Significance and Use Heat buildup in PVC exterior building
products due to absorption of the energy from the sun may lead
to distortion problems. Heat buildup is affected by the color,
emittance, absorptance, and reflectance of a product. Generally,
the darker the color of the product, the more energy is absorbed
and the greater is the heat buildup. However, even with the same
apparent color, the heat buildup may vary due to the specific
pigment system involved. The greatest heat buildup generally
occurs in the color black containing carbon black pigment. The
black control sample used in this test method contains 2.5 parts
of furnace black per 100 parts of PVC suspension resin. The
maximum temperature rise above ambient temperature for this
black is 90°F (50°C) for a 45° or horizontal surface when the
sun is perpendicular to the surface and 74°F (41°C) for a
vertical surface assuming that the measurements were done on a
cloudless day with no wind and heavy insulation on the back of
the specimen. See Appendix