Wash. Admin. Code § 51-11R-40552
TABLE R405.4.2(2)
DEFAULT DISTRIBUTION SYSTEM EFFICIENCIES FOR PROPOSED DESIGNSa
DISTRIBUTION SYSTEM CONFIGURATION AND CONDITION | DISTRIBUTION SYSTEM EFFICIENCY |
Distribution system components located in unconditioned space | 0.88 |
Distribution systems entirely located in conditioned spaceb | 0.93 |
Zonal systemsc | 1.00 |
For SI: 1 cubic foot per minute = 0.47 L/s, 1 square foot = 0.093m2, 1 pound per square inch = 6895 Pa, 1 inch water gauge = 1250 Pa.
a Values given by this table are for distribution systems, which must still meet all prescriptive requirements for duct and pipe system insulation and leakage.
b Entire system in conditioned space shall mean that no component of the distribution system, including the air-handler unit, is located outside of the conditioned space. All components must be located on the interior side of the thermal envelope (inside the insulation) and also inside of the air barrier. Refrigerant compressors and piping are allowed to be located outside.
c Zonal systems are systems where the heat source is located within each room. Systems shall be allowed to have forced airflow across a coil but shall not have any ducted airflow external to the manufacturer's air-handler enclosure. Hydronic systems do not qualify.
Wash. Admin. Code § 51-11R-40552
Statutory Authority: RCW 19.27A.020, 19.27A.045 and chapters 19.27 and 34.05 RCW. 13-04-055, § 51-11R-40552, filed 2/1/13, effective 7/1/13.