Section 408.31065. Equivalent U-Factors.

Rule 1065. Section R402.1.4 and table R402.1.3 of the code are amended to read as follows:

Table R402.1.3 Equivalent U-Factorsa

Climate  Zone	Fenestratio n U-Factor	Skylight U- Factor	Ceiling U- Factor	Frame Wall U- Factor	Mass wall U-Factor b	Floor U-Factor	Basemen tWall U-Factor	Crawl Space Wall U- Factor
5A	0.32	0.55	0.030	0.057	0.082	0.033	0.059	0.055
6A	0.32	0.55	0.026	0.057	0.060	0.033	0.050	0.055
7	0.32	0.55	0.026	0.057	0.057	0.028	0.050	0.055

a.     Nonfenestration U-factors shall be obtained from measurement, calculation, or an approved source.

b.      When more than half the insulation is on the interior, the mass wall U-factors shall be a maximum of 0.065 in zone 5 and marine 4, and 0.057 in zones 6 and 7.

R402.1.4 Total UA alternative. If the total building thermal envelope UA (sum of U- factor times assembly area) is less than or equal to the total UA resulting from using the U-factors in Table R402.1.3 (multiplied by the same assembly area as in the proposed building), the building shall be considered in compliance with Table R402.1.1. The UA calculation shall be done using a method consistent with the ASHRAE Handbook of Fundamentals and shall include the thermal bridging effects of framing materials.

History: 1998-2000 AACS; 2008 AACS; 2010 AACS; 2015 AACS.