Passive Purple solar-reflective performance — SRI 52

Passive Purple: Solar-Reflective Performance in a Coloured Coating (SRI 52)

Most high-solar-performance coatings are white. Passive Purple breaks that convention — the standard purple coating reflects nearly half of all incoming solar energy, with an independently calculated Solar Reflectance Index (SRI) of 52.

Passive Purple solar-reflective airtight coating

SRI 52 — independently calculated

R&D Services, Inc. — an ISO/IEC 17025 accredited laboratory — calculated Passive Purple’s SRI to ASTM E1980-11 (Report No. RD23548, May 2023):

  • Solar reflectance 0.453 — reflects around 45% of incoming solar energy
  • Thermal emittance 0.907 — radiates absorbed heat so the surface stays cooler
  • SRI 52 — comfortably exceeds the LEED steep-slope cool-roof threshold (SRI ≥ 39)

(For reference, the separate Passive Purple External grade is a different formulation and colour, and is not the SRI 52 product.)

Tested and certified across the board

Passive Purple is one of the most thoroughly tested liquid airtight coatings on the market. It holds ICC-ES Evaluation Report ESR-4715, confirming compliance with the 2021, 2018 and 2015 International Building Code, International Residential Code and International Energy Conservation Code (with a City of Los Angeles supplement):

  • Air barrier — ASTM E2178: air leakage of just 0.02 L/s·m² at 75 Pa at 20 mils, qualifying Passive Purple and Passive Purple Brush as air barrier materials.
  • Surface burning — ASTM E84: Flame Spread Index 0 (Smoke Developed 55; Passive Purple Brush 0 / 35) — a Class A result.
  • Solar reflectance — ASTM E1980: SRI 52.
  • Also independently tested: fungus resistance (ASTM G21) and reaction to heat (ASTM E1354).

Why a reflective coating matters

Dark surfaces absorb solar energy, driving up surface temperatures, internal overheating and cooling demand. A coating that reflects ~45% of solar energy and radiates heat away keeps surfaces cooler — a growing concern under Approved Document O, which addresses overheating in new homes. With Passive Purple you get that reflectance alongside a certified airtight, vapour control and Class A fire performance in a single coating.

Performance and colour, together

High solar performance has traditionally meant a white finish. Passive Purple delivers measured solar reflectance in its signature colour — no compromise on aesthetics.

Explore Passive Purple, or contact us for the full test reports and specification support.

Independently tested, third-party certified — no marketing claims without the data to back them up.

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