Reflectivity vs. Emissivity
Reflectivity
Reflectivity is the ability of an object to reflect light off of its surface.
In the case of commercial roofing, a white single ply membrane or white coating has a greater ability to reflect light than obsolete systems such as a built-up roof.
A white roof will increase the amount of reflected light from the sun compared to any dark roofing material. However, BEWARE! It's important to understand that not all white roofs will give you the same return on your electric costs. Why? Because reflectivity and emissivity are not the same.
Emissivity
Emissivity is the ability of an object to emit heat/energy. Depending on the type of material you are working with, a highly reflective surface may have a low emissivity factor.
For example: A shiny new Snap On tool is highly reflective, but if you set it in the hot Texas sun for a short time and come back to pick it up, it will be almost too hot to touch. See, although the tool has a great ability to reflect, its ability to emit heat is very low.
White IS the New Green…but not all White is the Same!
In recent years it’s become a popular saying that “White is the new Green.” In a nutshell, this means that white roofs are great for the environment because they save on things like energy costs when compared to the old tar and asphalt roofs. However, when it comes to white roofs, you will find that not all roofing systems have the same ability to emit heat. When a roofing system cannot emit heat it will absorb it, and transfer heat to the interior of the building. In turn, this will cause higher electric bills and shorten the life of the building's cooling system.
Monument recently recorded a video that shows how well the Duro-Last System emits heat compared to a Built-Up Roof and a Built-Up Roof with white spray foam. To view this video please visit our Facebook page or YouTube page. Search Monument Roofing Systems and find the video labeled Duro-Last Temperature Test.
Decking: 145
Built-Up Roof: 131
Spray Foam: 131
Duro-Last: 88
The Duro-Last system outperformed the others by leaps and bounds! So, what's the difference? Emissivity! The Duro-Last Roofing system has the ability to emit the heat, creating extensively lower cooling costs for your investment.
Monument Roofing Systems (800) 580-9343 www.monumentgreenroof.com
Article By: Andrea Brown