// CODE SNIPPET

# A3.1.3 Mass Wall U-factor

JUMP TO FULL CODE CHAPTER

*U-factors* for *mass walls* shall be taken from Table A3.1-1 or determined by the procedure in this subsection. It is acceptable to use the *U-factors* in Table A3.1-1 for all *mass walls*, provided that the grouting is equal to or less than that specified. *HC* for *mass walls* shall be taken from Table A3.1-2 or A3.1-3.

If not taken from Table A3.1-1, *mass wall U-factors* shall be determined from Tables A3.1-2, A3.1-3, or A3.1-4 using the following procedure:

- If the
*mass wall*is uninsulated or only the cells are insulated:- For concrete
*walls*, determine the*U-factor*from Table A3.1-2 based on the concrete density and*wall*thickness. - For concrete block
*walls*, determine the*U-factor*from Table A3.1-3 based on the block size, concrete density, degree of grouting in the cells, and whether the cells are insulated.

- For concrete
- If the
*mass wall*has additional insulation:- For concrete
*walls*, determine the*R*from Table A3.1-2 based on the concrete density and_{c}*wall*thickness. Next, determine the effective*R-value*for the insulation/framing layer from Table A3.1-4 based on the*rated R-value of insulation*installed, the thickness of the insulation, and whether it is installed between wood or*metal framing*or with no framing. Then, determine the*U-factor*by adding the*R*and the effective_{u}*R-value*together and taking the inverse of the total. - For concrete block
*walls*, determine the*R*from Table A3.1-3 based on the block size, concrete density, degree of grouting in the cells, and whether the cells are insulated. Next, determine the effective_{u}*R-value*for the insulation/framing layer from Table A3.1-4 based on the*rated R-value of insulation*installed, the thickness of the insulation, and whether it is installed between wood or*metal framing*or with no framing. Then, determine the*U-factor*by adding the*R*and the effective_{u}*R-value*together and taking the inverse of the total.

- For concrete

### Related Code Sections

A3.1.3 Normative Appendix A Rated R-Value of Insulation and Assembly U-factor, C-Factor, and F-Factor Determinations, Mass Wall U-factor

*U*-

*factors*for

*mass*

*walls*shall be taken from Table A3.1-1 or determined by the procedure in this subsection. It is acceptable to use the

*U*...

Energy Standard for Buildings Except Low-Rise Residential Buildings 2016 of Illinois > Normative Appendix A Rated R-Value of Insulation and Assembly U-factor, C-Factor, and F-Factor Determinations > A3 Above-Grade Walls > A3.1 Mass Wall > A3.1.3 Mass Wall U-factor

R402.1.4 [RE] Residential Energy Efficiency,

*U*-factor Alternative*U*-

*FACTOR*

*MASS*

*WALL*

*U*-

*FACTOR*b FLOOR

*U*-

*FACTOR*BASEMENT

*WALL*

*U*-

*FACTOR*CRAWL SPACE

*WALL*

*U*-

*FACTOR*1 0.50 0.75 0.035 ...

2018 Illinois Energy Conservation Code Standards for Privately Funded Commercial Facilities and Standards for Residential Buildings > 4 [RE] Residential Energy Efficiency > R402 Building Thermal Envelope > R402.1 General (Prescriptive) > R402.1.4

*U*-factor Alternative
R402.1 [RE] Residential Energy Efficiency, General (Prescriptive)

*U*-

*FACTOR*GLAZED FENESTRATION SHGC b, e CEILING R -VALUE WOOD FRAME

*WALL*R -VALUE

*MASS*

*WALL*R -VALUE i FLOOR R -VALUE ...

2018 Illinois Energy Conservation Code Standards for Privately Funded Commercial Facilities and Standards for Residential Buildings > 4 [RE] Residential Energy Efficiency > R402 Building Thermal Envelope > R402.1 General (Prescriptive)

A5.2.3 Normative Appendix A Rated R-Value of Insulation and Assembly U-factor, C-Factor, and F-Factor Determinations, U-Factors for Mass Floors

The

*U*-*factors*for*mass**walls*shall be taken from Table A5.2.3.1 . Table A5.2.3.1 Assembly*U*-*Factors*for*Mass*Floors Framing ...
Energy Standard for Buildings Except Low-Rise Residential Buildings 2016 of Illinois > Normative Appendix A Rated R-Value of Insulation and Assembly U-factor, C-Factor, and F-Factor Determinations > A5 Floors > A5.2 Mass Floors > A5.2.3 U-Factors for Mass Floors

C402.1.4 [CE] Commercial Energy Efficiency, Assembly

*U*-factor,*C*-Factor or*F*-Factor-Based Method
are below grade, below-grade

*walls*shall comply with the*U*-*factor*requirements for above-grade*mass**walls*. "*Mass*floors" shall be in accordance ...
2018 Illinois Energy Conservation Code Standards for Privately Funded Commercial Facilities and Standards for Residential Buildings > 4 [CE] Commercial Energy Efficiency > C402 Building Envelope Requirements > C402.1 General (Prescriptive) > C402.1.4 Assembly

*U*-factor,*C*-Factor or*F*-Factor-Based Method