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INDUSTRY REPORTS · July 25, 2026

Roofing Solar Reflectance Index (SRI) Table and Reference (2026): Measured Values by Roof Type and Color

Solar reflectance index table for roofing: SRI, reflectance and emittance by roof type and color, plus Title 24, IECC and LEED aged SRI minimums.

By The Roofing Brief Team

By The Roofing Brief Team. Last reviewed: October 2026.

A solar reflectance index table for roofing starts from two ASTM E1980 anchors: a reference black roof (solar reflectance 0.05, thermal emittance 0.90) scores SRI 0 and a reference white roof (0.80, 0.90) scores SRI 100. Measured surfaces run from SRI 6 for a standard red tile to 107 for a clean bright-white membrane, and about 98% of products in the CRRC Rated Roof Products Directory stay between 0 and 100 after three years of weathering, per the CRRC SRI explainer (April 2024). Every number below traces to the CRRC, the LBNL Heat Island Group, the ASTM E1980 standard, the U.S. DOE, Guidelines for Selecting Cool Roofs, July 2010, or the code text that sets the thresholds.

Three properties define how hot a roof gets in the sun. Solar reflectance is the fraction of sunlight a surface reflects rather than absorbs, on a 0 to 1 scale. Thermal emittance is how efficiently the surface re-radiates absorbed heat, also 0 to 1. SRI combines both into a single index where a standard black surface is 0 and a standard white surface is 100 (LBNL Heat Island Group, 2009; ASTM E1980-11 (2019)).

Which SRI does your roof need? Decision table

Codes and green-building programs set different SRI floors, and most of them test the 3-year aged value rather than the initial one. Find your program, then compare a product’s aged values in its CRRC listing against the threshold.

If your roof must meet Slope Minimum (aged unless noted) Surfaces from this table that pass Source
California Title 24, nonresidential new roof or reroof, or single-family reroof in climate zones 4 and 6 to 15 Low slope Solar reflectance 0.63 and emittance 0.75, or SRI 75 Bright white membrane (aged SRI 79); aged zincalume (26) fails CRRC chart of the 2025 Title 24 code (Dec 4, 2025; same values as the 2022 code), Sections 140.3(a)1Aia, 141.0(b)2Bi, 150.2(b)1Iii
California Title 24, single-family reroof in climate zones 4 and 8 to 15 Steep slope Solar reflectance 0.20 and emittance 0.75, or SRI 16 Cool color shingle (about SRI 25), cool tile (38); standard dark tile or shingle (about 7) fails CRRC 2025 Title 24 chart, Section 150.2(b)1Ii
IECC commercial roof in climate zones 0 to 3 Low slope Solar reflectance 0.55 and emittance 0.75, or SRI 64 Bright white membrane (aged 79); standard gray (19) fails IECC roof reflectance section (C402.3 in 2021, C402.4 in 2024)
LEED v4 or v4.1 Heat Island Reduction Low slope, 2:12 or less Initial SRI 82, or aged SRI 64 Bright white membrane (initial 107, aged 79) USGBC LEED v4 Heat Island Reduction credit
LEED v4 or v4.1 Heat Island Reduction Steep slope, over 2:12 Initial SRI 39, or aged SRI 32 White metal (about 85), white tile (80), white shingle (71); cool color tile (38) misses the initial 39 USGBC LEED v4
U.S. DOE steep-slope cool roof definition Steep slope Aged SRI 29 White shingle, tile and metal; cool color shingle (about 25) falls short U.S. DOE, 2010
Any program, with bare or unpainted metal Either Check emittance first: bare zincalume emits 0.05 to 0.20 Painted or coated metal; bare metal usually fails the 0.75 emittance floor LBNL, 2009; U.S. DOE, 2010

Executive Summary

This reference sets solar reflectance, thermal emittance, and SRI for common United States roofing surfaces against their primary sources. The headline points below trace to ASTM E1980, LBNL, the U.S. DOE, and the CRRC, and show how color, material, and emittance move a roof from an SRI of 0 to 107 (LBNL, 2009; CRRC, 2024).

  • By ASTM E1980 convention, a reference black roof (solar reflectance 0.05, thermal emittance 0.90) has an SRI of 0, and a reference white roof (solar reflectance 0.80, thermal emittance 0.90) has an SRI of 100 (LBNL Heat Island Group, 2009).
  • Most dark roof materials reflect 5 to 20 percent of sunlight, while light-colored roof materials typically reflect 55 to 90 percent (U.S. DOE, Guidelines for Selecting Cool Roofs, 2010).
  • A clean bright-white low-slope surface (reflectance 0.85, emittance 0.90) reaches an initial SRI of 107 and sits only about 9 degrees F above outside air on a summer afternoon; a standard gray roof (reflectance 0.20) reaches SRI 19 and sits about 69 degrees F above air (LBNL, 2009).
  • Thermal emittance matters independently of color: bare zincalume steel reflects about 75 percent of sunlight but emits at only 0.05, giving it an SRI of 68, lower than a white membrane of similar reflectance (LBNL, 2009).
  • The CRRC Rated Products Directory holds more than 3,000 rated products with initial and three-year-aged solar reflectance, thermal emittance, and SRI, measured by accredited independent labs (CRRC, 2024).
  • The ENERGY STAR roof-products program, whose thresholds are still widely cited in specifications, was retired in June 2022; the CRRC directory is now the primary U.S. radiative-property database (CRRC, 2024).
  • Weathering lowers reflectance: a CRRC sample label shows solar reflectance dropping from 0.87 initial to 0.77 after three years, with thermal emittance nearly unchanged (U.S. DOE, 2010).
  • Cool dark colors exist: a cool dark tile can reflect about 0.40 versus about 0.04 to 0.20 for a conventional dark surface, an increase of roughly 0.4 in reflectance from near-infrared reflective pigments (LBNL, 2009; U.S. DOE, 2010).

Key Findings

The numbered findings below list every measured and standards-defined value in this reference, each attributed inline to its primary source. They run from the ASTM E1980 reference surfaces through white membranes, bare metal, cool dark colors, and the cool-roof thresholds set by the California Energy Commission, LEED, the U.S. DOE, and the retired ENERGY STAR program (LBNL, 2009; U.S. DOE, 2010).

  1. Reference black roof: solar reflectance 0.05, thermal emittance 0.90, SRI 0. Reference white roof: solar reflectance 0.80, thermal emittance 0.90, SRI 100 (United States, ASTM E1980 convention; LBNL Heat Island Group, 2009).
  2. Bright white low-slope surface, initial: reflectance 0.85, emittance 0.90, SRI 107, surface about 9 degrees F (5 K) above outside air on a summer afternoon (LBNL, 2009).
  3. Standard gray roof: reflectance 0.20, emittance 0.90, SRI 19, surface about 69 degrees F (38 K) above outside air (LBNL, 2009).
  4. Cool red tile: reflectance 0.35, emittance 0.90, SRI 38, surface about 56 degrees F (31 K) above air. Standard red tile: reflectance 0.10, emittance 0.90, SRI 6, about 78 degrees F (44 K) above air (LBNL, 2009).
  5. Bare zincalume steel: reflectance 0.75, emittance 0.05, SRI 68, about 36 degrees F (20 K) above air; the low emittance keeps it warmer than a white roof despite high reflectance (LBNL, 2009).
  6. Three-year weathering drops the bright-white low-slope surface to reflectance 0.65 and SRI 79, and drops bare zincalume to reflectance 0.50, emittance 0.20, SRI 26; a standard gray roof shows no net change (LBNL, 2009).
  7. White single-ply membranes carry high initial values: one CRRC and former ENERGY STAR listed white TPO reports initial solar reflectance 0.79 and emittance 0.90; a white PVC membrane range is about 0.80 to 0.87 reflectance (manufacturer CRRC datasheets, 2024).
  8. Steep-slope initial values (read from LBNL charts): white metal near SRI 85, white tile near SRI 80, white shingle near SRI 71, cool color tile and cool color metal near SRI 38, cool color shingle near SRI 25 (LBNL, 2009). For maker-rated values, see our list of the SRI of 21 white metal roof colors by maker.
  9. Most dark roofs absorb 90 percent or more of incoming solar energy and can exceed 150 degrees F (66 degrees C) in summer sun; a cool roof under the same conditions can stay more than 50 degrees F (28 degrees C) cooler (U.S. DOE, 2010).
  10. California Title 24 minimum cool-roof values (three-year aged) under the 2025 code, in effect since January 1, 2026, and unchanged from the 2022 code: low-slope solar reflectance 0.63 and emittance 0.75, or SRI 75, for nonresidential roofs and single-family reroofs in climate zones 4 and 6 to 15; steep-slope reflectance 0.20 and emittance 0.75, or SRI 16. The low-slope 0.55 and SRI 64 values in DOE’s 2010 guide come from an earlier code cycle and now apply in California only to hotel and motel guest-room roofs (CRRC chart of the 2025 Title 24 code, Dec 4, 2025). CRRC lists the 2025 code’s changes, effective January 1, 2026, as SRI-calculation and multifamily updates.
  11. LEED-NC 2009 used minimum SRI values of 78 for low-slope and 29 for steep-slope roofs; LEED v4 and v4.1 raised them to initial SRI 82 or aged SRI 64 for roofs at 2:12 or less, and initial SRI 39 or aged SRI 32 above 2:12 (USGBC). The DOE defines a steep-slope cool roof as three-year aged SRI of 29 or greater (U.S. DOE, 2010).
  12. Retired ENERGY STAR roof thresholds, still referenced in specs: low-slope solar reflectance 0.65 initial and 0.50 aged; steep-slope 0.25 initial and 0.15 aged; the program did not consider thermal emittance (U.S. DOE, 2010; CRRC, 2024).
  13. SRI 78 can be reached with reflectance 0.77 and emittance 0.20, or with reflectance 0.64 and emittance 0.90; SRI 29 can be reached with reflectance 0.28 and emittance 0.90 (U.S. DOE, 2010).
  14. Cool-colored tile measurements: black 0.41 cool versus 0.04 conventional; blue 0.44 versus 0.18; grey 0.44 versus 0.21; terracotta 0.48 versus 0.33; green 0.46 versus 0.17; chocolate 0.41 versus 0.12 (American Rooftile Coatings and LBNL, in U.S. DOE, 2010).
  15. CRRC-rated Alunar-coated aluminum colors, initial solar reflectance and SRI: Aged Copper 0.44 and SRI 49; Tile Red 0.32 and SRI 31; Royal Blue 0.25 and SRI 22; Black 0.25 and SRI 22 (manufacturer CRRC listing, 2024).
  16. SRI is calculated per ASTM E1980-11 (2019) using medium wind speed, with solar reflectance measured by ASTM C1549 or E903 and thermal emittance by ASTM C1371 or E408 (ASTM International; CRRC, 2024).

How the Three Properties Relate

Solar reflectance does most of the work in keeping a roof cool, but emittance sets the floor. LBNL frames the difference with worked reference surfaces. A bright white roof at reflectance 0.85 and emittance 0.90 reaches SRI 107 and sits only 9 degrees F above air temperature. A bare zincalume steel roof reflects nearly as much sunlight, 0.75, but because it emits at only 0.05 it reaches SRI 68 and runs 36 degrees F above air (LBNL, 2009). Two surfaces that reflect similar amounts of sunlight can therefore differ by roughly 40 SRI points based on emittance alone.

Color is not destiny. Per the LBNL Heat Island Group, standard light-colored surfaces reflect strongly in both the visible and near-infrared bands, while conventional dark surfaces reflect little in either. Special pigments that reflect near-infrared sunlight produce cool dark colors whose solar reflectance can exceed that of a conventional dark color by about 0.4 (LBNL, 2009). This is why a cool-colored asphalt shingle or tile can carry a meaningfully higher SRI than a visually identical standard product. For a plain-language walkthrough of this effect on shingles, see our guide to solar reflective shingles.

Reference Table: Standards-Defined and Measured Values by Surface

This table pairs each surface with its solar reflectance, thermal emittance, and SRI from ASTM E1980 and LBNL. A reference black roof scores SRI 0 and a reference white roof SRI 100, while a bright white low-slope surface reaches an initial SRI of 107 and bare zincalume steel only 68 despite reflecting 0.75 of sunlight, because it emits heat poorly (LBNL, 2009).

Surface (condition) Solar reflectance Thermal emittance SRI Source
Reference black 0.05 0.90 0 ASTM E1980 / LBNL 2009
Reference white 0.80 0.90 100 ASTM E1980 / LBNL 2009
Bright white low-slope (initial) 0.85 0.90 107 LBNL 2009
Bright white low-slope (3-yr aged) 0.65 0.90 79 LBNL 2009
Standard gray roof 0.20 0.90 19 LBNL 2009
Cool red tile 0.35 0.90 38 LBNL 2009
Standard red tile 0.10 0.90 6 LBNL 2009
Bare zincalume steel (initial) 0.75 0.05 68 LBNL 2009
Bare zincalume steel (3-yr aged) 0.50 0.20 26 LBNL 2009

Values with a condition noted as initial or aged reflect measured change over three years of natural exposure. SRI figures use ASTM E1980 at medium wind speed.

Steep-Slope Products: Approximate Initial Values by Type

Steep-slope residential products span a wide SRI range by color and material. Read from LBNL initial-property charts, white metal sits near SRI 85, white tile near 80, and white shingle near 71, while cool color tile and cool color metal reach about 38 and standard dark colors fall near SRI 7 (LBNL, 2009). Treat these chart-read figures as approximate rather than single manufacturer ratings.

Product Approx. solar reflectance Approx. SRI
White metal 0.70 85
White tile 0.65 80
White shingle 0.60 71
Cool color tile 0.35 38
Cool color metal 0.35 38
Cool color shingle 0.25 25
Standard color tile or shingle 0.10 7

Source: LBNL Heat Island Group, Cool Roof Q and A, 2009, Figure 2. Read from chart, so treat as approximate rather than a single manufacturer rating.

Single-Ply Membranes and Coatings

White single-ply membranes are among the highest-reflectance factory surfaces available for low-slope roofs. A white TPO membrane listed by CRRC and formerly by ENERGY STAR reports initial solar reflectance of 0.79 and thermal emittance of 0.90, and white PVC membranes fall in a similar 0.80 to 0.87 reflectance range (manufacturer CRRC datasheets, 2024). White field-applied elastomeric coatings and white modified bitumen sit near the top of the low-slope SRI chart, close to the reference white anchor (LBNL, 2009). EPDM membranes are typically black and must be formulated or coated to reflect well (U.S. DOE, 2010). Our comparison of TPO roofing colors covers the reflectance tradeoff between standard white and darker premium TPO.

Metal Roofing Colors

Painted metal spans a wide SRI band by color. CRRC-rated Alunar-coated aluminum values illustrate the range: Aged Copper at solar reflectance 0.44 and SRI 49, Tile Red at 0.32 and SRI 31, and darker colors such as Black clustered near reflectance 0.25 and SRI 22 (manufacturer CRRC listing, 2024). A separate manufacturer color set using an aluminum-zinc coating reports values such as Polar White at 0.68 initial reflectance, Almond at 0.63, Slate Grey at 0.37, Colonial Red at 0.34, and Black at 0.25 (manufacturer data, treated as Tier 3). Unpainted metal is usually a good reflector but a poor emitter, so it rarely meets low-slope cool-roof requirements even when reflectance is high (U.S. DOE, 2010). Maker-rated values by color are compiled in our guide to the solar reflectance of red metal roof colors and in our list of the SRI of 62 gray metal roof finishes.

Cool Roof Thresholds by Standard

Cool-roof programs set different bars, which is a frequent source of confusion in specifications. California’s current Title 24 accepts a three-year aged SRI of 75 for low-slope and 16 for steep-slope roofs, the IECC accepts aged SRI 64 for low-slope commercial roofs in climate zones 0 to 3, LEED v4 uses initial SRI 82 or aged 64 (low slope) and 39 or 32 (steep slope), and the retired ENERGY STAR program used reflectance 0.65 initial for low-slope while ignoring emittance (CRRC 2025 Title 24 chart; USGBC; U.S. DOE, 2010). The table consolidates the verified thresholds, with older values labeled.

Standard Low-slope requirement Steep-slope requirement
California Title 24, 2025 code, same as 2022 (3-yr aged) Reflectance 0.63 and emittance 0.75, or SRI 75 (nonresidential; single-family reroof in CZ 4, 6 to 15) Reflectance 0.20 and emittance 0.75, or SRI 16 (single-family reroof in CZ 4, 8 to 15)
California, older cycle cited by DOE 2010 (3-yr aged) Reflectance 0.55 and emittance 0.75, or SRI 64 Reflectance 0.20 and emittance 0.75, or SRI 16
IECC commercial, climate zones 0 to 3 (3-yr aged) Reflectance 0.55 and emittance 0.75, or SRI 64 No requirement
LEED v4 / v4.1 (SRI) Initial 82 or aged 64 (2:12 or less) Initial 39 or aged 32 (over 2:12)
LEED-NC 2009 (SRI) SRI 78 SRI 29
U.S. DOE (aged SRI) Uses CEC low-slope definition SRI 29 or greater
ENERGY STAR (retired June 2022) Reflectance 0.65 initial, 0.50 aged Reflectance 0.25 initial, 0.15 aged

Sources: U.S. DOE, Guidelines for Selecting Cool Roofs, July 2010; CRRC chart of 2025 Title 24 cool roof requirements, Dec 4, 2025; CRRC 2022 Title 24 summary; USGBC LEED v4 Heat Island Reduction credit; IECC roof reflectance section; CRRC, 2024. ENERGY STAR thresholds are retained here because they still appear in older specifications, not because the program is active.

Title 24, the IECC and city ordinances turn these SRI thresholds into legal requirements; for where that applies, see our cool roof mandates by city report, and for the energy side of the equation see our cool roof energy savings report.

Roofing Brief Calculations (Original Synthesis)

The following figures are derived by The Roofing Brief from the primary datasets above. They are calculations, not published statistics. Inputs and limitations are stated for each.

1. The emittance penalty at equal SRI

Roofing Brief calculation: to reach SRI 78, a low-emittance surface (emittance 0.20) needs solar reflectance 0.77, while a high-emittance surface (emittance 0.90) needs only 0.64. The low-emittance surface must reflect 0.13 more sunlight, about 20 percent more in relative terms, to land at the same SRI. Inputs: U.S. DOE (2010) worked SRI targets. Limitation: based on two anchor points at a single SRI value, not a full regression across the reflectance range.

2. Three-year SRI retention by surface

Roofing Brief calculation: dividing aged SRI by initial SRI gives a retention rate. The bright-white low-slope surface retains 79 of 107, or about 74 percent. Bare zincalume steel retains 26 of 68, or about 38 percent. A standard gray roof retains 100 percent because it does not change. Bare metal surfaces lose the most index value to weathering, roughly double the loss of a white membrane. Inputs: LBNL (2009) initial and aged reference values. Limitation: three reference surfaces, not a product-wide average; real products vary by pigment, substrate, and climate.

3. Steep-slope compliance gap between standards

Roofing Brief calculation: LEED-NC 2009 and DOE both set a steep-slope floor of SRI 29, about 81 percent higher than the California Energy Commission steep-slope alternative of SRI 16. A cool-colored shingle near SRI 25 clears the California SRI 16 floor but falls 4 points short of the SRI 29 LEED and DOE floor. Inputs: U.S. DOE (2010) threshold table; LBNL (2009) cool color shingle value. Limitation: the SRI 25 shingle value is read from a chart and approximate; individual products should be checked against their own CRRC listing.

4. Reflectance-to-temperature slope

Roofing Brief calculation: across four LBNL reference surfaces at emittance near 0.90, surface-temperature elevation falls from about 78 degrees F at reflectance 0.10 to about 9 degrees F at reflectance 0.85. That is roughly a 9 degrees F reduction in surface-temperature elevation for every 0.10 gain in solar reflectance. Inputs: LBNL (2009) reference surfaces (reflectance and delta-T pairs of 0.10 and 78, 0.20 and 69, 0.35 and 56, 0.85 and 9). Limitation: emittance held near 0.90, a single reference afternoon and climate, and a straight-line fit to a relationship that is not perfectly linear.

Recommended Charts

  • SRI versus solar reflectance scatter by product type. Data: LBNL initial and aged values, from SRI 6 (standard red tile) to 107 (bright white). Insight: emittance separates bare metal from white membranes at equal reflectance. Citation-worthy because it visualizes why reflectance alone does not determine SRI.
  • Three-year SRI retention bar chart by surface. Data: LBNL initial and aged SRI. Insight: bare zincalume keeps 38% of its SRI (68 to 26) versus 74% for bright white (107 to 79). Useful for lifecycle and warranty discussions.
  • Standard-by-standard threshold comparison. Data: DOE threshold table. Insight: the same shingle can pass one program and fail another. Useful for specifiers and code officials.
  • Cool versus conventional color reflectance pairs. Data: cool-colored tile measurements. Insight: near-infrared pigments raise reflectance by roughly 0.2 to 0.4 without changing visible color.

Methodology

Sources were selected in this order: national standards bodies and government or national-laboratory publications first, then the industry rating council that maintains the U.S. product database, then manufacturer datasheets that report values measured under the CRRC program. Every reflectance, emittance, and SRI figure was taken from a source fetched during this research and is attributed inline. Where a figure was read from a chart rather than a numeric table, it is labeled approximate. Conflicting numbers were handled by preferring the primary measurement source and by reporting ranges where the literature reports ranges. Derived figures are labeled as Roofing Brief calculations with their inputs and limitations. No figure was included that could not be traced to a fetched source. Last updated October 19, 2026, when the current Title 24, IECC and LEED v4 thresholds were added and the outdated California low-slope values were relabeled.

Source Quality Ranking

Tier 1 (primary standards, government, national laboratory): ASTM E1980-11 (2019); U.S. Department of Energy, Guidelines for Selecting Cool Roofs, July 2010; LBNL Heat Island Group, Cool Roof Q and A, July 2009, and the coolscience cool-roofs page.

Tier 2 (industry rating body and manufacturer CRRC data): Cool Roof Rating Council Rated Products Directory and SRI documentation, 2024; manufacturer CRRC datasheets for TPO, PVC, and coated aluminum products.

Tier 3 (manufacturer marketing data, used with caution): aluminum-zinc coated metal color reflectance tables where methodology is stated as ASTM E1980 but values are self-reported.

Excluded: unsourced roundup pages, AI-generated summaries, and any single figure that could not be matched to a fetched primary or manufacturer source.

Most Quotable Statistics

  • A reference white roof scores SRI 100 and a reference black roof scores SRI 0, by ASTM E1980 convention (LBNL, 2009).
  • Most dark roofs absorb 90 percent or more of incoming sunlight and can exceed 150 degrees F in summer; a cool roof can stay more than 50 degrees F cooler (U.S. DOE, 2010).
  • Two roofs that reflect about 0.75 of sunlight can differ by roughly 40 SRI points based on emittance alone (LBNL, 2009).
  • The CRRC directory lists more than 3,000 rated roof products, and became the primary U.S. radiative-property database after ENERGY STAR retired its roof program in June 2022 (CRRC, 2024).

Data Limitations

Several core reference values date to LBNL and DOE publications from 2009 and 2010; the physics and the ASTM convention are unchanged, but individual product ratings should be checked against the current CRRC directory. Some steep-slope figures were read from charts and are approximate. Manufacturer color values are self-reported under the CRRC test method and can vary by production run and substrate. Aged values assume roughly three years of natural exposure and vary with climate, soiling, and cleaning. The retired ENERGY STAR thresholds are included for reference only.

Downloadable Dataset: Recommended Fields

A reusable version of this reference should carry these fields per record: product or surface name; material class; color; slope class (low or steep); initial solar reflectance; aged solar reflectance; initial thermal emittance; aged thermal emittance; initial SRI; aged SRI; test method (ASTM E1980 wind speed); rating body; source citation; and last-verified date.

Press Summary

Roofing surfaces vary enormously in how much heat they shed, and the industry measures that with three numbers: solar reflectance, thermal emittance, and the combined Solar Reflectance Index. Under the ASTM E1980 convention, a reference black roof scores 0 and a reference white roof scores 100. Measured values from the Lawrence Berkeley National Laboratory show a bright white membrane reaching an initial SRI of 107 and sitting just 9 degrees F above air temperature, while a standard gray roof reaches only 19 and runs 69 degrees F hotter. Emittance matters as much as color: bare metal that reflects 75 percent of sunlight still scores well below a white membrane because it re-radiates heat poorly. The Cool Roof Rating Council now maintains the primary U.S. database of more than 3,000 rated products after the ENERGY STAR roof program was retired in June 2022. This reference consolidates the verified values by roof type and color.

Suggested Headlines

  • The Roofing Reflectance Numbers, by Type: What Actually Scores Cool in 2026
  • Why a White Roof Beats Shiny Metal Even at the Same Reflectance
  • SRI 0 to 107: The Full Range of U.S. Roofing Surfaces, Explained
  • After ENERGY STAR: Where Roof Reflectance Data Lives Now
  • Cool Dark Colors Are Real, and the Reflectance Data Proves It

Frequently Asked Questions

What is solar reflectance for a roof?

Solar reflectance is the fraction of sunlight a roof surface reflects rather than absorbs, on a 0 to 1 scale. Most dark roof materials reflect 5 to 20 percent, and light-colored materials typically reflect 55 to 90 percent (U.S. DOE, 2010).

What is thermal emittance?

Thermal emittance is how efficiently a surface re-radiates absorbed heat, on a 0 to 1 scale, measured by ASTM C1371 or E408. Most nonmetallic roofing surfaces emit between 0.80 and 0.95, while bare shiny metals emit much less, such as 0.05 for new zincalume (U.S. DOE, 2010; LBNL, 2009).

What is SRI and how is it calculated?

SRI, the Solar Reflectance Index, combines solar reflectance and thermal emittance into one value using ASTM E1980 at medium wind speed. A reference black roof is 0 and a reference white roof is 100 (ASTM International; LBNL, 2009).

Can SRI be above 100 or below 0?

Yes. Under ASTM E1980, a clean bright-white surface can reach an initial SRI of 107, and surfaces hotter than the reference black can fall below 0; about 98% of CRRC-rated products stay between 0 and 100 after three years (LBNL, 2009; CRRC, 2024).

What is the SRI of a white membrane versus bare metal?

A bright white low-slope surface (reflectance 0.85, emittance 0.90) reaches an initial SRI near 107, while bare zincalume steel that reflects almost as much sunlight reaches only 68 because it emits heat poorly (LBNL, 2009).

What solar reflectance do asphalt shingles have?

Standard dark shingles fall in the low reflectance band with the broader dark-material range of 5 to 20 percent, white shingles reach an SRI near 71, and cool color shingles reach an SRI near 25 in LBNL charts (U.S. DOE, 2010; LBNL, 2009).

What counts as a cool roof?

It depends on the standard. California Title 24 uses a three-year aged SRI of 75 for low-slope and 16 for steep-slope roofs, the IECC uses aged SRI 64 for low-slope commercial roofs in climate zones 0 to 3, and LEED v4 uses initial SRI 82 or aged 64 for low slopes and 39 or 32 for steep slopes (CRRC; USGBC).

What is 3-year aged solar reflectance?

It is the solar reflectance a roof product keeps after three years of outdoor exposure at CRRC test farms, reported next to the initial value on its CRRC label. Codes use the aged number: Title 24 requires an aged reflectance of 0.63 on low-slope and 0.20 on steep-slope roofs, and the IECC 0.55 on low-slope commercial roofs in climate zones 0 to 3 (CRRC 2022 Title 24 summary; IECC).

Are the ENERGY STAR roof thresholds still valid?

The ENERGY STAR roof-products program was retired in June 2022. Its thresholds, low-slope reflectance 0.65 initial and steep-slope 0.25 initial, still appear in older specifications, but current ratings come from the CRRC directory (CRRC, 2024).

How much does reflectance drop as a roof ages?

A bright-white low-slope surface can drop from 0.85 to 0.65 reflectance over three years, lowering its SRI from 107 to 79, a loss of 28 points; most weathering happens in the first year or two (LBNL, 2009; U.S. DOE, 2010).

Do dark colors have to be hot?

No. Near-infrared reflective pigments create cool dark colors whose solar reflectance can exceed a conventional dark color by about 0.4: a cool black tile measured 0.41 versus 0.04 for conventional black, so a cool dark tile can reflect near 0.40 versus about 0.04 to 0.20 for a standard dark surface (LBNL, 2009; U.S. DOE, 2010).

For related context on how roof color drives city and rooftop temperatures, such as the 55 degrees F gap LBNL reports between an 80% reflective white roof and a 20% gray roof, see our report on dark roofs and urban heat, and for whether reflective shingles pay off, see white roof shingles.