Cool roofing is defined differently by various performance criteria in codes, standards, and incentive programs.  In general, a cool roof is one that has relatively high solar reflectance and high thermal emittance.

SolarReflectiveGraphic-new-1

During the daylight hours, a roof is constantly subjected to solar energy striking its surface.  The term “Solar Reflectance” is a measure of the amount of that solar energy that is immediately reflected from the surface. It is not reflected heat, but reflected electromagnetic energy from the sun.  Solar reflectance is reported as a decimal (0 – 1.00) or as a percentage (0-100%).  The solar energy that is not reflected away from the surface is absorbed into the outer surface of the roof product and is converted into heat. The heat can be removed by convection as air flows over the surface, or by conduction through the roof material into the sheathing below. The energy that is left can also be re-emitted to the night sky in the form of infrared energy. That re-emitted energy is referred to as thermal emittance, which is also expressed as a decimal (0 – 1.00) or as a percentage (0-100%).

Cool Metal Roofing

A cool metal roof with high solar reflectance and high thermal emittance would have a lower surface temperature as compared to a roof with low reflectance and low emittance. In the case of a cool metal roof, a lower surface temperature translates into less heat gain into the attic space or living space below the roof.  The result is a cooler living space and lowercooling/heating energy consumption.

Studies have shown that a cool metal roof can save a building owner as much as 20% in their cooling energy costs.  In addition, by reducing energy production at the power plants, greenhouse gases that are emitted in the production process are thereby reduced.  Many metal roofing systems are Energy Star labeled and meet other cool roof requirements in codes and standards.

Energy Star Roofing

EPA’s Energy Star® program is familiar to many homeowners who see the label on appliances and electronic equipment. Energy Star also has a Roof Products component for cool roofing.  A roof that meets the Energy Star performance requirements is considered one that is cool and helps to reduce urban heat island effects.  The criteria for an Energy Star labeled roof are:

  • For steep slope applications (greater than 2:12 pitch):  initial minimum solar reflectance of 0.25, and 3-year aged minimum solar reflectance of 0.15.
  • For low slope applications (2:12 or less pitch):  initial minimum solar reflectance of 0.65 and 3-year aged minimum solar reflectance of 0.50. 
Solar Reflectance, Thermal Emittance, and SRI Values for Kynar 500 Colors
COLOR REFLECTANCE EMISSIVITY SRI
Almond - PVDF .60 .84 70
Ash Gray - PVDF .39 .84 41
Autumn Red - PVDF .31 .85 35
Bone White - PVDF .71 .85 86
Brandywine - PVDF .26 .85 24
Brite Red - PVDF .42 .84 45
Buckskin - PVDF .38 .86 41
Champagne Metallic - PVDF .38 .80 38
Charcoal - PVDF .32 .85 32
Clay - PVDF .32 .86 33
Colonial Red - PVDF .33 .85 34
Copper Penny Metallic - PVDF .49 .85 55
Dark Bronze - PVDF .26 .84 24
Evergreen - PVDF .26 .84 24
Galvalume Plus  .69 .19 62
Hartford Green - PVDF .25 .85 23
Ivory - PVDF .67 .87 81
Leadcoat - PVDF .37 .82 38
Light Stone - PVDF .53 .86 61
Mansard Brown - PVDF .30 .85 30
Matte Black - PVDF .27 .86 26
Medium Bronze - PVDF .30 .87 31
Patina Green - PVDF .46 .85 51
Patrician Bronze - PVDF .27 .86 26
Preweathered Galvalume - PVDF .30 .79 27
Regal Blue - PVDF .26 .85 24
Regal White - PVDF .68 .86 82
Roman Blue - PVDF .26 .85 24
Sandstone - PVDF .54 .86 63
Silver Metallic - PVDF .57 .78 64
Slate Gray - PVDF .43 .85 47
Surrey Beige - PVDF .40 .86 43
Terra Cotta - PVDF .35 .85 36
Terratone - PVDF .33 .86 34
Texas Silver Metallic - PVDF .58 .78 66
Tudor Brown - PVDF .29 .86 29
Solar Reflectence, Thermal Emittance, and SRI Values for Silicone Modified Polyester (SMP) Colors
COLOR REFLECTANCE EMISSIVITY SRI
Alamo White .64 .86 77
Antique Brown .28 .86 27
Ash Gray .46 .86 52
Autumn Red .35 .86 37
Brandywine .33 .87 35
Brite White - Galv Substrate .62 .87 74
Brite White - Galvalume Substrate .66 .87 80
Charcoal .37 .86 39
Clay .42 .86 46
Evergreen .29 .86 29
Ivory - Galv Substrate .65 .87 78
Ivory - Galvalume Substrate .69 .87 84
Light Stone .56 .86 65
Mansard Brown .68 .86 82
Matte Black .31 .86 31
Patrician Bronze .30 .87 31
Pewter Gray .46 .86 52
Roman Blue .32 .86 33
Surrey Beige .46 .87 52
Terratone .31 .86 31
Timber Tan .47 .86 53
Tudor Brown .33 .86 34
 
MET-TILE COLOR REFLECTANCE EMISSIVITY SRI
Bravo Red .46 .86 52
Cotillion White .67 .86 81
Coral Blue .27 .87 27
Gallery Blue .30 .85 30
Meadow Green .28 .85 27
Mission Clay .36 .87 39
Morocco Red .27 .86 39
Ranchwood Brown .29 .83 27
Slate Gray .26 .85 24
Spanish Tile Red .35 .86 37

 

Homeowners who added "cool" metal roofs to their primary residence in 2016 are eligible for the $500 tax credit. Homeowners who chose a metal roof in 2015 can also take advantage of the tax break.

How to receive the tax credit:

1.  Confirm that the metal roof you select is a painted or coated Energy Star-labeled metal roof and obtain certification from your contractor or McElroy Metal. Verify the metal roof was installed between January 1, 2015 and December 31, 2016.

2.  Fill out IRS Form 5695 when filing your taxes for 2015 and/or 2016.

For more information on what qualifies for the Tax Credit go to the Energy Star web page on qualified metal roofs or review the IRS guidance on qualifying energy-efficient property.

Colors that meet Energy Star requirements for Cool Roofing