WAC 51-11-1004   Section 1004: Floors over unconditioned space.

     1004.1 General: Tables 10-3, 10-4 and 10-4a list heat-loss coefficients for floors over unconditioned spaces in units of Btu/h•ft²•°F.

     They are derived from procedures listed in RS-1, listed in Chapter 7, assuming an average outdoor temperature of 45°F, an average indoor temperature of 65°F, and a crawlspace area of 1350 ft² and 100 ft of perimeter. The crawlspace is assumed to be 2.5 feet high, with 24 inches below grade and 6 inches above grade.

     1004.2 Crawlspace Description: Four configurations are considered: Naturally ventilated crawlspace, mechanically ventilated crawlspace, heated plenum crawlspace and exposed floor.

     Naturally ventilated crawlspaces: Assumed to have 3.0 air-changes per hour, with at least 1.0 ft² of net-free ventilation in the foundation for every three hundred ft² of crawlspace floor area. The crawlspace is not actively heated.

     Floors over unheated areas, such as garages, may only use those values which have R-0 perimeter insulation.

     Mechanically ventilated crawlspaces: Assumed to have 1.5 air changes per hour, with less than 1.0 ft² of net-free ventilation in the foundation for every three hundred ft² of crawlspace floor area. The crawlspace is not actively heated. Floors over unheated basements may only use those values which have R-0 perimeter insulation.

     Heated-plenum crawlspaces: Assumed to have 0.25 air-changes per hour, with no foundation vents. Heated supply air from central furnace is blown into a crawlspace and allowed to enter the living space unducted via holes cut into the floor.

     Enclosed floors: Assumes no buffer space, and a covering of one-half inch of T1-11 on the exterior of the cavity exposed to the outside air or rigid insulation below a concrete floor, such as over parking garages.

     1004.3 Construction Description: Floors are assumed to be either joisted floors framed on sixteen inch centers, or post and beam on four by eight foot squares. Insulation is assumed to be installed under the subflooring between the joists or beams with no space between the insulation and the subfloor. Insulation is assumed to be uncompressed. Exposed floors also include concrete with continuous rigid insulation assumed.

     Perimeter insulation is assumed to extend from the top of the rim joist to the crawlspace floor and then inward along the ground (on top of the ground cover) for at least twenty-four inches.

     Floor coverings are assumed to be light carpet with rubber pad.

TABLE 10-3

DEFAULT U-FACTORS FOR FLOORS OVER VENTED CRAWLSPACE OR

UNHEATED BASEMENT

Nominal R-value		U-factor
Floor	Perimeter	Post & Beam	Joists
0	0 11 19 30	0.112 0.100 0.098 0.093	0.134 0.116 0.114 0.107
11	0 11	0.052 0.048	0.056 0.052
19	0 11	0.038 0.036	0.041 0.038
22	0 11	0.034 0.033	0.037 0.035
25	0 11	0.032 0.031	0.034 0.033
30	0 11	0.028 0.027	0.029 0.028
38	0 11	0.024 0.024	0.025 0.024

TABLE 10-4

DEFAULT U-FACTORS FOR FLOORS OVER HEATED PLENUM CRAWLSPACES

Nominal R-value Perimeter	U-factor
11	0.085
19	0.075
30	0.069

TABLE 10-4A

EXPOSED FLOOR

Nominal R-value	U-factor
Nominal R-value	Concrete	Wood Joist	Metal Joist
R-11	0.077	0.088	0.14
R-15	0.059	0.076	0.12
R-19	0.048	0.062	0.11
R-21	0.043	0.057	0.11
R-25	0.037	0.051	0.10
R-30	0.031	0.040	0.09
R-38	0.025	0.034	0.08

Note:

Crawlspaces used as heated plenums have approximately 30% higher heat-loss rate than unvented crawlspaces with the same assumed ACH. Default U-values in Table 10-4 reflect this higher rate of heat loss.

[Statutory Authority: RCW 19.27A.025, 19.27A.045. 10-03-115, 10-13-113 and 10-22-056, § 51-11-1004, filed 1/20/10, 6/21/10 and 10/28/10, effective 1/1/11. Statutory Authority: RCW 19.27A.020, 19.27A.045. 04-01-106, § 51-11-1004, filed 12/17/03, effective 7/1/04. Statutory Authority: RCW 19.27A.025, 19.27A.045. 01-03-010, § 51-11-1004, filed 1/5/01, effective 7/1/01; 98-03-003, § 51-11-1004, filed 1/8/98, effective 7/1/98. Statutory Authority: RCW 19.27A.020 and 1990 c 2. 91-01-112, § 51-11-1004, filed 12/19/90, effective 7/1/91.]

NOTES:

     Reviser's note:  Notice of Objection: The Joint Administrative Rules Review Committee (Committee) finds that, in adopting the 2009 proposed changes to the State Energy Code, Chapter 51-11 WAC, on November 20, 2009, the State Building Code Council (Council) failed to comply with all requirements of the law and failed to adequately respond to the Committee's request for additional economic impact and cost-benefit analyses prior to adoption.

     On October 1, 2009, the Committee found that the Small Business Economic Impact Statement (SBEIS) for the proposed changes filed with the Code Reviser failed to comply with all requirements of law. The Committee requested that the Council conduct a cost-benefit analysis pursuant to RCW 34.05.328 and amend the SBEIS to provide additional economic impact information, including an estimate of the number of jobs that would be created or lost as a result of compliance with all the proposed rules, as required by RCW 19.85.040 (2)(d).

     The Council provided the Committee with information and data on November 18, 2009. On December 2, 2009, the Committee found that the Council failed to adequately respond to the Committee's request for additional data. Specifically, the Committee found that the Council failed to amend the SBEIS to (a) estimate the number of jobs that would be created or lost as a result of compliance with the proposed changes; and (b) support the SBEIS with a detailed and rigorous costs analysis of the cumulative impact of all the changes. In addition, the Committee found that the Council failed to provide the Committee with a cost-benefit analysis of the proposed changes and pursuant to the requirements of RCW 34.05.328.

     The Committee strongly supports a process that makes thoughtful and informed progress towards changes that result in improved energy efficiency in our buildings, wherever practicable. While the Council worked diligently, it is the opinion of the Committee that the Council did not fully develop and consider the economic impacts and costs versus benefits of these significant changes to our Energy Code. Furthermore, it is the opinion of the Committee that the Council and the Legislature need this information to fully evaluate the value, impacts, and consequences of the proposed codes, with due diligence to their respective fiduciary responsibilities, in order to create the best informed public policy.

     As a result, the Committee recommends that the Governor suspend the adoption and implementation of the changes to the Energy Code, Chapter 51-11 WAC, adopted by the Council on November 20, 2009, until such time as a more adequate analysis has been completed and considered by the appropriate bodies.

     For all of the above stated reasons, the Committee objects to the changes to the State Energy Code, Chapter 51-11 WAC, that were adopted by the Council on November 20, 2009, and hereby directs the Code Reviser, pursuant to RCW 34.05.640(4), to publish this Notice of Objection in the Washington State Register and along with any publication in the Washington Administrative Code of changes to Chapter 51-11 WAC that were adopted by the Council in 2009 and filed with the Code Reviser.