Cool Roofs And Title 24
Cool roofs are now a prescriptive requirement for both low-slope and steep-slope roof applications on residential buildings. The Title 24 standards do not require a cool roof on a residence whenenergy compliance is achieved using the performance method.
Roofing products with high solar reflectance and thermal emittance are referred to as cool roof, which is the outer layer or exterior surface of a roof. As the term implies, the temperature of acool roof is lower on hot sunny days than a conventional roof, reducing cooling loads and the energy required to provide air conditioning. Optional compliance credit may be taken when a cool roof isinstalled using the performance approach. The credit is available only if there is no radiant barrier installed.
The benefit of a high reflectance roof surface is obvious. While dark surfaces absorb the suns energy and become hot, light-coloredsurfaces reflect solar energy and stay cooler. High emittance is also important. Emittance refers to the ability of heat to escape from a surface once it is absorbed. Surfaces with low emittance contribute to the transmission of heat into the roof components under the roof surface. Because of this increase of heat, the buildings air conditioning load willincrease resulting in higher energy usage and less comfort for the occupants. High-emitting roof surfaces give off absorbed heat relatively quickly through the path of least resistance which isupward and out of the building.
Measuring A Cool Roof System
The Cool Roof Rating Council is a not-for-profit organization that validates the reflective and emissive properties of cool roof products. The Cool Roof Rating Council accepts test reports from approved testing laboratories and then compiles the information in an easily accessed database. It is important to note that any roof covering product can be listed in the Cool Roof Rating Council database. Just because a product appears in the database does not necessarily mean it meets the requirements of either Title 24 or Energy Star.
There are three values used to define the relevant properties of a roof covering. The first is total solar reflectivity . TSR is a measure of the amount of the entire solar spectrum that the roof reflects. This includes ultraviolet , visible and IR radiation. TSR is measured on a scale from 0 to 1. The higher the value, the more solar energy, particularly IR, the material reflects.
The second value is thermal emittance . This is a measure of the materials ability to emit heat to the atmosphere instead of letting that heat energy absorb into the building. TE is also measured from 0 to 1. The higher the value, the more heat the material emits.
How To Naturally Cool Your Home
To keep your home cool without relying on power-draining air conditioning systems, there are some energy-efficient options.
Ceiling fans, heat blocking curtains and blinds, green insulation materials, and making use of the coolest part of the house during different times of the day can reduce your reliance on air conditioning and other energy-demanding methods.
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Other Benefits These Roofs Offer
Its not just your wallet and the planet that can save a lot with cool roofing systems, but there are other benefits as well. Consider these while youre weighing up whether a cool roof is the way to go for your house.
- More comfortable living
Having cool and regulated temperatures inside your house without relying on air-conditioning makes for a more comfortable living experience.
- Low maintenance
A cool roof system requires minimal maintenance once its installed and as a more durable option, has been built to stay with your home for many years.
- Heat Island Index
With everyone committing to cool roofs, the heat island index will drop, which means the entire neighborhood and community can benefit from lower temperatures day and night.
- Lower air pollution
With a decrease in the number of air conditioners being used, youll notice an obvious decrease in air pollution and harmful emissions. The air quality will also improve which means a healthier way of life.
What Are The Cons
As with most home improvements you are going to face some cons. Cool roofs definitely have more positives than cons but its good to be aware of the considered cons.
The main cons that are associated with a cool roof are that you are more limited on materials and color options compared to a standard roof.
There is also a higher cost that comes with certain materials and methods that you use, if you live somewhere that you need heating in the winter it can also lead to higher heating bills in the cold months. In some areas installing a cool roof can void warranties but not in all, so its worth bearing this in mind and doing your research.
To combat these cons, however, some local government and energy companies are now offering a rebate to customers who install a cool roof on their property.
Whilst heating costs can rise in the winter for homeowners with a cool roof, going cool might be more efficient overall, its best for you to crunch the numbers as homeowners who live somewhere that has more warm than cold weather are still going to better off with a cool roof.
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Truth : It’s All About Reflectivity
A cool roof reflects the sun’s rays away from the roof, helping to reduce rooftop temperatures. While a sunlight-absorbing black roof can reach up to 190°F in the summer, a reflective roof’s temperature can be as much as 55°F lower. Dark surfaces also contribute to the urban heat island effect.
A cool roof reflects away the sun’s rays, unlike a dark roof which absorbs them and transfers heat to the building below.
So What Is A Cool Roof
A cool roof is either constructed from or covered with a material that is designed to reflect the suns radiation.
Its something that is extremely popular in areas that experience scorching summer temperatures and dont drop to freezing lows.
Having a cool roof can save homeowners and businesses a decent amount of money on air conditioning costs.
Its not clear at the moment whether a cool roof falls under the solar-based energy-saving technology that is protected by law. There are many states including Texas that have solar access laws in place to prevent HOAs from prohibiting solar energy measures or devices, these may apply to cool roofing materials too.
There are many different ways that a roof can be made cool. Firstly, a roof can be made cool with the use of naturally colling materials like ceramic tiles or metal.
The roof can also be painted with a solar-reflective or white paint. Solar-refective paint comes in a variety of colors ranging from light to dark.
Its worth noting that the lighter colors are seen as more effective. You can also get radiation-blocking coatings applied to the inside of your roof, or opt for a protective membrane to cover the surface of your roof.
Some of these options might not follow the standards set by your community CC& Rs, so its always best to make sure you are checking what youre options are first.
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What Are The Benefits Of Cool Roofs
Cool roofs have several benefits for both for building owners and the environment.
- Keeping buildings cooler on hot days to improve indoor comfort and safety
- Reducing building air conditioning costs and reducing the strain on the electrical grid during peak energy demands
- Reducing the pollution and greenhouse gas emissions associated with building energy use
- Contributing to lower temperatures in the surrounding air which helps reduce the urban heat island effect in cities. EPA has detailed information on how cool roofs can help communities reduce heat island impacts and risks at .
What Are The Benefits Of A Cool Roof For Home Owners
A residential cool roof can deliver multiple benefits for homeowners.
- Lowering the temperature in areas of your home that dont have air conditioning.
- Effectively expand the life of your roof by 30% compared to traditional roofing systems.
- Reduce energy bills by lowering your energy consumption and improving your cost-benefits over time.
- Help reduce local air temperature thus making you a partner in conserving the environment.
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How Do Cool Roofs Work
Through a mix of materials and with the help of a special, reflective coating, reflective roofs reflect more sunlight than traditional roofs. The coatings come in a variety of colors and styles, meaning curb appeal doesnt have to be sacrificed. And they can lower a homes temperature significantly.
As all roof coatings do, reflective roofs help extend a roofs lifespan because of its film coating taking the hit from weather conditions. This makes a roof both more cost- and energy-efficient.
The coatings come with two big benefits: they contain a high level of thermal emittance, meaning they can shed heat. Additionally, through solar reflectance, they can reflect sunlight away from your home. Together, those factors keep a home cooler.
Selecting The Right Roof
Cool roofs can be installed on residential and commercial buildings. There are 2 basic types of roofs: sloped and low-sloped . A low-sloped roof is generally a roof with a pitch that is less than or equal to 2:12 . Some common cool roof materials include membranes, shingles, coatings, stone/rock, metal, and tile with high solar reflectance. Other cool roof strategies include ballasted roofing and green roofs. Learn more about roof types and product types from the Cool Roof Rating Council .
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What Are Cool Roofs
- A cool roof is made of a material or has a coating that can lower the roof surface temperature, decreasing the amount of heat transferred into a residential or commercial building. In general, traditional roofs absorb sunlight during the day, heating the building and the surrounding air. Roofs that are lighter in color or are reflective stay cooler than roofs that absorb sunlight.
- There are two ways to help cool a roof. First, a cool roof can reflect away sunlight, so it stays cooler. Such a roof is said to have a high solar reflectance. Second, a cool roof should also release or emit heat so it stays cool. Such a roof is said to have high thermal emittance. An ideal cool roof is a roof with both high solar reflectance and high thermal emittance . While lighter color roofs tend to have the best SR and TE, new coating and material technologies now exist for other colors that have high SR and TE.
- Exterior building walls are exposed to only about half the amount of sun as roofs, but they can also absorb heat. The same basic principles apply to cool walls as to cool roofs.
What Do Reflective Roofs Cost
The cost to install reflective roofing relies greatly on the size of your home and roof.
That said, the price is considered inexpensive when adding a reflective coating to an existing roof starting as low as 15 cents per square foot and marginal when being added from the front end of a roof replacement. Thats because shingles can come pre-fabbed with a coating or homeowners can ask a roofing contractor to factor the coating into their installation quote.
Reflective roof materials come with an extensive variety. Shingles can be treated, tiles can be glazed, wood can be cool-colored and metal can be factory coated. Its important to discuss your options with a professional roof contractor when it comes to reflective roof configurations. Thats because even a small pin-hole in a reflective roof coating can hurt the integrity of the entire project and cause more damage to your roof.
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Truth : On Average Electricity Costs Up To 4 Times More Per Btu Than Natural Gas
If your building uses electric air conditioning and natural gas heat, a cool reflective roof can help lower your cooling costs* no matter where you are in the continental United States by reducing the amount of air conditioning needed.
On average, electricity costs up to 4 times more, per BTU, than natural gas. Not only is electricity more expensive than gas, but the rate structures are more complex. Seemingly small increases in electricity use can result in large additional costs due to the compounding effects of time of demand charges based on a few peak minutes of electricity usage during each billing period.
How much could you be saving on energy bills? Find out by trying out our CREST energy calculator.
What Is A Cool Roof For Residential
A cool roof is a roofing system that has been designed to reflect more sunlight and absorb less heat than a standard roof. A cool roof can be made of a variety of materials, including metal, asphalt, tile, and even white concrete.
A cool roof can help reduce the amount of heat that enters a home, which can save money on cooling costs. In addition, a cool roof can extend the life of a roof by reducing the amount of heat damage that can occur over time.
There are a few things to consider when choosing a cool roof for a home. The first is the climate. If a home is located in an area with hot summers and cold winters, a cool roof may not be the best option.
The second is the type of roof. Some roofs are better suited for a cool roof than others.Metal roofs are a good choice for a cool roof. They reflect sunlight and heat well, and they are durable.
Asphalt roofs are also a good choice, but they can be more difficult to install. Tile roofs are another option, but they can be expensive.
White concrete is another material that can be used for a cool roof. White concrete reflects sunlight and heat well, and it is also very durable
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How Much Can A Cool Roof Save Me
- According to Lawrence Berkeley National Lab Heat Island Group on a typical summer afternoon a clean white roof that reflects 80% of sunlight will stay about 50°F cooler than a grey roof that reflects only 20% of sunlight.
- In general, cool roofs work best in hot sunny climates, like the Southern U.S., on buildings with low levels of roof insulation. Energy savings for buildings with cool roofs in Northern climates are predicted to grow as the climate warms.
Benefits Of Cool Roofs
A Stronger Roof: A potential more durable roof, with a longer lifespan and fewer maintenance costs.
Temperature Reduction: Significantly reduced temperatures during the summer, including the internal temperature of the home or building, especially compared to traditional cooling techniques.
Lower Utility Use and Cost: Due to a residential cool roof significantly reducing temperatures internally and externally, homeowners will have to rely less on their air conditioning system. As a result, homeowners can spend less on their energy bills.
Reduced Heat Island Effect: The heat island effect is a common issue in urban environments, and by installing cool roof solutions in those areas, the buildings overall temperature will not only be lowered, the surrounding area will be as well.
Reduced Air Pollution: When people use their AC systems, it reduces the burning of fossil fuels, and therefore reduces the admission of harmful greenhouse gasses. As a result, it can also lead to higher air quality, due to the reduction of these harmful emissions that lead to issues like smog in certain places.
Utility Rebates: Another benefit to cool roof installation is the fact that there are several utility rebates that may allow you to earn back your initial cool roof shingles cost, and then continue to save you money over time.
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What Is The Cost Of A Cool Roof
The cost difference between a cool roof and a traditional roofing system is almost the same. However, with a cool roof, you get the added benefit of cost-savings in the long run.
The actual cost of your residential cool roof installation, repair, or replacement will naturally depend on the size of your roof. The main cost will also include the installation costs as well as labor, materials, and maintenance costs. These, however, are upfront costs that will be easily balanced out in the long-term via the reduction in your energy bills, rebates, and incentives.
A cool roof helps reduce your dependency on air conditioning while effectively extending the lifetime of the roof by around 30% when compared to traditional roofing systems!
The Energy And Cost Savings Of A Cool Roof
The main reason for people to have a cool roof installed is to save money and decrease their energy usage, and this is done by reducing your reliance on electronic cooling systems like fans and air conditioners.
According to the Green Building Alliance, a cool roof can use up to 40% less energy to keep your home cooler than the average building.
The costs you can save will depend on a few things, like the size of the roof, its condition, accessibility, and which coating or technique you decide on. Choosing one thats easy to install and will last a long time is key to maximizing these savings, but eventually, they will pay for themselves with the saved costs of utility bills.
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A Final Key Measurement: The Solar Reflectance Index
The Solar Reflectance Index, or SRI, is a calculation using the aged solar reflectance and thermal emittance measurements of the asphalt shingles materials. It ranges from 0 to 100.
This measurement can be used as an indicator of how hot shingles are likely to become when theyre exposed to the sun. The lower the SRI value, the hotter the asphalt shingles are likely to be in sunlight. Conversely, roofing shingles with a higher SRI will help reduce the cooling load on your home.
In many cases, asphalt shingle manufacturers use a shingles third-party certified aged SRI value to demonstrate compliance with cool roof energy codes.