A radiant barrier will reduce cooling costs by reflecting heat and blocking its emissivity. It works well in hot climates and alongside traditional insulation during cold months to keep the warmth inside the home.
A radiant barrier may not be worth the investment if your home has a well-shaded roof, properly sealed air ducts, and energy-efficient windows.
Radiant barriers are essentially foil-like sheets of aluminum that reflect radiant heat where it came from. That differs from traditional insulation, which typically has a foam core that absorbs and holds thermal energy. A properly installed radiant barrier reduces a home’s cooling costs by as much as 17% during the year’s warmest months. That’s a significant amount of money to save, and if you take the time to review your previous utility bills, a radiant barrier will likely pay for itself within ten years.
When used with proper insulation, radiant barriers also effectively reduce heating and cooling costs. That is because they keep radiant heat from escaping through the roof, which keeps the home cooler. However, it’s important to note that radiant barriers alone aren’t enough to effectively reduce your home’s energy bills because they don’t block radiated heat from entering the house.
Radiant barriers must have both a high reflectivity and low emissivity to be effective. They also must be double-sided to perform properly. That means the aluminum must face an open-air space to reflect radiated heat away from the home.
The insulation beneath a radiant barrier must be a foam board or cellulose, not fiberglass. Conventional insulation, such as fiberglass, can sag or delaminate, causing the reflective surface to lose effectiveness. This type of insulation also tends to hold moisture, which can lead to fungal growth in the attic and require a costly dehumidification system.
Foam boards and cellulose are also more resistant to extreme heat and moisture than fiberglass, which may make them a better choice for a radiant barrier. A DIY homeowner can install these products, but hiring a professional installer is best to ensure the installation is done correctly.
Radiant barriers reflect solar energy, decreasing heat build-up on a roof. Typically, aluminum foil is laminated to one or more substrate materials, like cardboard, kraft paper, and oriented strand board. They can also be combined with cellulose or fiberglass insulation to create radiant sheathing. The combination reduces cooling costs and improves the home’s overall energy efficiency.
A radiant barrier is especially important for homes with air-conditioning ducts in the attic, as it keeps them cooler and allows you to use a smaller system, resulting in annual savings of up to $150. However, this is a general rule of thumb, and the precise amount you’ll save depends on how much existing conventional insulation is installed in your attic and the climate zone in which you live.
Without a radiant barrier installed, the sun’s radiant energy enters your house through your attic and warms up your ceilings, causing your air conditioning to work harder. A radiant barrier will block up to 95% of this radiated heat, saving you money year after year. However, radiant barriers must be installed in an open-air space to perform properly; if they are sandwiched between other materials or the attic floor, they become conductors and will not do their job.
If you calculate the present value of your electricity savings using standard economic calculations, a radiant barrier should pay for itself within ten years in most regions of the country. Additionally, energy-efficient features are highly desirable for new home buyers and can increase resale value. If you’re considering adding a radiant barrier to your home, it’s best to shop around and ask for a quote from multiple contractors to see what deal you can get.
Many homeowners are still determining which way a radiant barrier should be installed to get the most benefit. According to the Florida Solar Energy Center research, radiant barriers work best when installed with the foil side facing down and under the roof sheathing. This way, the radiant barrier can reflect the sun’s heat away from the building rather than absorbing and heating it.
Radiant barriers have a high reflectivity and a low emissivity, meaning they only allow a very small amount of radiant heat to pass through into the living space. That means homes with radiant barriers have a much lower energy consumption, especially during the warmest parts of the year.
That is because air conditioning systems do not have to work as hard to cool a home with a radiant barrier installed. According to a study by the Oak Ridge National Laboratory, homes with radiant barriers in their attics can save up to 17% per year on energy bills.
There are several different ways to install a radiant barrier in an attic. Still, the most common is simply laying it on top of existing attic insulation with the reflective side up. In new construction, radiant barriers can be stapled under the attic rafters before installing the roof deck. This method is preferred in warm climates since it allows the radiant barrier to reflect heat from the sun away from the living spaces.
In both installation methods, an air gap must be left for the radiant barrier to do its job. This air gap should be about three-quarters of an inch or larger. That will prevent warm air from escaping the attic into the foil surface of the radiant barrier, which can cause it to lose effectiveness.
There are several different radiant barriers available on the market. The main characteristics to look for are high reflectivity and low emittance. The most common type of radiant barrier is a reflective aluminum foil laminated to a stiffer material for support, which can be paper, plastic, OSB, or other materials. Radiant barriers can be installed as a standalone product or combined with traditional insulation in an attic to reduce heat transfer (radiant, convection, and conduction).
It is important that the reflective side of the radiant barrier faces open air space to perform correctly. It should always be evenly distributed between two materials, which will cause it to act as a conductor instead of a reflector. That can significantly reduce its efficiency, and installing them this way in attics is not recommended.
When installed properly, radiant barriers can significantly reduce cooling costs in homes with air ducts in the attic. In a hot climate, this can translate to savings of up to 16% on energy bills. These savings are primarily due to lower air-conditioning run times, fewer over-exertions of the system, and a reduction in peak cooling loads.
For the best results, radiant barriers should be combined with traditional attic floor insulation to protect against all three types of heat transfer. That will ensure the entire home is insulated and maximize the benefits of reduced energy bills and improved comfort. If you are considering adding a radiant barrier to your attic, consult a professional to ensure it is installed properly and to achieve the maximum benefits. That will help to keep your air conditioning running less, improve your indoor comfort, and extend the life of your HVAC system.
Using radiant barriers to keep heat out in summer and during winter can positively impact a home’s energy efficiency. However, there are other factors to consider when deciding whether or not this type of insulation is right for your house. For example, you should ensure that the existing attic insulation is in good condition and has not been compressed or displaced by installing a radiant barrier. Additionally, inspecting the attic for signs of moisture and addressing any issues is important.
One way to ensure that your radiant barrier works is to hire a professional for the job. These specialists can check for gaps or areas not properly covered, impacting how well the product works. They can also ensure that the reflective surface is properly sealed around any penetrations or vents in the attic, such as chimneys, electrical wiring, and ductwork.
Another consideration is how much you are willing to invest in a radiant barrier. In general, you can expect a 5 to 25% payback on the initial investment, depending on the amount of roof area installed with the insulation. For instance, a single-story ranch-style home will see a greater impact than a stacked two-story home with a small attic.
In addition to the cooling benefits that a radiant barrier can offer, it can also help with heating costs in the winter by reflecting heat into the living space. That can be a great benefit for homeowners who live in hot climates or those with HVAC equipment or ductwork in their unconditioned attic.