Cool Roof vs. Green Roof?

1 February 2018
Category Cool Roofing
1 February 2018, Comments 0

Which is better- a Cool Roof or Green Roof?

There’s a lot to choose from when looking at roofing options. Contractors can select from a multitude of roofing options such as cool roofs, green roofs, shingles, plastic, Eco friendly, and the list goes on. When choosing a roofing option, two of them stand out from that rest, and that is; cool roofs and green roofs.

Both have much to offer. A cool roof has the ability to reflect light from the sun, while also reflecting high temperatures back to our atmosphere. A green roof allows light from the sun, and high temperatures to be absorbed prior to it entering the building, and it bounces power off of the atmosphere. Once a green roof or a cool roof has been selected, a contractor can weigh the positives from the negatives in order to find the best option for the property.

Cools roofs serve as a practical option due to the fact they are made from elements that offer light to be reflected. Some ways this is accomplished is through the use of lightly colored coatings, tiles, and paints. Both cool and green roofs help to reduce heat for structures located in heavily populated areas by increasing the “green island effect”. In this effect, taller structures cause disruption in air flow with the combination heat allowance of building surfaces. This often results in an increase in temperature within the environment.

Roofing History

The concept of a green roof may be new to some people, however; They have actually been around for hundreds of years. From as early as 2020 BC, ancient roofs can be traced from an ancient region in southwestern Asia. Roof gardens have also been commonly used in European countries more recently.

The Advantages

What makes the cool and green roofs stand apart from the rest is their visual appeal. Some attractive qualities are noticeably lower energy bills through a decrease in air conditioning use, as well as a decrease in roof temperature. All which can lengthen its service life.

An additional advantage cool and green roofs offer is their positive effect on the environment.  Through cool and green roofing, we can save electricity and avoid power outages.

Another quality a green roof can offer is protection from hail and reduction in noise infiltration. They can even stretch the life of a roofing system by stopping powerful UV rays from immediately coming into contact with the roof membrane.

Positives and Negatives to Consider

Despite the incredible positives associated with green and cool roofs, it’s important to note there are disadvantages to consider. One important consideration to acknowledge when dealing with a green roof is that an irrigation system is needed depending on certain climates. Roof gardens are not guaranteed free maintenance so they have the potential to be costly. Also, fertilization and weeding may be an additional requirement.

Location is also an important consideration when looking at cool and green roofs. For example, those living in the northern part of the U.S typically need more heat, not less. For this reason, a cooling roof would be of no beneficial use to them. Cool roofs generally achieve the most saving in a hot environment.

Lastly, there are possible visual downsides such as a notable glare caused by cool roofs that are reflective. Unfortunately, this glare can be an annoyance towards neighbors, drivers, and businesses nearby. Another downside is the color. Due to its typically white shaded roofs, dirt and dust tend to be more noticeable.

Cost & Energy related Savings

The most important factor to consider when choosing between a cool and green roof is the cost and energy savings. A common myth is that cool roofing installation costs are more expensive than other roofing. This is simply not true. The expense some may be referring to is the conversation of a standard quality roof to a cool roof. This conversion can escalate in expense and should be well considered. However, when adding a new roofing system, owners of buildings have great potential to save money by requesting the contractor add insulation inside the roof system. Interestingly, there may also be an incentive in which you may be offered grants and rebates to counter the cost of a green roof.

Weather Conditions and Environmental Considerations

An important consideration when selecting a cool roof is moisture control. Properties located in humid and typically warm environments should be cautious of mold and algae growth. Fortunately, there are solutions to help prevent that. There are combating agents such as specialized coating, and specific chemicals that serve to fend off any mold growth or algae development.  Not only can cool roofs accumulate moisture in humid environments, but they can also do so in chilly weather conditions as well if not created correctly. In certain locations, cool roofs can move water drops down to an area within the roofing system which results in condensation build up to move onto the roof. To treat this, it is necessary that a vapor barrier be installed. It’s important to note this installation will add to costs. Ultimately, condensation of any kind can be avoided through correct planning and execution.


When choosing between a cool or green roof, it is most important that a contractor critically examine both the benefits and disadvantages. Important factors include, location, weather conditions, cost, and living conditions. Cool and green roofs offer attraction through their energy efficient features and savings costs. However, they can also bring forth various disadvantages depending on the roof. In some cases, it makes sense to choose one roofing system over another. Adding insulation is the finest way to achieve the best energy savings. Make sure to contact a roofing professional to help determine the best option for you and your property!

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