ASHRAE-90.1-2022- - Page 049
Extracted Content
Table 5.5.3.1.4 Increased Roof Insulation Levels
Roofs Nonresidential Residential
Opaque Elements
Assembly Maximum
Insulation Min. R-Value
Climate Zone 0
Assembly Maximum
Insulation Min. R-Value
Insulation entirely above deck U-0.027 R-36 c.i. U-0.027 R-36 c.i.
Metal buildings U-0.028 R-35
Climate Zones 1 to 3
Insulation entirely above deck U-0.030 R-33 c.i. U-0.029 R-34 c.i.
Metal buildings U-0.028 R-35
demonstrated by testing or calculations representative of the designed assembly in accordance with Normative Appendix A, Section A9.1 where approved by the code official . 2. For multiple assemblies within a single class of construction for a single space conditioning cate- gory, compliance shall be shown for either (a) the most restrictive requirement or (b) an areaweighted average U-factor, C-factor, or F-factor .
5.5.3.1 Roofs 5.5.3.1.1 All roofs shall comply with the insulation values specified in Tables 5.5-0 through 5.5-8. 5.5.3.1.2 Roof Curbs. Skylight and other roof curbs shall be insulated to not less than R-5.0. 5.5.3.1.3 Joints in Roof Insulation. Joints in the insulation shall be installed in accordance with Section 5.8.1.10.
5.5.3.1.4 Roof Solar Reflectance and Thermal Emittance. Roofs in Climat e Zones 0 through 3 s hall have one of the following:
a. A minimum three-year-aged solar reflectance of 0.55 and a minimum three-year-aged thermal emittance
of 0.75 when tested in accordance with CRRC S100. b. A minimum Solar Reflectance Index of 64 when determined in accordance with the Solar Reflectance
Index method in ASTM E1980 using a convection coefficient of 2.1 Btu/h·ft [2] ·°F, based on three-yearaged solar reflectance and three-year-aged thermal emittance tested in accordance with CRRC S100. c. Increased roof insulation levels found in Table 5.5.3.1.4.
The values for three-year-aged solar reflectance and three-year-aged thermal emittance shall be determined by a laboratory accredited by a nationally recognized accreditation organization and shall be labeled and certified by the manufacturer .
Exceptions to 5.5.3.1.4:
- Ballasted roofs with a minimum stone ballast of 17 lb/ft [2 ] or 23 lb/ft [2] pavers.
- Vegetative roof systems that contain a minimum thickness of 2.5 in. of growing medium and covering a minimum of 75% of the roof area with durable plantings.
- Roofs where a minimum of 75% of the roof area a. is shaded during the peak sun angle on June 21 by permanent components or features of the
building ; b. is covered by offset photovoltaic arrays, building -integrated photovoltaic arrays, or solar air
or water collectors; or c. is permitted to be interpolated using a combination of 1 and 2 above. 4. Steep-sloped roofs . 5. Low-sloped metal building roofs in Climate Zones 2 and 3. 6. Roofs over ventilated attics, roofs over semiheated spaces, or roofs over conditioned spaces that are not cooled spaces . 7. Asphaltic membranes in Climate Zones 2 and 3.
5.5.3.1.5 Insulated Metal Panels. The U-factor of roof assemblies that include insulated metal panels shall not be greater than the U-factors of Tables 5.5-0 through 5.5-8 for the applicable class of construction . U-factors of insulated metal panels shall be determined in accordance with Section A9.4.7.
ANSI/ASHRAE/IES Standard 90.1-2022 (I-P) 47