At least eight major US jurisdictions now legally require reflective cool roofs on new and re-roofed buildings, and the binding number in almost every rule is a single figure: the roof’s solar reflectance. Across the mandates examined here, the required low-slope reflectance floor clusters between 0.55 and 0.72, meaning a compliant flat commercial roof must bounce back at least 55 to 72 percent of incoming sunlight. Chicago sets the single strictest initial threshold at 0.72 (City of Chicago Municipal Code 18-13, effective April 2009), while California’s Title 24 is the only mandate broad enough to reach re-roofing jobs on existing single-family homes statewide (California Energy Commission, 2025 code effective January 2026).
This report compiles the reflective-roof mandates in force as of July 2026, ranks them by stringency, and explains what each one actually requires a roofer to install. Every figure is cited to a named code or agency and year.
Headline finding: the cool roof mandate map is small, urban, and built on one number
Reflective-roof mandates in the United States are concentrated in hot-climate states and dense cities, they overwhelmingly target low-slope commercial roofs, and nearly all of them hinge on a solar reflectance threshold rather than material type. Of the jurisdictions tracked here, Chicago (0.72 initial), New York City (0.70 initial), and Philadelphia (0.65 initial) impose the highest low-slope reflectance floors, while California’s Title 24 (aged 0.63 for low-slope) is the widest in scope because it applies statewide to residential and nonresidential re-roofing in most climate zones.
The practical takeaway for building owners and contractors: in these places the roof color decision is not aesthetic, it is a code requirement, and a dark membrane or dark shingle on a covered low-slope roof will fail inspection unless an exemption applies.
What counts as a cool roof, and why solar reflectance is the number that matters
A cool roof is a roof surface engineered to reflect more sunlight and shed absorbed heat, measured by two radiative properties: solar reflectance (the fraction of solar energy reflected, from 0 to 1) and thermal emittance (how efficiently the surface releases absorbed heat, from 0 to 1), per the Cool Roof Rating Council (CRRC, 2026). Codes usually also cite the Solar Reflectance Index (SRI), a combined 0-to-100+ scale defined by ASTM E1980.
Reflectance is the number that carries most mandates because it governs how much heat the roof absorbs in the first place. The CRRC rates products for both initial values and values aged three years at outdoor test farms in Arizona, Ohio, and Florida, because reflectance degrades from soiling, biological growth, and UV exposure (CRRC, 2026). That is why some codes cite a lower aged threshold alongside a higher initial one: a fresh white membrane near 0.80 reflectance can weather down toward 0.55 within three years. Reflectance also drives the energy-efficient roof color choices building owners weigh even where no mandate applies.
Which US cities and states mandate reflective roofs (2026 tracker)
The table below ranks the eight tracked mandates by low-slope stringency, using the initial solar reflectance floor where a code sets one and the aged value where it does not. Thresholds, scope, and effective dates are drawn directly from each jurisdiction’s code and from the CRRC codes database (2026). “Low-slope” means a roof pitch under 2:12, where most cool roof rules concentrate.
| Jurisdiction | Low-slope reflectance requirement | Steep-slope requirement | Scope | In force since | Source (year) |
|---|---|---|---|---|---|
| Chicago, IL | Initial SR ≥ 0.72, or 3-year aged SR ≥ 0.50 | Not mandated (low-slope focus) | New low-slope roofs and full/partial replacements over conditioned space | April 2009 | Chicago Municipal Code 18-13; CRRC (2026) |
| New York City, NY | Initial SR ≥ 0.70 and TE ≥ 0.75, or SRI ≥ 82; 75% of roof area | Initial SR ≥ 0.25 or SRI ≥ 39 | New and substantially renovated low-slope roofs | 2009, expanded 2011 | NYC Energy Conservation Code; Smart Surfaces Policy Tracker (2024) |
| Philadelphia, PA | Initial SR ≥ 0.65; 3-year aged SRI ≥ 64 or initial SRI ≥ 82 | Not mandated (low-slope focus) | New buildings, additions, and roof rebuilds over conditioned low-slope space | 2010 | Philadelphia Energy Efficiency Regulation 17-111 (2020) |
| California (statewide, Title 24) | Aged SR ≥ 0.63 and TE ≥ 0.75, or SRI ≥ 75 (climate zones 2, 4, 6-15) | Aged SR 0.20-0.25 or SRI 16-23 (climate zones 10-15) | New construction, additions, and alterations including re-roofing; residential and nonresidential | 2025 code, effective Jan 2026 | California Energy Commission; CRRC (2026) |
| ASHRAE 90.1 (model code) | Aged SR ≥ 0.55 and TE ≥ 0.75, or SRI ≥ 64 (climate zones 0-3) | Not mandated | Commercial low-slope roofs where the standard is adopted | Varies by state adoption | ANSI/ASHRAE/IES 90.1; CRRC (2026) |
| Los Angeles, CA (city) | Above Title 24 baseline; flat-roof SRI raised in 2018 | Aged SR ≥ 0.25 (raised from 0.20 in 2018) | New residential low-rise construction | 2014, tightened 2018 | LA Ordinance 183149; Smart Surfaces Policy Tracker (2024) |
| Denver, CO | Cool roof (SRI thresholds) plus one additional green measure | Not separately mandated | New buildings and re-roofs on buildings 25,000 sq ft and larger | 2018-2019 | Denver Green Buildings Ordinance (2019) |
| Texas metros (IECC 2021) | Follows IECC/ASHRAE prescriptive path where adopted | SR ≥ 0.25 (steep-slope, climate zones 2-3) | New construction in adopting cities (Houston, Dallas, others) | 2021 code adoption | IECC 2021, climate zones 2-3 |
Chicago and New York set the strictest reflectance floors
Chicago imposes the highest single initial reflectance requirement of any tracked jurisdiction: low-slope roofs permitted on or after April 22, 2009 must use products with an initial reflectance of at least 0.72, or a three-year aged reflectance of at least 0.50 (Chicago Municipal Code 18-13, 2026). New York City is close behind, requiring an initial solar reflectance of 0.70 with thermal emittance of at least 0.75, or an SRI of 82, across at least 75 percent of a new or substantially renovated low-slope roof (NYC Energy Conservation Code; Smart Surfaces Policy Tracker, 2024).
Both cities carve out exemptions. Chicago drops the requirement to a minimum reflectance of 0.30 where more than half the low-slope roof is covered by a qualifying vegetated green roof (Chicago Municipal Code 18-13, 2026). These are heat-island rules first: the stated purpose is to cut rooftop surface temperatures in dense, paved urban cores.
California’s Title 24 is the widest-reaching mandate
California’s Title 24, Part 6 energy code is the only mandate tracked here that applies statewide and reaches re-roofing on existing single-family homes, not just new commercial construction. The 2025 code, effective January 1, 2026, requires low-slope roofs in climate zones 2, 4, and 6 through 15 to have an aged solar reflectance of at least 0.63 and thermal emittance of at least 0.75, or an SRI of 75 (California Energy Commission; CRRC, 2026).
Steep-slope residential roofs face lower but still binding thresholds in the hotter inland zones: an aged solar reflectance of 0.25 or SRI 23 in climate zones 10, 11, 13, and 15, and 0.20 or SRI 16 in zones 12 and 14 (CRRC, 2026). Because the rule explicitly covers “alterations including roof recoverings,” a California homeowner re-roofing a house in a covered climate zone may be required to install a rated cool product, subject to prescriptive exemptions and the performance-compliance alternative.
Where reflective roofs are not required
Most of the United States has no cool roof mandate at all. Outside California’s statewide code and the named cities, reflective-roof requirements generally appear only where a jurisdiction has adopted ASHRAE 90.1 or the IECC commercial provisions, a patchwork documented in our state roofing code and licensing report, which apply cool roof rules to low-slope commercial roofs in the hottest climate zones (0 through 3) and leave steep-slope residential roofs largely unregulated (ANSI/ASHRAE/IES 90.1; CRRC, 2026).
Cold-climate states rarely mandate reflectivity, because a highly reflective roof can slightly raise winter heating demand, a tradeoff building scientists call the “heating penalty.” That is why nearly every mandate in the tracker sits in a hot or mixed climate zone, and why the map of required reflective roofs looks like a map of southern and coastal-urban America rather than the country as a whole.
What a compliant cool roof looks like on the job
On a low-slope commercial roof, compliance usually means a white or light-gray single-ply membrane (TPO or PVC), a reflective coating over an existing membrane, or a light-colored modified-bitumen cap sheet, all carrying a CRRC product label that documents the rated reflectance and emittance. The label is what an inspector checks against the code threshold (CRRC, 2026).
- Identify the roof slope and climate zone. Under 2:12 pitch triggers the stricter low-slope thresholds; the climate zone determines whether the rule applies at all.
- Match a CRRC-rated product to the local threshold. Compare the product’s aged reflectance and emittance (or SRI) to the jurisdiction’s minimum before ordering.
- Confirm the compliance path. Most codes offer a prescriptive reflectance path and a performance/energy-modeling alternative that can allow a non-cool roof if the whole building meets an energy target.
- Document for inspection. Keep the CRRC label and product data on site; the reflectance value on the label is the number that clears or fails the roof.
Methodology
This tracker compiles reflective-roof mandates in force as of July 2026 from primary regulatory sources: the California Energy Commission’s Title 24 Part 6 standards, municipal energy and building codes for Chicago, New York City, Philadelphia, Los Angeles, and Denver, the ANSI/ASHRAE/IES Standard 90.1 model energy standard, and the International Energy Conservation Code (IECC) 2021. Threshold values were cross-checked against the Cool Roof Rating Council codes and programs database (2026) and the Smart Surfaces Policy Tracker (2024). Jurisdictions are ranked by low-slope stringency using each code’s stated solar reflectance floor, preferring the initial value where a code specifies one and the aged value where it does not. Solar reflectance, thermal emittance, and SRI are defined per CRRC and ASTM E1980.
Limitations
This is a non-exhaustive snapshot, not a legal compliance opinion. Additional local jurisdictions maintain cool roof provisions that are not individually listed here, and codes change: adoption dates, climate-zone assignments, and threshold values are periodically revised, so a given city may have amended its rule after July 2026. Many mandates include exemptions (green roofs, high-rise buildings, rooftop equipment, historic structures) and offer a performance-based compliance alternative that can permit a non-reflective roof when whole-building energy targets are met. Requirements vary by roof slope, climate zone, building type, and whether the work is new construction or re-roofing. Building owners and contractors should confirm the current requirement with the local authority having jurisdiction before specifying a roof.
Frequently asked questions
Which US cities require cool or reflective roofs?
As of 2026, cool roof mandates are in force in New York City, Chicago, Philadelphia, Los Angeles, and Denver, plus statewide in California under Title 24. Most rules apply to low-slope commercial and multifamily roofs. Many other cities enforce reflectance indirectly by adopting ASHRAE 90.1 or the IECC, which require cool roofs on low-slope commercial buildings in the hottest climate zones.
What solar reflectance does a cool roof code require?
For low-slope roofs, tracked mandates require an initial solar reflectance between about 0.65 and 0.72 (Philadelphia 0.65, New York City 0.70, Chicago 0.72) or an aged reflectance around 0.55 to 0.63 (ASHRAE 90.1 at 0.55, California Title 24 at 0.63). Steep-slope thresholds are lower, typically an aged reflectance of 0.20 to 0.25, per each jurisdiction’s code and the CRRC (2026).
Does California require a cool roof when I replace my roof?
In many cases, yes. California’s Title 24 covers “alterations including roof recoverings,” so re-roofing an existing home in a covered climate zone (zones 2, 4, and 6-15 for low-slope; 10-15 for steep-slope) may require a CRRC-rated cool product meeting the aged reflectance or SRI minimum. Prescriptive exemptions and a performance-compliance alternative exist, so confirm with your local building department.
Do dark shingles violate cool roof codes?
They can, on a roof the code covers. Dark shingles absorb more sunlight and typically fall below the required reflectance or SRI. Where a mandate applies to steep-slope residential roofs (parts of California, for example), a standard dark asphalt shingle may not comply unless it carries a rated reflective granule coating or the project uses the performance-compliance path.
What is the difference between solar reflectance and SRI?
Solar reflectance is the raw fraction of sunlight a surface reflects, from 0 to 1. The Solar Reflectance Index (SRI), defined by ASTM E1980, combines reflectance and thermal emittance into a single 0-to-100+ scale to estimate relative surface temperature. Codes often let a product comply through either a reflectance-and-emittance pair or an SRI value.
Why do cool roof mandates concentrate in hot cities?
Reflective roofs cut summer heat gain and rooftop surface temperature, which lowers cooling energy use and eases the urban heat island effect. In cold climates a reflective roof can slightly raise winter heating demand, so codes there rarely require it. That heating-versus-cooling tradeoff is why mandates cluster in southern states and dense, paved urban cores.
Reviewed by The Roofing Brief Team. Last reviewed July 2026.