Cool Roofs
Frequently Asked Questions (FAQs)
Credit: AdobeStock_224202625
Have questions about Cool Roofs? We have answers.
On this page you will find some of the common questions about Cool Roofs, and detailed answers for each one.
If you have a question that isn't included as part of this frequently asked questions (FAQs), please let us know by contacting Sasha Shyduroff ([email protected]).
Frequently Asked Questions (FAQs)
What is a Cool Roof?
How are Cool Roofs installed?
What are the benefits of a Cool Roof?
What homes/buildings can benefit the most from Cool Roofs?
How much does a Cool Roof cost?
Can my roof be converted to a Cool Roof?
Does a Cool Roof have to be white?
What is the Cool Roof “heating penalty?”
What about solar energy or HVAC equipment on my roof?
Do Cool Roofs require special maintenance?
When should I convert my roof?
What other climate-smart roof options are there?
What is a Cool Roof?
Cool roofs (also known as white roofs or reflective roofs) are simply roofs designed to reflect more sunlight than a conventional roof. By reflecting more sunlight, the roofs absorb less heat, keeping the building and surrounding area cooler.
Image Description: A light orange and white background. A yellow sun outlined in white is in the upper left corner. Bold, blue text says, "Conventional roof reflects 20%." Under the text is a light blue home with a dark grey roof with three white arrows going towards the roof and one white arrow going away from the roof. To the right of this text and house is bold, blue text that says, "cool roof reflects 80%." Under the text is a light blue home with a light grey roof with three white arrows going toward the roof and three white arrows going away from the roof.
How are Cool Roofs installed?
Cool roofs can be achieved either through applying a coating or installing a covering.
Coating
Description: A worker wearing jeans and brown work boots is using a rolling paint brush to put a cool roof coating on a roof.
Covering
Description: Aerial view of a light colored building with a white shingled roof.
Performance
Performance varies based on the type and quality of material selected. Look for materials that are ENERGY STAR certified and have a high solar reflectivity. Explore the solar reflectance index of different materials on the Cool Roof Rating Council’s Directory of Rated Roof Products.
What are the benefits of a Cool Roof?
Cool roofs can provide economic, environmental, and health benefits for residents, property owners, and the broader community.
Economic
Environmental
Health
What homes/buildings can benefit the most from Cool Roofs?
Buildings with the following characteristics typically see the greatest benefits from installing a cool roof.
Dark roofs absorb more heat from sunlight, leading to higher indoor temperatures and increased cooling costs. Cooling material on dark roofs can have a greater impact on heat reduction.
How much does a Cool Roof cost?
The cost of a cool roof depends on the roof size, cool roof product (e.g., coatings, membranes, shingles, etc.), installation complexity, and whether it’s a new installation or retrofit. A cool roof coating can cost between $0.50-4.50 per sqft, depending on the material, plus labor.2 Remember to also factor in energy savings when considering cost: a NYC study found that a reflective coating can reduce AC costs by 50% in a one-story building, 25% in a two-story building, and 10% in a five-story building.
Can my roof be converted to a Cool Roof?
Your roof can most likely be converted to a cool roof because cool roofing products and technologies are available for a wide range of roof types. Fortunately, low-sloped (flat) roofs are fairly common in our region, making the application of cool roofs even more feasible. However, whether you have a low-sloped or pitched roof, there are cool roof solutions available for you.
MAPC’s Cool Roof Site Suitability Tool and Self-Assessment can help you determine if a cool roof is feasible and beneficial for your building. While the mapping tool is only available for buildings in the Metro Mayors region3, the Self-Assessment is available for any building. Consult with a local roofing contractor experienced in cool roof installations to assess your specific roof type and determine the most suitable cool roof solution.
Does a Cool Roof have to be white?
Cool roofs come in a variety of colors and materials. While lighter colored roofs tend to be better at lowering temperatures, a cool roof does not have to be white! There are “cooler” versions of dark-colored roof colors and products that can suit your aesthetic preference.
Dark-colored coatings
Dark-colored coatings incorporate reflective pigments or granules into the material that are designed to reflect a higher percentage of sunlight and absorb less heat compared to traditional dark roofing materials. The image below demonstrates how dark-colored cool roof materials are “cooler” than traditional roofs. The value noted is the materials’ solar reflective index (a measure of how well a surface reflects sunlight and heat instead of absorbing it). A higher number indicates a cooler roof. White roofs can have a solar reflective index of 60-90%.
Image /source: American Rooftile Coatings
Image Description: Provides information on Cool Roofs versus Traditional Roofs.
Cool Roof: Black (p=.41), Blue (p=.44), Gray (p=.44), Terracotta (p=.48), Green (p=.46), Chocolate (p=.41).
Traditional Roof: Black (p=.04), Blue (p=.18), Gray (p=.21), Terracotta (p=.33), Green (p=.17), Chocolate (p=.12)
Non-white Cool Coverings
Cool coverings, such as cool shingles, use innovative materials and technologies that enhance their reflective properties.
CoolRoofOwens: Samples of cool-roof shingles and colors; several companies manufacture similar tiles in a variety of colors. (Monica Kelly)
Image Description: Provides images of different colors of roof shillings. Frosted Oak (a lighter brown), Harbor Fog (a medium gray), Sage (light yellow and green), Sunrise (light to medium brown), Forest Brown (dark brown), Mojave (Terracotta like color), Mountainside (dark gray), and Summerwood (a brownish gray).
What is the Cool Roof “heating penalty?” Should I be concerned?
The “heating penalty” refers to a potential increase in heating bills in the winter months since the roof reflects more heat than it absorbs. While this may occur, it is not a significant issue in our region for several reasons. First, the cost savings from cool roofs in the summer months typically outweigh the penalty in the winter months. Additionally, as the climate shifts towards warmer temperatures, winters are becoming milder, and summers are becoming longer and hotter. This trend increases demand for cooling, further enhancing the value of cool roofs for our region. Finally, the heating penalty is a minimal concern in New England because snow, historically more prevalent in the region, naturally reflects sunlight, acting like a cool roof.
What is the Cool Roof “heating penalty?” Should I be concerned?
The “heating penalty” refers to a potential increase in heating bills in the winter months since the roof reflects more heat than it absorbs. While this may occur, it is not a significant issue in our region for several reasons. First, the cost savings from cool roofs in the summer months typically outweigh the penalty in the winter months. Additionally, as the climate shifts towards warmer temperatures, winters are becoming milder, and summers are becoming longer and hotter. This trend increases demand for cooling, further enhancing the value of cool roofs for our region. Finally, the heating penalty is a minimal concern in New England because snow, historically more prevalent in the region, naturally reflects sunlight, acting like a cool roof.
What if I have (or want) solar energy or HVAC equipment on my roof?
Cool roofs are a great complement to rooftop solar and equipment. Studies have shown that by lowering roof temperatures, cool roofs can improve the efficiency of solar panels, helping them maintain optimal performance and extending their lifespan.* Similarly, cool roofs can enhance the efficiency of HVAC systems by reducing the surrounding temperature, potentially extending their operational lifespan.
If your building already has rooftop solar, you will need to coordinate with your solar developer to temporarily remove the panels while the cool roof coating gets applied and then reinstall the panels again. Talk to your roofer and solar developer about the best approach to ensure a smooth and effective installation process.
If your building does not have rooftop solar but you are planning to install it, it is generally advised to apply/install cool roofs before solar panels so it does not interfere with the panels. Inform both your cool roof contractor and solar developer of your plans to have a cool roof-solar complement at the onset of the project. Once the cool roof is applied or installed, coordinate with the solar developer to install the solar panels.
If your building has rooftop HVAC equipment, plan to delineate pathways on the roof to reach the equipment so you can minimize foot traffic and reduce potential damage to the cool roof.
*Rahmani, Robinson, & Barzegaran, (2021). Cool roof coating impact on roof-mounted photovoltaic solar modules at Texas green power microgrid. International Journal of Electrical Power & Energy Systems.
https://www.sciencedirect.com/science/article/abs/pii/S0142061521001721?via%3Dihub
Do Cool Roofs require special maintenance?
The maintenance required for a cool roof is similar to that of a conventional roof. Precautions should be taken to limit foot traffic to avoid damage or degradation to the reflective coating or covering, which can reduce its effectiveness at reflecting heat. To ensure maximum performance and lifespan, keep the roof clear and free of debris. For roofs with equipment on them, delineate pathways on the roof to access the equipment, minimizing foot traffic and potential damage.
As an added benefit, cool roofs can oftentimes reduce long-term maintenance costs as they last longer by not expanding and contracting from heat absorption. In many cases, cool roofs can extend the warranty of the roof.
When should I convert my roof?
Consider converting to a cool roof if any of the following apply to you:
- If your roof is due for replacement
- If you're experiencing high cooling costs
- If you're planning to install solar panels
- If you're experiencing discomfort due to excessive heat indoors
Cool roofs are a smart choice for new construction or a roof replacement. It is generally not cost-effective to replace a structurally sound roof solely to enhance solar reflectivity, but property owners can consider applying a reflective coating on the existing structure to achieve cool roof benefits.
What other climate-smart roof options are there?
Building owners can explore the following other climate-smart roof solutions:
- Green roof: roofs with basic plant cover such as a garden or small trees. The cooling effect comes from the evaporation of water from plant surfaces.
- Green-blue roof: retains rainwater and has a controlled drainage system that releases water over a 24-hour period. It can be connected to cisterns that store rainwater for reuse, but the roof itself is not a storage system. Can include open water surfaces or be placed beneath paving or shingles.
- Solar roof: Roofs with solar panels mounted onto the roof to generate electricity and absorb heat. Solar roofs are fully compatible with cool roofs.
Compared to other climate-smart roof options, cool roofs are easier and less expensive to install. They are the fastest to install and provide immediate benefits. Also, they do not significantly affect the structural load of a building meaning they can be implemented without requiring major structural modifications or reinforcements.