Secondary Author(s)

Withers Jr., Charles

Report Number

FSEC-RR-140-06

URL

http://publications.energyresearch.ucf.edu/wp-content/uploads/2018/06/FSEC-RR-140-06.pdf

Keywords

Buildings; Ducts; HVAC; Return air systems; Indoor air quality; Residential HVAC; Energy efficiency; Air pressure imbalances

Abstract

Field research performed in 70 central Florida homes found that return grills are almost always located in the central zone of the house, and that individual rooms rarely have ducted return air or return transfer pathways. When interior doors were closed, the closed rooms went to +0.0249 inches of water gauge (in w.g.) (+6.2 pascals (Pa)) wrt outdoors (wrt = with respect to), and the central zone went to -0.0116 in w.g. (-2.9 Pa) wrt outdoors. Room pressures as high as +0.150 in w.g. (+37.3 Pa) and central zone pressure as low as -0.059 in w.g. (-14.7 Pa) wrt outdoors were found. These pressures create exfiltration from the closed rooms and infiltration in the central zone. With the air handler operating, the house infiltration rates increased, on average, from 0.46 to 0.60 air changes per hour when all interior doors were closed. According to homeowner reports, interior doors are closed 11% of the time, on average. These pressures and increased infiltration rates impact indoor air quality, indoor relative humidity, energy use, peak electrical demand, comfort, and system sizing.

Date Published

1-1-2006

Identifiers

511

Notes

Reference Publication: James B. Cummings and Charles R. Withers, Jr.. "Unbalanced Return Air in Residences: Causes, Consequences, and Solutions". ASHRAE Transactions Vol 112, Part 1, January 2006.

Subjects

Air quality management; Energy consumption; Buildings--Energy conservation; Indoor air pollution

Local Subjects

Buildings - Ducts; Buildings - HVAC

Type

Text; Document

Collection

FSEC Energy Research Center® Collection

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