Measuring residential duct efficiency with the short-term coheat test methodology

Paul W. Francisco, Jeffrey Siegel, Larry Palmiter, Bob Davis

Research output: Contribution to journalArticlepeer-review


Assessing the thermal efficiency of a forced-air distribution system is difficult, in large part because of interactions between energy loss mechanisms and other building characteristics. This paper describes short-term coheating, a method of measuring the thermal efficiency of residential heating and cooling distribution systems in situ, and presents the results of a series of studies that utilized the short-term coheat methodology. Short-term coheat tests were conducted in 53 residential buildings including both site-built and manufactured housing. The magnitude of the distribution efficiency, defined as the ratio of the energy required to heat the building if there were no duct losses to the actual heating energy required, ranged from less than 50% for homes with disconnected ducts to more than 90% for well sealed and insulated systems. Duct retrofits were also performed at 20 of the test sites and, following the retrofits, on average, the homes required 16-17% less heating energy. These results show that residential distribution system losses can be responsible for substantial energy loss and that duct retrofits are a viable energy conservation strategy for homes with distribution systems located outside of the conditioned space.

Original languageEnglish (US)
Pages (from-to)1076-1083
Number of pages8
JournalEnergy and Buildings
Issue number9
StatePublished - Sep 2006


  • Duct air leakage
  • Duct efficiency
  • Forced-air
  • Heating system
  • In-situ measurements
  • Manufactured homes
  • Single-family homes

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • Mechanical Engineering
  • Electrical and Electronic Engineering


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