Sustainability and LEED v4.1 Metal Roofing & Siding Update
Metal is a naturally green building material with a lifespan of over 50 years and is 100% recyclable at the end of its life use. As the market continues to transform the way sustainable buildings are designed, single skin metal roof and siding continues to contribute to a healthier built environment. This blog breaks down the material inputs and green performance attributes of metal and identifies how metal can contribute to LEED v4.1, making it easier for architects to design green and specify with metal.
Painted metal is made up of several layers of materials. Of all these materials, three ingredients deliver the green performance attributes metal panels are known for. They are the:
- Base Steel
- Aluminum-zinc coating
- Cool Top Coat/Color
The Base Steel is the material that contributes to the long lifespan of the product and is 100% recyclable at the end of its life use.
The Aluminum-Zinc Coating, known as Galvalume® or ZINCALUME® coating, offers outstanding corrosion protection which extend.
The Cool Top Coat/Color is the material that delivers the “cool” roof and siding attribute.
“Cool” Roofing and Siding
Cool Top Coat/Color coatings with solar-reflective attributes are applied to the metal panels delivering the “cool” functionality that helps keeps buildings cooler and drives down energy costs.. How it works is that solar radiation reaches the earth’s surface in three distinct wavelengths; with the infrared radiation generating heat on surfaces. The pigments in our paint systems have been altered with special infrared reflective pigments that stay cooler than traditional pigments. So when the infrared radiation wavelength hits the surface of the metal roof, it allows for solar reflectance and thermal emittance and contributes to keeping the building cool, conserving energy, and saving on energy costs. The images below give a depiction of this.
LEED Green Rating System
The USGBC’s LEED green rating system is the most recognized rating system and a LEED v4.1 assessment is a good foundation in understanding how metal panels can contribute to green building certification programs. Metal panels can contribute points to four credit categories:
- Sustainable Sites
- Energy and Atmosphere
- Materials and Resources
- Indoor Environmental Quality
Cool Metal roofs improve energy performance by reflecting more sunlight and absorbs less heat, keeping the interior spaces cooler. They reduce what is called “Urban Heat Island Effect” (or UHIE) in built-up areas that are hotter than nearby rural areas. This phenomenon occurs because building materials commonly used in urban areas, such as concrete and asphalt, have higher radiative properties than the surrounding natural landscape and absorb energy from the sun, converting it to heat. SSc5 Heat Island Reduction offers a 1-2 points credit with LEED.
Roofing material with aged SRI equal or greater than the table below can contribute points to this category.
It is important to note that the Cool Roof Rating Council (CRRC) provides 3-yr SRI values based on generalized “color families,” and their approach is conservative and does not reflect the actual performance of each color.
Energy and Atmosphere
The next category is Energy and Atmosphere and specifically the Optimize Energy Performance – Option 2, where metal panels can contribute points. Roofing materials that meet the LEED minimum requirements for SRI are included in the energy simulation model that predicts energy costs, contributing to the total predicted energy cost savings for a building. Cool metal roofs contribute points by meeting the minimum SRI values that contribute to energy conservation. The percentage savings from a cool roof vary based on several factors, like climate zone, building geometry, and HVAC system type.
Materials and Resources
The Materials and Resources category is where metal roof and wall products can contribute the most points. In today’s blog, we will focus on the Building Life-Cycle Reduction Option 4: Whole-Building Life Cycle Assessment.
For new construction projects where a life-cycle assessment is being conducted for its structure and enclosure, a metal panel manufacturer with an Environmental Product Declaration (EPD) can contribute one point. Metal roofs and walls are considered part of a building’s structure and enclosure and the manufacturer’s EPD can be used to conduct a Life Cycle Assessment of the project’s structure and enclosure. There are opportunities to achieve additional points through Pathway 2 through Pathway 4 if it can be demonstrated that there is a reduction three of the six impact categories, such as global warming potential or depletion of the stratospheric ozone layer
Indoor Environmental Quality
Indoor Environmental Quality is focused on reducing chemical contaminants that can damage indoor air quality and human health. Metal complies as an inherently non-emitting source and as an inherently non-emitting source, metal panels used in an interior wall application contributing zero VOCs to the VOC budget calculations. Metal panels can be used in interior applications and sealant is not required when installed for interior use. The paint on a metal panel is factory-applied and cured resulting in the final product being an inherently non-emitting source. This qualification can earn 1-3 points.
Overall, metal roofing and siding can contribute to your green design and LEED certification.
To learn more visit our Sustainability page.
Get started on your metal journey today!
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