Mills Efficient Home

A radiant barrier is a highly reflective material applied to the underside of your roof that is designed to reduce summer heat gain and winter heat loss in your home.

A radiant barrier works in concert with attic insulation and balanced ventilation to keep your home comfortable and your energy bills in check.  The two most common types are radiant barrier spray, also called radiant barrier paint, and radiant barrier foil.  Mills uses only the best radiant barrier paints that are tested and certified to block the most heat.  We are proud to install the new and improved Sherwin Williams radiant barrier as well as HeatBloc Ultra and Radiance.  Foil radiant barrier reflects more heat but is difficult to install in tight spaces or in attics that are already well insulated.  Radiant barrier spray helps this problem because it is somewhat easier to apply, especially in tight attics because it is applied with special equipment that helps in hard to reach areas.  Because of the relative ease of application, radiant barrier paint is often more cost-effective than the foil type heat barrier.  Whichever type you choose to install, our radiant barrier installers will apply it correctly so you realize the maximum benefit from the product.  Choose your radiant barrier company wisely as some contractors will cut corners to save money.  There are even reports of contractors watering down their radiant barrier paint to “stretch” the material further.  This is something Mills would never allow.

More on the properties of radiant barriers:

When the sun heats a roof, it’s primarily the sun’s radiant energy that makes the roof hot. A large portion of this heat travels by conduction through the roofing materials to the attic side of the roof. The hot roof material then radiates its gained heat energy onto the cooler attic surfaces, including the air ducts and the attic floor. A radiant barrier reduces the radiant heat transfer from the underside of the roof to the other surfaces in the attic.

Performance is determined by three factors:

• Emissivity (or emittance) - the ratio of the radiant energy (heat) leaving (being emitted by) a surface to that of a black body at the same temperature and with the same area. It’s expressed as a number a between 0 and 1. The higher the number, the greater the emitted radiation.
• Reflectivity (or reflectance) - a measure of how much radiant heat is reflected by a material. It’s also expressed as a number between 0 and 1 (sometimes, it is given as a percentage between 0 and 100%). The higher the number, the greater the reflectivity.
• The angle the incident radiation strikes the surface-a right angle (perpendicular) usually works best.

All radiant barriers must have a low emissivity (0.1 or less) and high reflectivity (0.9 or more). From one brand to another, the reflectivity and emissivity are usually so similar that it makes little difference as far as thermal performance. (Most products have emissivities of 0.03-0.05, which generally corresponds to a reflectivity of 95%-97%.) Also, the greater the temperature difference between the sides of the radiant barrier material, the greater the benefits it can offer.

Radiant barriers are more effective in hot climates than in cool climates, especially when cooling air ducts are located in the attic. They can lower cooling costs between 10% when used in a warm, sunny climate. The reduced heat gain may even allow for a smaller air conditioning system.