FAQ

Hy-Fi® is a hybrid insulation system that combines the best of spray foam insulation and reflective insulation properties. This system defends against all forms of heat transfer at a reasonable price.

All radiant barriers are effective. The difference is in the application or installation. The two most common are the deck applied and the truss-mounted installation. They can be categorized as economy and premium. – The first installation applies the radiant barrier directly to the underside of the roof deck. This application does not allow air space between the roof deck and the radiant barrier. Also, this application loses some effectiveness each time it comes into contact with one of the roof trusses. In addition, any nails that penetrate the roof deck reduce the product’s effectiveness (shingles require a lot of nails or staples). This type of application would be considered an economy version.

Silver Shield™ Radiant Barrier is installed to cover the roof decking and the bottom of the top cord of the roof trusses. This leaves an airspace between the radiant barrier and the roof deck, which provides additional performance. In addition, the multi-layer design provides an additional layer of aluminum for maximum protection. Silver Shield™ Radiant Barrier is the best product installed using the best installation method. It is a premium radiant barrier system. – Remember, the larger the aluminum surface exposed to air, the better the performance of the radiant barrier system. The more wood and nails that are exposed, the greater the loss in performance.

Yes. The ASHRAE Handbook values are a subset of data from the National Bureau of Standards (NBS).

Deck-applied radiant barriers do not work as well as applying the radiant barrier to the bottom of the roof rafters, the way our Silver Shield™ Multi-layer Radiant Barrier is installed.

  1. Good: Deck-applied Radiant Barriers (1 airspace below the radiant barrier surface)
  2. Better: Draped over the rafters (2 airspaces: 1 airspace above and below the radiant barrier)
  3. Best: Attached to the bottom of the top cord of the roof truss or roof rafters (3 airspaces: one above, one below and one in between the layers of the multi-layer radiant barrier. This application allows for the bottom of the roof rafter to be completely covered with foil.)

In summary, you want as much of the roof deck covered with low-emittance materials (foil). Deck-applied and draped radiant barriers sandwich the foil between the top cord and the roof deck. This area will continue to radiate as if there were no radiant barrier. The total area of roof rafters (compared to the total underside of the roof surface) is as much as 35% – that’s a lot. This means that 35% of the bottom of the roof surface radiates at a high rate (82% to 90%) as opposed to the surface of the foil radiant barrier, which only radiates at 3% to 5%. Covering the roof rafters with a low-emittance radiant barrier improves the overall performance of the radiant barrier application. FI-FOIL® recommends that you use the bottom of the roof rafter application and the premium product for this application – Silver Shield™ Radiant Barrier, a multi-layer radiant barrier. Radiant barriers, like many other products, have different performance levels. However, the performance of these products is not only attributed to the product but to the application, as well. If you are going to do the job, why not insist on the best application and the best product for the application? FI-FOIL® has products for all three applications.

Condensation will occur on any surface when the surface temperature is at or below the “dew-point temperature” for an air-water mixture. The dew-point temperature depends on the dry-bulb temperature (measured with an ordinary thermometer) and the relative humidity in the space next to the surface. The dew-point temperature is less than or equal to the dry-bulb temperature. The two temperatures are equal when the relative humidity is 100%. Some examples of dew-point temperatures:

Temperature Relative Humidity Dew Point
70°F (70 Degrees Fahrenheit) 50% 50.5 1/4F
70°F (70 Degrees Fahrenheit) 75% 66.6 1/4F
70°F (70 Degrees Fahrenheit) 90% 66.9 1/4F

As you can see, condensation can occur when the outside temperature is cold. Insulation below a roof deck will have an inside surface temperature above the roof surface temperature. The actual temperature of the inside surface depends on the thermal resistance between the roof and the inside surface. The higher the resistance, the closer the interior surface temperature is to the inside air temperature. Maintaining a reasonable inside relative humidity (less than 60%) is important in preventing condensation.

A radiant barrier is a product that features a low emittance surface(s) (normally aluminum foil) that is designed to significantly reduce heat transfer between a very hot and high radiating surface (bottom of a roof deck) and a cooler, highly absorbent surface (i.e., insulation on top of a ceiling). Multiple low emittance surfaces, even multiple layers with enclosed air spaces, can further reduce radiant heat transfer. Effective emittance is one term that can quantify the impact of the additional surfaces. In summary, the lower the emittance (radiation rate), the better the performance. Radiant barriers have been demonstrated to achieve significant energy savings in various building types and multiple climate zones.

Heat radiates through the roof, and areas unprotected by the radiant barrier will allow heat to transfer to other areas of the house. Installing a radiant barrier in all areas of the house improves overall performance and increases comfort levels in unconditioned areas like garages and patios.

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Yes, but it is a lot more costly due to labor. The time to consider it is in the new construction phase. Many other energy upgrades, such as additional blown or batt insulation, can be easily added later if the current budget is a factor.

These roofs are excellent reflectors of solar reflectance when new, but the reflectivity is lowered over time as they age and get dirty. Radiant barriers would still reduce whatever heat flow penetrates the roof surfaces by the same percentage – less heat is coming through these types of metal roofing materials than a shingle roof. As the metal roof ages and the metal reflects less solar radiation, the radiant barrier has a greater impact on energy savings.

No, they work with or without ventilation but will perform better in ventilated attics. According to the building code, all attics in Florida must be vented. Extended Version: Studies have shown that with or without a radiant barrier, a ventilated attic is best and the same holds true for a radiant barrier. A house will perform better with a radiant barrier and a ventilated attic than a house with a radiant barrier and a non-ventilated attic. Houses must be designed to meet the building code, which has ventilation requirements with or without a radiant barrier. In both cases, the ventilation rate is important, not the method or type of ventilation.

As building envelopes are getting tighter, building scientists, energy centers and research organizations suggest that insulation products and facings used in hot, humid climates have higher perm ratings for increased water vapor transmission. FI-FOIL® Hi-Perm versions are designed to meet or exceed these recommendations.

Radiant barriers reduce heat gain (in the summer) and heat loss (in the winter), so it will benefit both winter and summer savings and comfort. In the summer, heat is reflected back to the outside and in the winter, heat is reflected inwards.

A water vapor retarder may or may not be part of the design depending on the climate zone and the other building components used in that particular section of the building envelope. If air containing water vapor is allowed to come in contact with a cold surface, condensation will likely occur. Water vapor transmission can also occur even if the building envelope is air-sealed or has an effective and properly installed air barrier. Some insulation systems should include a water vapor retarder and some should allow vapor transmission. Building codes and climate zones generally dictate the use of a water vapor retarder. In short, the envelope is a system, and the building designer should carefully consider its use.

Various studies, including those conducted by the Florida Solar Energy Center, have concluded that it would be highly unlikely. In the Sunbelt and specifically Florida, shingles are exposed to 160 to 190 degrees roof temperatures. Studies have proven that radiant barriers only increase roof temperatures by 2 – 5 degrees. A few degrees more won’t make a difference.

To best increase your energy efficiency, you should deal with the problem at its source, the roof, and the best way to address it is by adding a radiant barrier. A radiant barrier is specifically designed for this application and will reduce heat transfer by up to 97%. The radiant barrier will improve the air conditioning ductwork and the mass insulation performance. It will improve comfort in garages and patios, typically not conditioned areas.

Studies have shown that the radiant barrier/mass insulation combination outperforms mass insulation alone. Silver Shield™ radiant barrier is installed just below the roof sheathing. The idea is to stop the heat at the source, the roof, before it gets into the attic or building envelope.

Standard mass insulation is almost always installed on the surface of the ceiling, and air conditioning duct systems are almost always installed in the attic space. So, without a radiant barrier, the heat would build up in the attic and reach extreme temperatures upwards of 140 degrees.

Think about it: does it make sense to pump 55-degree air through ducts running through a super-heated attic? And does it make sense to expose insulation to extreme temperatures when the R-value rating is determined at 75 degrees, with the knowledge that the R-value rating drops as the temperature increases? No, of course not! Why let the heat get in the attic in the first place?

To summarize, adding a radiant barrier simply provides more benefits over adding more insulation (cooler attic, improvement in duct performance, improvement in ceiling insulation performance, and more comfortable home areas that are typically not insulated, like the garage and patio). If you have extra money in your energy budget, do both; however, the order is radiant barrier first, more ceiling insulation second.

R-values relate more to mass-type insulations or insulating materials that are installed in an enclosed air space. Radiant barriers are typically designed to work in vented attics, so their performance is not rated with an R-value; however, R-values are not the ONLY way to quantify resistance to heat flow. For example, a tree or an awning doesn’t have an R-value, but it certainly can keep you cool. Simply put, a radiant barrier is like putting a shade tree in your attic. Technically speaking, Silver Shield™ Radiant Barrier reflects 97% of the radiant heat and only emits 3% into the attic, so unlike the R-value, the lower the “E-value,” or the less that it radiates into the attic, the better the radiant barrier. Silver Shield™ is the best-rated radiant barrier on the market.

A reflective insulation below the roof deck results in an interior surface temperature that is greater than the outside temperature (in cold weather). As the inside surface temperature increases, the conditions for condensation become less likely to occur.

Reflective insulation has little effect on heat transfer by conduction through the air between hot and cold surfaces. Air with an R-per-inch of 5.6 is an excellent insulator for controlling radiation and convection. Installing reflective insulation in an enclosed space reduces thermal radiation to near zero. When the reflective insulation is installed to subdivide an air-filled region, convection is also reduced.

Reflective insulation is one or more low-emittance surfaces installed in an enclosed air space. The more layers within the air space, the better the performance.

Reflective insulation in a wall system can be compared to a double or triple-pane window with low-e surfaces. Triple pane windows with low-e surfaces perform better than triple pane windows without low-e surfaces because of the reduction of radiation (low emittance) across the air spaces. Air inherently has an R-per-inch value of 5.6 and is an excellent insulator when radiation and convection are controlled.

The ASHRAE Handbook has tables with values for various enclosed air spaces (0.5″, 0.75″, 1.5″, 3.5″, etc.) with high emittance surfaces (0.82 for common building materials) and values for air spaces with low emittance surfaces facing the enclosed air space (0.05 for low emittance materials like aluminum). Adding a low e material makes the enclosed air space perform better.

A multilayer reflective insulation system in a wall cavity improves this system by further reducing radiant heat transfer and adding additional “panes.” a two-layer reflective insulation could be compared to a double-paned window, a three-layer to a triple pane window, and so on.

The installation of reflective insulation in an enclosed space reduces thermal radiation to near zero. When the reflective insulation is installed to subdivide an air-filled region, heat transfer by convection is also reduced.

FI-FOIL® has single-layer, two-layer, three-layer and even honey-comb layer reflective insulation products for various building applications, each with different performance levels and attributes for the particular application. These products also work very well with other types of mass insulation as hybrid systems by using the best attributes of each of the technologies (e.g., spray foam is great for air sealing and can have a high R-value per inch of thickness — fiberglass and cellulose is an inexpensive material to reduce convection in the cavity). In some wall systems, especially wall cavities larger than 1.5″, a combination of reflective insulation with one or more of these mass insulation products addresses all the modes of heat transfer — often more cost-effectively than one of the technologies used alone.

The R-value for a reflective air space depends on the temperature difference across that air space. The temperature across the air space depends on the R-values in the system since the bounding temperatures are fixed.

30 minutes is the best waiting period before installing Hy-Fi®. As the spray foam cures, moisture is released through an exothermic reaction (looks like steam). It is best to allow this moisture to escape before installing a Hy-Fi®.

The “tested” value is for specific dimensions – specifically the air space between the Hy-Fi and foam. The tested precision is about +/- 10%. Because of this, the agreement between the calculated and “tested” values is quite good. Hy-Fi® adds R-7.1 to the insulation assembly with a 1.5″ air space

The Problem with No Radiant Barrier

In homes lacking a radiant barrier at the roofline, the roof absorbs solar heat, which significantly raises attic temperatures, sometimes exceeding 150 degrees Fahrenheit. This intense heat has several detrimental effects on your home’s energy efficiency and comfort.

Impact on Attic and Insulation

Elevated attic temperatures can lead to increased heat gain in air conditioning ducts and diminish the effectiveness of mass insulation. It’s crucial to note that the R-values of mass insulation, which measure its resistance to heat flow, are determined at a standard temperature of 75 degrees Fahrenheit. Any increase in temperature can reduce these values, thereby compromising the insulation’s efficiency.

Building Materials and Stored Heat

The extreme temperatures not only affect air conditioning and insulation but also saturate the building materials in your attic. These materials can store heat, acting as a heat sink, and continue to transfer heat into your home’s living area even after the sun sets. This results in the air conditioning system running for longer periods, consuming more electricity, and leading to higher energy bills.

Solution: The Radiant Barrier

Installing a radiant barrier presents a highly effective solution. It can block up to 97% of radiant heat transfer, significantly improving the performance of insulation materials and reducing attic temperatures by as much as 30 degrees Fahrenheit. With a cooler attic, less heat is transferred into your air conditioning ducts.

By lowering attic temperatures and enhancing the efficiency of your insulation, radiant barriers contribute to reduced cooling and heating costs. This not only leads to immediate savings on energy expenditures but also promotes a more comfortable and energy-efficient living environment throughout the year.

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