PA Energy Code PA Check

Envelope Requirements

The prescriptive tables in the 2015 IRC/IECC prescribe minimum acceptable insulation and fenestration performance levels based on geographic area. 

If a builder chooses the prescriptive path, these requirements must simply be met.  If a performance path is chosen, the overall energy use of the building must be equal to or better than if the house had been built to these requirements.

In PA, builders also have the option of selecting the less restrictive prescriptive requirements in the "PA Residential Alternative Energy Provisions" (RAEP), as long as they also agree to implement one of the "Enhanced Measures" listed in that document.

Here is a comparison of the prior (2009 IECC) requirements to the current IRC/IECC requirements, as well as the RAEP.  2015 IRC/IECC changes are highlighted in Yellow.  Changes that apply only to the RAEP are in white.

Climate Zone 4 - Southeast PA

Zone 4 IECC Requirements

Skylights: must now meet a more stringent U-factor requirement of 0.55.

Windows:  must now meet a Solar Heat Gain Requirement of 0.40.  (There was previously no requirement.)

Ceilings:  must now be insulated to R-49, unless the RAEP pathway is selected.

Framed Walls:  there are now two choices (1) build from 2x4's, insulate the cavities to R13, and add R-5 exterior continuous insulation OR (2) build from 2x6's and insulate the cavities to R-20.

PA Amendment:  If 2x6's are used and the "framing factor" (% of wall area that is wood framing) is 20% or less, or the nominal stud spacing is 24" on-center, R-18 can be installed instead of R-20.

REAP Detail:  If 2x4's are used and structural sheating covers 40% or less of the exterior, the exterior insulation can be reduced to R-3 in the areas without sheathing to maintain a constant thickness.

Climate Zone 5 - Central PA

Zone 5 IECC Requirements

Skylights: must now meet a more stringent U-factor requirement of 0.55.

Windows:  must now meet a more stringent U-factor requirement of 0.32

Ceilings:  must now be insulated to R-49

Wall PA Amendment:  If 2x6's are used and the "framing factor" (% of wall area that is wood framing) is 20% or less, or the nominal stud spacing is 24" on-center, R-18 can be installed instead of R-20.

Wall REAP-only Detail:  If 2x4's are used and structural sheating covers 40% or less of the exterior, the exterior insulation can be reduced to R-3 in the areas without sheathing to maintain a constant thickness.

Basement and Crawlspace Walls:  must now meet more stringent insulation requirements of R-15 continuous or R-19 in cavities, unless the REAP pathway is selected.

Floor REAP-only Detail: Floor insulation may be reduced to R-19 if the floor is over an unconditioned basement.

Climate Zone 6 - Northern PA

Zone 4 IECC Requirements

Skylights: must now meet a more stringent U-factor requirement of 0.55.

Windows:  must now meet a more stringent U-factor requirement of 0.32

Framed Walls:  there are now three choices (1) build from 2x4's, insulate the cavities to R13, and add R-10 exterior continuous insulation OR (2) build from 2x6's and insulate the cavities to R-23 (this will probably require mineral wool) OR:

Wall PA Amendment:  (3) build from 2x6's, insulate the cavities to R18, and add R-6.5 exterior continuous insulation

Basement Wall REAP-only Detail:  R-10 continuous or R-13 in cavities is allowed.

Floor REAP-only Detail: Floor insulation may be reduced to R-19 if the floor is over an unconditioned basement.

Ceilings with Buried Ducts

A provision was adopted from the 2018 IECC that requires R-8 duct insulation, plus ceiling insulation above and below the ducts that totals at least R-19, excluding the value of the duct insulation.

Buried Duct Diagram

Insulated Siding

The 2015 IRC/IECC added a requirement that the R-value of insulated siding be reduced by R-0.6 from the manufacturer's lableled value.

 

Climate Zones

The IRC/IECC divides the country into 8 climate zones that are used to apply different insulation and fenstration requirements.

PA is divided into 3 zones:

North PA:  Zone 6

Central PA:  Zone 5

Southeast PA:  Zone 4

PA Climate Zone Map