Radiant Barrier technology goes back to the 1960's and the space program. Astronauts and space craft needed it to prevent from be roasted in the intense glare of the sun during trips to the moon. Heat is conducted by one of three transmission methods. A pan on the stove gets hot by Conduction. The heat source transfers heat by direct contact. Heat is transmitted through your roof structure by hot shingles touching the roof deck. The upstairs or ceiling in your home gets hot because warm air rises. This is heat transfer by Convection. Heat is transferred from one source to another by Radiation. Radiation works as an object such as your home standing in the sunshine and soaking up the suns energy.
Radiant Barriers work by blocking the radiation transmission of heat. Aluminum foil is a great radiant barrier material because it blocks about 97% of the radiation transmission of heat. Gold works better, but we have yet found a way to economically line your home's attic with gold so we are still using aluminum.
Radiant Barriers can be applied to the roof deck, roof rafters and ceiling joist. They all require and open air to dissipate the energy collected during the reflection process. Each location has some strengths and weakness. The closer to the radiation source the better. That means the roof during the summer and the rafters during the winter. Ventilation of the attic is very important in both scenarios.
There are different material that can be used. Paints and sprays are less effective and subject to binder failure when applied. Foils can tear or collect dust that can decrease efficiency.
There are heavy duty nylon reinforced material so the barrier will last and withstand attic foot traffic. The radiant barrier can be perforated to minimize condensation from within the home during the winter months that can cause a loss of efficiency in the attic insulation.
Improvements in efficiency decrease with the amount of insulation present. This is a better option for older less insulated homes than for newer better insulated home. Reduction in energy bills can be between 10 and 30% depending on the variables.
Energy Savings Tips (EST) Newsletter