Green roofs are not a new concept either and are one of man’s earliest roofs. Ancient roof gardens were installed as far back as 2020 BC in Mesopotamia, and have been widely used in Europe for more than 70 years.

When selecting a roof, there are many different options, including thermoplastic, EPDM, metal, shingles, greens roofs, and more! While each of these possesses its own advantages and disadvantages, cool roofs and green roofs present facility owners with great options. Cool roofs reflect sunlight and heat back into the atmosphere while green roofs help absorb the sunlight and heat before it can enter the building. After opting to use a green roof or cool roof, consider the pros and cons of both before deciding which would be best for the property.

Cool roofs are a viable option and made of materials that help reflect the sun’s energy through light-colored paints, roof tiles, coatings and shingles. Another option is a vegetative roof that holds plant life and reduces reflective heat. Green and cool roofs help buildings in highly-populated areas stay cool by elevating the “heat island effect.” Streets, parking lots and rooftops contribute to the heat island effect and can bring roof surface temperatures up to 70 degrees hotter than the ambient temperature. Green roofs help a building stabilize air above the roof to near ambient temperature.

Advantages

• Reduces energy bills by decreasing air conditioning needs, improve indoor comfort for spaces that are not air conditioned, and decrease roof temperature - which can extend service life.
• The environmental impact. These roofing options reduce local air temperature and lower peak electricity demands that can help prevent power outages. When a cool roof is used on a power plant, emissions can be reduced, including carbon dioxide, sulfur dioxide, nitrous oxides and mercury.
• Reduction of noise infiltration and hail protection.
• Extends the lifecycle of the roof system by eliminating the UV rays from directly hitting the roof membrane.
• The design to delay, filter, and reduce the volume of storm water runoff. Green roofs typically hold between 50 and 60 percent of storm water, which lessens demand on storm drains.
• Provide an aesthetically pleasing sitting or walking area to building tenants. Tenants are not the only ones that can benefit from a green or garden roof. Having a green or garden roof can provide tenants with the option of creating a habitat for birds and insects.

Disadvantages/Considerations

While there are many advantages to having a cool roof or a green roof, there are also disadvantages and common considerations that come along with these roof systems.

• A green roof needs an irrigation system in certain climates to water the plants, which can be costly and roof gardens are not always maintenance free.
• Depending on the vegetation, weeding and fertilization may also be required.
• Areas in the northern half of the country require more heating cost than cooling cost; in this case there is no advantage to a cool roof.
• Finally, there are also potential aesthetic disadvantages. One of the largest aesthetic disadvantages is that cool, reflective roofs may cause an unwanted glare. Unwanted glare can be a nuisance to neighbors or other businesses that are close by.
• Cool roofs tend to be varying shades of white, making dirt and grime more visible. Green roofs tend to be very heavy; some up to 25 lbs. per square foot when full of water. Many structures simply can’t handle that load.

The idea of installing a cool or green roof is a decision that needs properly evaluated. A few things to consider when selecting a roof system include geography, occupancy, and insulation thickness. There are many appealing aspects to a cool or green roof with aesthetics, reduction of local air temperatures and energy savings. But while these might be appealing, there are many disadvantages and considerations to a cool or green roof. There are also times when it makes sense to go with another type of roofing system. The best way to save energy in a roof system is to add more insulation. Contact our experts to help determine which roof system makes sense for your property.

Schedule a free, no-pressure inspection now by calling 317.643.1207, or book online at http://expertrestorationservice.com.

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