Workers retrofitting a home with a cool roof in the desert with spray foam polyurethane cool roof coating

Cool roofs are an up-and-coming technology that can be a sustainable way to reduce energy costs and elongate the life of your roof. Cool roofs can be a cost-effective way for people living in warmer climates to make their homes more energy-efficient. 

As with most things, cool roofs have both pros and cons. This article will break down everything you need to know about cool roofs and how they can help your home be more efficient. 

What are Cool Roofs?

Cool roofs are a newer technology inspired by Greek designs. In Greece, the homes and roofs are white to reflect the light from the sun and keep homes cool. Similarly, cool roofs are designed to reflect heat from the sun. 

Most roofs in the U.S. are black or dark-colored and are designed to absorb heat, making it difficult for homes in warmer climates to maintain a cool temperature. On a hot day, a roof that absorbs heat will naturally heat the inside of your home, putting added stress on your air conditioner to keep your home cool and, as a result, driving up energy costs. 

Cool roofs are designed to do just the opposite. They reflect the sunlight, naturally keeping the structure cool and, as a result, reducing the energy costs necessary to keep it cool. Cool roofs can be installed on existing and new structures. 

Cool roofs are highly impactful in warmer climates where even a few degrees in a home can make a massive difference in energy usage. They can also be used in cooler climates and are highly impactful during the summer months. 

Why Consider Cool Roofs?

Most material used in roofing absorbs energy, naturally heating the inside of a home. In warmer climates, added heat from the roof can be brutal on cooling costs and comfort levels. Cool roofs reflect light, not absorb it, keeping homes naturally cooler, thus increasing energy efficiency. 

Types of Cool Roofs

There are a few types of cool roofs that have different applications based on your need and situation. For example, someone building a new structure has different needs than someone in an existing home that wants to make it more energy-efficient. 

Coated Cool Roofs

If you live in a structure with a standard roof, you can make your current roof “cool.” A solar reflective coating can be applied to existing roofs to make them cool roofs. In addition, there are a plethora of types of cool roofing coats for both new and existing roofs to make them more energy-efficient. 

Here are some of the types of cool roof coatings: 

White Roof Coatings 

White roof coatings reflect 70-80% of the sun’s solar rays. This number can increase if the contractor layers the coating thicker. White roofing coats are opaque and use a polymer and white pigment to achieve high efficiency. 

Workers retrofitting a home with a cool roof in the desert
Workers retrofitting a home with a cool roof. Courtesy of Entreplanos.

Aluminum Roof Coatings

These coatings aren’t straight aluminum like the name sounds. Instead, it is a thick resin that includes aluminum leafing flakes. 

Aluminum coatings are highly effective in reflecting the sun and have been known to reduce the indoor temperature by 15 to 20 degrees Fahrenheit. Most aluminum roof coatings reflect 50% or more of the sun’s rays, and some are over 70%. 

Pigmented Coatings

Pigmented coatings are colored coatings that contractors install on an existing roof. They could be green, red, blue, or another color as well.

Unfortunately, this is not the most efficient coating; it typically reflects 20% of the sun’s rays. However, even reflecting 20% of the sunlight can positively impact energy usage in your home.

Roofing Membranes

Roofing membranes are waterproof, high-strength, and quite flexible. These membranes use high-quality material attached to the roof, including asphalt, synthetic, rubber, or synthetic polymers, and come in black or white. 

The materials used include felt, fiberglass, or polyester. Not only are roofing membranes easy to repair, but they also have low maintenance requirements. 

Built Cool Roofs

For built cool roofs, the material itself acts as the cool roof. So instead of a coating going over an existing roof, these roofs are made with the sun-reflective membrane. These are best for new builds or complete roofing replacements. 

Single-Ply Thermoplastic Membrane

The material in this membrane is a plastic polymer such as PVC, which is durable and highly effective. 

Thermoplastic membranes are a very up-and-coming usage of plastic polymers that will become more common in the next few years. They are typically white but can be different colors as well. 

A standard single-ply thermoplastic membrane roof reflects 80% of the solar rays and is one of the most efficient options for a cool roof. 

Clay and Concrete Tiles

These options are both extremely durable and reflect a decent amount of sunlight. They are known to reflect over 80% of the sun’s rays.

Clay tiles being installed to create a cool roof
Courtesy of American Coating Association

Clay tiles are quite common in some areas of the United States and are great because you can recycle them at the end of their lifespan. Concrete is also very durable and is excellent for extreme weather areas that could benefit from a cool roof. 

Pros of Cool Roofs

Cool roofs provide many benefits for homeowners and can be essential in making a home more efficient and reducing energy costs. Here’s a more in-depth look at the advantages of cool roofs.

Naturally Lowering the Temperature in Your Home

Cool roofs are a great way to naturally lower the temperature in your home.

If you live in a warm climate year-round, an inefficient roof can significantly impact the long-term temperature of your home. Just having a cooling roof can reduce the temperature in your home by 15 to 20 degrees Fahrenheit. 

Lower Energy Bills and Usage

By lowering the starting temperature of your house, you immediately start saving money because your air conditioner does not have to work as hard or as often to keep your home at the desired temperature.

In addition, studies have shown that cool roofs decrease energy usage by about 40% and reduce energy costs by 7% to 15%. Over a year and the lifespan of your home, this can add up significantly. 

Global Warming Mitigation

Cool roofs offer global warming mitigation on several levels. First, it helps reduce emissions into the atmosphere.

If air conditioners don’t run as often to keep homes cool, they will not release as many emissions. This is a natural occurrence that happens when you install a cool roof. 

Additionally, because the roofs reflect the light and don’t absorb it, it reduces the temperature of the area around the roof as well.

The reduction can impact the urban heat island effect, which occurs when pavement and surfaces absorb heat and, as a result, make a small area, such as a city, warmer. 

A closeup of a green roof in an urban environment
Green roofs are a type of cool roof that are particularly effective in combatting the urban heat island effect.

Cool roofs naturally keep the area around them cooler and can impact the ambient air temperature in a given area. 

Lower Maintenance Costs

The maintenance on roofs can be costly; however, cool roofs do not need much, if any, care, which is one of the most significant benefits of a cool roof. They save money on energy bills but also limit the need to spend money on maintaining the efficiency of the roof. 

Longer Lifespan

A standard roof lasts for about ten years before needing replacing. A cool roof has a lifespan of 15 to 30 years, depending on what type you have. Cool roofs reduce waste in the environment by having a longer lifespan. 

Incentives 

Organizations offer incentives to install cool roofs, including rebates. Because there are so many environmental benefits to cool roofs, most of these organizations are environmental-based, such as the Green Building Alliance. 

Cons of Cool Roofs

As with anything, there are some downsides to cool roofs. Therefore, it is essential to know the cons before deciding to install a cool roof on your home. Luckily, there are not many, and for most people, the advantages of a cool roof will far outweigh the negatives. 

Expensive to Install

You can expect a considerable upfront cost for cool roofs. They are more expensive than a standard roof; however, they have a great return on investment, which a typical roof does not have.

Cool roofs typically cost between $.75 and $3 per square foot, which is more expensive than traditional roofs.

Cool roof companies can help you identify the best option for your home and your budget. It is worth a phone call or meeting with a company before writing off cool roofs because of the initial cost. 

More Likely to Have Mold

For hot, dry climates, this will not be an issue. But it is something to take note of for humid climates.

Cool roofs tend to be more susceptible to mold, which could hurt the efficiency and effectiveness of the roof if not identified. Contractors can apply chemicals to the cool roof to prevent mold from growing. Chemical applications only last a few years, though, and you may need to reapply several times during the roof’s lifespan. 

Show Dirt Easier

Because cool roofs tend to be lighter in color, they show dirt and debris more easily than standard roofs, which are dark. However, dirt is an aesthetic issue and doesn’t typically affect the ability of the roof to be effective.

Can be Inefficient in Cool Temperatures

In cooler climates, cool roofs are excellent in the summertime. They perform flawlessly and reduce air conditioning costs and a home’s temperature just like it would in warmer climates.

Unfortunately, a standard roof absorbing heat during winter is actually a benefit because it reduces heating costs in a home. However, a cool roof will still reflect the sunlight, so heaters will have to work harder to keep the home warm. 

If you live somewhere with milder temperatures or more warm days than cold days, a cool roof can still be effective and positively impact your home and the environment. However, if you live in an area that has more cold days than warm days, it may not be the most effective choice of roofing material. 

Conclusion

Cool roofs are an excellent way to reduce energy usage and costs while making your home a more comfortable natural temperature. Cool roof options are available, whether you want to put a coating on your roof or replace it entirely. 

Cool roofs have many benefits that include long-term cost and energy savings, long life spans, and a positive impact on your home’s surrounding environment. 

Cool roofs are specific to climate and may not be efficient in cooler temperatures. They can also be susceptible to mold in areas with a higher humidity level.

However, despite their higher initial costs, overall cool roofs are a worthy investment. They have a great return on investment, and the money spent will be well worth it.

One of the most helpful things to do if you are considering a cool roof is to meet with a contractor. They are highly knowledgeable, and many will do an initial consultation for free.

In addition, contractors who install cool roofs can help you decide if it is a good choice for your home and provide advice on the best type of cool roof to install.

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