Date of Award

Winter 2007

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Materials and Infrastructure Systems

First Advisor

Norman Witriol

Abstract

An analysis of residential HVAC ductwork has been performed. Ductwork in 55 homes in Northern Louisiana was tested to determine duct leakage by means of using various measurement techniques to determine the differences between the existing methods as well as the revised method developed in this project referred to as Generalized Subtraction Correction Algorithm (GSCA). A protocol to measure and estimate return leaks at operating pressure was developed. The weighted average return leakage for the homes sampled was determined to be 115 cfm at operating pressure whereas the weighted average duct leakage was determined to be 348 cfm at 25 Pa. A methodology for determining supply leaks at operating pressure based on the input from the return leaks was also derived. Annual energy savings by sealing duct leaks was determined using both REM/Rate™ and a new protocol developed by combining REM/Rate™ and ASHRAE™ 152. These protocols gave substantially different results and the reasons for using the newly developed protocol are presented. Using the combined protocol, the average annual heating and cooling cost per home due to duct leakage was determined to be $347. Homes were also tested for duct leaks in both pressurization and depressurization mode to determine whether the measurements differed. A statistical test on these differences indicates that there are reservations in using these two modes interchangeably. Additionally, the data was statistically analyzed to determine various correlations between various measured and derived parameters.

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