Understanding Wisconsin's New Energy Code Requirements
January 14, 2026
Wisconsin updated its energy code (SPS 363) effective January 1, 2026, adopting provisions based on the 2021 International Energy Conservation Code (IECC) with state-specific amendments. This is the first energy code update since Wisconsin adopted provisions based on the 2015 IECC in 2018. The updated code applies to all new construction and additions; existing buildings undergoing renovations are subject to the energy code only when the renovation scope exceeds 50% of the building's conditioned floor area.
Residential Energy Code Changes (SPS 363.04–.06)
For residential construction in Climate Zone 6 (most of Wisconsin) and Climate Zone 7 (northern Wisconsin), the key changes are: Ceiling insulation increases from R-49 to R-60 in Climate Zone 7 and remains R-49 in Climate Zone 6. Wall insulation for wood-frame construction increases from R-20 (or R-13 + R-5 continuous) to R-20 + R-5 continuous in Climate Zone 7. Foundation wall insulation increases from R-15 to R-20 in Climate Zone 7. Air barrier requirements now mandate third-party verification testing (blower door) at 3.0 ACH50 maximum (previously 5.0 ACH50) for all new residential construction.
Commercial Energy Code Changes (SPS 363.07–.09)
Commercial buildings see the most significant changes in HVAC system efficiency requirements and lighting power density allowances. Rooftop units must now meet or exceed 15 SEER / 12.2 EER for cooling and 81% AFUE for gas heating — up from 14 SEER / 11.2 EER and 80% AFUE. Interior lighting power density allowances have been reduced by approximately 10% across all occupancy types. New requirements for automatic lighting shutoff in commercial spaces over 5,000 square feet have been added. Envelope requirements for commercial buildings now include a mandatory R-30 continuous insulation requirement for above-grade mass walls (previously R-25).
Documentation and Compliance
One of the most practical changes is the new compliance documentation requirement. Builders must now submit an energy compliance report (REScheck or COMcheck) with every permit application for new construction and additions. Previously, this was required only in Milwaukee, Madison, and a handful of other municipalities — now it applies statewide. The compliance report must be prepared by a licensed design professional or a certified energy rater. Third-party blower door testing for residential construction must be conducted by a HERS rater or equivalent certified professional.
Cost Impact
DSPS estimates the updated energy code will add $3,500–$7,000 to the construction cost of a typical single-family home in Climate Zone 6 and $5,000–$9,500 in Climate Zone 7, primarily from increased insulation, air sealing requirements, and blower door testing. For commercial construction, the estimated impact is 1.5–3.0% of total construction cost, with the largest cost increases in lighting system upgrades and HVAC efficiency requirements. Energy modeling studies project these additional costs will be offset by energy savings within 5–8 years for residential and 4–6 years for commercial buildings.
Exemptions and Alternatives
The updated code includes a total building performance alternative (SPS 363.06(6)) that allows builders to demonstrate overall energy performance equivalent to or better than prescriptive requirements using approved energy modeling software. This is particularly useful for designs that exceed code in some areas but fall short in others — for example, a building with extensive south-facing glazing that exceeds window-to-wall ratio limits but achieves net-zero energy through solar PV and heat pump systems. Agricultural buildings remain exempt from the energy code under SPS 363.02(2).
Data note: The permit data referenced in this article was verified against official municipal sources as of February 2026. Fee schedules and requirements can change at any time. Always confirm current requirements directly with your local permit office before submitting applications. Use our Fee Calculator to get the latest fee estimates for your specific jurisdiction and project type.
Frequently asked questions
What are Wisconsin's new residential insulation requirements?
Under the updated SPS 363 (effective January 1, 2026): Climate Zone 7 (northern WI) requires R-60 ceiling, R-20+R-5 wall, and R-20 foundation insulation. Climate Zone 6 (most of WI) requires R-49 ceiling, R-20 or R-13+R-5 wall. Air leakage testing is now mandatory at 3.0 ACH50 maximum for all new residential construction.
Do I need a blower door test for new construction in Wisconsin?
Yes, effective January 1, 2026. All new residential construction in Wisconsin must pass a blower door test at 3.0 ACH50 maximum (previously 5.0 ACH50). The test must be conducted by a certified HERS rater or equivalent professional. This applies statewide, not just in municipalities that previously required it.
How much does the new Wisconsin energy code add to construction costs?
DSPS estimates $3,500–$7,000 additional cost for a typical single-family home in Climate Zone 6 and $5,000–$9,500 in Climate Zone 7. Commercial construction costs increase an estimated 1.5–3.0%. These costs are projected to be offset by energy savings within 5–8 years (residential) or 4–6 years (commercial).
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