Secondary Author(s)

Fenaughty, Karen; Sonne, Jeffrey

Report Number




Attics; Ducts; Humidity; Energy Efficiency; Ventilation


This research project evaluated cooling energy and moisture-related impacts between conventional attic venting and sealed attic vents in a lab home located in central Florida. All tests had R30 insulation on the ceiling and the roof deck uninsulated. A total of four different test configurations were tested. The four tested configurations were: Attic Vented with Attic Ducts, Attic Vents Sealed with Attic Ducts, Attic Vented with Indoor Ducts, and Attic Vents Sealed with Indoor Ducts. On average the impact from sealing attic vents will increase annual cooling energy use in a Florida home between 5%-10%. For a 1620 square foot home with R30 ceiling insulation, this would equate to an increased annual energy cost of approximately $25 to $54 (@$0.12/kWh). This research evaluation was conducted over a relatively mild central Florida winter. Given the observed trends of increased potential roof deck moisture issues at colder temperatures, further research conducted under cooler outdoor temperatures is warranted to develop a fuller expectation of potential moisture issues for the sealed vent configuration described in this report before accepting this particular sealed attic vent practice into code.

Date Published


Local Subjects

Buildings - Attics; Buildings - Ducts; Buildings - Energy Efficiency; Humidity; Buildings - Ventilation


FSEC Energy Research Center® Collection



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