Using cool roofs

Overhead view of cool roof painting.
What you should know
Step 1: Choose the right passive strategies

Take stock of the current situation. In order to choose the right passive strategies, you need to consider how you use and maintain your building and where it is located.

My building does not use air conditioning — I want to be more comfortable

Many buildings, including some homes, schools, community centers, and religious facilities, are not cooled using mechanical systems like air conditioning. In buildings like these, passive strategies can help people feel more comfortable.

If your building is in a climate that experiences warm or hot temperatures during some or all of the year, the most effective passive strategies are:

My building uses air conditioning — I want to save energy

Some buildings, like clinics, remote offices, storage facilities for medicines or agricultural products, and other kinds of facilities, must be cooled mechanically using air conditioning. It is important to implement passive cooling strategies on these buildings to reduce energy demand and save money. This is true whether you use air conditioning to cool some or all of your building.

If your building is in a climate that experiences warm or hot temperatures during some or all of the year, the most effective passive strategies are:
Step 2: Plan for implementation

It is easiest and cheapest to switch to a cool roof as part of a regular installation or maintenance cycle.

The roof of your current building will need repair or replacement from time to time. This is the best time to switch to a cool roof because it means you were already planning to do the necessary work and don't have to spend extra money to do it again.

If your building is in a location that has a wet season and a dry season, plan to do the implementation during the dry season. Most products can only be installed in dry weather, and planning for this will prevent delays.
Step 3: Find the right product

Finding the right product means finding a product that is compatible with your roof and provides the right balance of cost, durability, performance, and ease of installation.

Finding products near you

Cool roof products are very similar to other kinds of coating or paint products and are made by many different suppliers around the world. If possible, work a domestic supplier of cool roof materials. There are a few ways to look for products near you:
It may be difficult to find products available locally, and you may even find that importation is required. Importation can be a complex and expensive process, so it is worth taking extra time to continue to search for products available locally.

Choosing between products

Once you have identified available products, you will need to choose the one that is right for you. This will be a product that is compatible with your roof and offers the right balance of cost, durability, performance, and ease of installation. You may be able to save money by selecting a dual-purpose cool roof product that also provides waterproofing.

Request cost information and a product data sheet (or technical data sheet) from the supplier. This will provide you with all the information you need to make a decision.


There are many different kinds of roof surface materials, including concrete, metal, fibrecement, and more. Fortunately, there are cool roof products for nearly every roof surface type. Different cool roof products will be compatible with different roof surface materials or will require different installation steps. For example, a product may require that you add two coats instead of one if you are applying to concrete.

The product data sheet should tell you if the product is compatible with your roof material and if there are any special instructions for applying it to that material. If the data sheet does not include that information, confirm with the product supplier that the product is compatible with your roof.


The total cost of the installation will include tools, logistics, and labor, plus the cool roof product itself. You can expect a total cost of approximately $5-15 USD per square meter of roof area unless importation is required.

The cost of the cool roof product itself will depend on performance and durability, but may be about $3 USD per square meter of roof area. Products may be more expensive if they are rated to last for longer, or if they offer higher reflectance or emittance. Products typically come in 19-liter containers, but they may be cheaper if you are able to buy in bulk.

In order to calculate the cost of different cool roof products, it is important to consider the coverage rate and whether multiple coats are needed. Coverage rate describes how much roof area can be coated using one liter of product. A concrete roof may have a lower coverage rate than a metal roof because the product is absorbed into the concrete and more is needed to achieve a reflective final appearance. Information about the coverage rate can be found in the product data sheet.

Below is an example that shows how coverage rate and the number of coats needed can affect the cost of different cool roof products. Product 1 costs less per container and has a higher coverage rate, but Product 2 is less expensive overall because it requires only one coat.

For a building with a roof area of 100 m2:
Product 1 Product 2
Cost per 19L container $40 USD $50 USD
Coverage rate 1 m2/L 0.67 m2/L
Number of coats needed 2 1
Total volume of product needed* 200 L 150 L
Number of containers needed** 11 8
Total cost of product $440 USD $400 USD
* Total volume = (Roof area * Number of coats) / Coverage rate
** Number of containers (round up) = Total volume / Volume per container


Product durability will be rated in years. Some low-cost products may only be durable for three years, while others are durable for five years, seven years, or longer. Information about durability should be included in the product data sheet.

It is important to consider durability when assessing cost. A product that is low cost but needs to be replaced often may be more expensive over time than a higher-cost option that is more durable.


Cool roof performance is usually characterized using measurements of solar reflectance (or reflectivity) and thermal emittance (or emissivity). A high performing cool roof will have a high solar reflectance (>70%) and high thermal emissitance (>75%). Sometimes you might see these combined into one number, called the Solar Reflectance Index (SRI), where high performing cool roof will have a high SRI (>82).

Cool roof performance decreases over time as the product ages from exposure to ultraviolet light, rain, and other environmental factors. You may see different ratings for a product, an initial rating and a 3-year aged rating.

This information is sometimes listed on the product data sheet or the manufacturer's website. If you can't find it, don't worry — know that white and light-colored coatings will almost always perform better than red or dark colored roofs, including shiny metal roofs.

Ease of installation

Most cool roof products are liquid-applied coatings that are easy to install using common tools, like brooms and rolling brushes. There will not be a significant difference between coating products in this regard.

Other kinds of cool roof products, like shingles, roof tiles, and membranes, will require different skills and tools, and may be more difficult to install.

The product data sheet will include more information about how to install the product.


There are many dual-purpose products that provide cool roof performance and waterproofing. These products may help you save money — if you already require a waterproofing layer for your roof, you can get cool roof performance at little or no additional cost.

However, make sure the product is certified to be used for waterproofing if you intend to use it for this purpose. Not all cool roof products provide this benefit, and you risk allowing leaks if you do not provide proper waterproofing for your roof. Read the product data sheet or check with the product supplier to confirm that the product is waterproof.
Step 4: Prepare for installation

You will need to get the right tools and make repairs to your existing roof if necessary.

Installation of cool roof products, especially coatings, can be straightforward using commonly available tools like a broom, brush, and roller. Read the product data sheet or contact the product supplier to understand installation steps required for your product, and identify and procure any tools you will need that you do not have. Make sure you have necessary safety equipment for working on the roof.

If you are applying a cool roof product to an existing building, you will need to check that the roof is in good condition. Clean it of debris and repair any holes using sealant according to instructions from the sealant supplier.

Wait for a period of good weather.
Step 5: Install your cool roof

Be sure to follow safe practices for working on a roof, including using safety equipment and taking breaks.

Safety is of paramount importance. Anyone working on the roof should use safety equipment, be trained to use necessary tools, and understand the steps required to complete the installation. Use sunscreen and take water and shade breaks if working for a long time in the sun.

Make sure to follow installation instructions carefully. Apply the number of coats specified at the required thickness. Once work is complete, remove any tools and leave the roof clean.
Step 6: Maintain your cool roof

Plan for regular maintenance to make sure your cool roof provides the benefits you expect.

Cool roof products will degrade over time as they are exposed to the environment, but regular maintenance is important to keep them performing well and in the best possible condition. Review the product data sheet or speak to the product supplier to understand maintenance requirements.

From time to time, clear the roof of dirt, debris, and anything growing. If you used a cool roof coating product, apply a refresher coat from time to time according to supplier instructions.

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