5 billion, annually. Predominantly, heating, ventilating, and air conditioning (HVAC) equipment and ducts are placed in attics, basements, crawl spaces, garages and other unconditioned spaces. In commercial buildings, ducts are often placed in the uninsulated building zones. Ducts invariably leak to and from outside unconditioned spaces. Because of this leakage, there is not only lost heated or cooled air to the outside on the supply side, but also heating or cooling outside air that leaks into the duct system on the return side. Duct leakage, which results from ineffective sealing, is the most prominent problem found in residential buildings, both existing and new construction.

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Project Description

The Contractor shall identify and select appropriate duct liner materials for evaluation, with particular attention to cost and ease of use. Most applicable duct lining techniques will then be identified and a mock-up prototype duct assembly will be built for test and analysis of the selected duct lining techniques. If favorable results are achieved during the analysis, the sub-contractor (product manufacturer) will be asked to develop a technology licensing agreement for a NYS installation contractor. A demonstration site in NYS will also be identified, and preparations made for the next phase of the feasibility project.


The project reduces energy use by 10% and reduces peak demand by 20%, improves indoor air quality by reducing dust, excess humidity and other indoor pollutant cross-contamination, minimizing temperature variations within occupied space. The equipment used in this prototype project clearly needs to be modified, and adapted for transport ease and use within existing hanging ductwork of 6” or 8” size. The materials have to be optimized also, from pouring resin into a liner, to having a liner set up while being snaked and impregnated within existing smaller ducts. The possibility to seal existing ducts with an impregnated liner, opposed to continuing duct leakage, presents a great energy savings opportunity, along with increased home comfort to desired set points.

Project Results

The Contractor experimented with different resin formulations (suitable for ductwork) that accelerate curing, minimize VOCs, reduce costs, and identified a polyester resin for initial prototypes. Using a video camera setup, with laser profiling system, revealed that profiling circular ductwork is possible and software adjustments will be necessary for profiling rectangular ductwork. The coated liner material was not influenced by protruding metal screws within the interior of the duct. Controlling the amount of resin during the liner impregnation process eliminates the need for “drying” the duct after insertion. Adequate information was gathered from the prototype testing to merit proceeding to the next phase. The Contractor believes that the unique opportunity to develop a new class of ductwork retrofits consisting of snaking/threading deflated “balloons” throughout duct system trunks and branches, under surveillance of video systems, is a possibility. The prototype duct-lining tests reveal that ducts can be sealed effectively, and as a benefit a new, rehabilitated duct within the old duct is formed. Any one duct segment can be lined and cured within 60 minutes, demonstrating that a typical full house duct system can be rehabilitated within one (1) day. The possibility of duct lining only critical joints, and junction points, accounting for most of the leakage measured could be a viable, economical approach. This would minimize labor/materials and promote uptake.


Steven Winter Associates, Inc.
61 Washington St
Norwalk, CT 06854

Principle Investigator

Ravi Gorthala

Universities Involved


Project Type:

Research Study

Technologies Types:

Building Systems

NYSERDA Contact Information

Gregory Pedrick


R&D -Transport & Power Systems

Contract Details

Start Date: 7/28/2008
Project Status: Active
Contract Number: ST10613

Last Updated: 5/7/2012 2