Traditional Attic Insulation Versus Radiant Barrier
Traditional insulation and Radiant Barrier. At Energy Improvements we are asked, “how does a radiant barrier different from attic insulation?” This is a great question. In order to understand the difference between Radiant Barrier and conventional attic insulation, you will need to know how hear transfers. There are three types of heat transfer
- Conduction: Conduction happens when two solid objects touch each other. Heat is transferred through the objects. A good example, is when the stove gets hot, heat gets transferred to the teapot.
- Convection: When the air is warm, warm air expands and rises.
- Radiation: Radiant heat, the movement of heat from a warm space to a cool space. A good example, a heat from a fire moving towards the colder areas surrounding the fire.
Now that we understand heat transfer let us move on to how insulation works. Insulation works with heat similar to how a sponge works with water. If we pour water into a sponge it can only hold a curtain amount of water before it begins to leak from the bottom. Insulation works by trapping air in millions of air pockets. It will slow down the heat. However, when you insulation becomes to full, then the heat will continue onto the cooler regions in your house. Traditional insulation is an important part of battling the heat transfer. The higher the R-Value the greater the insulating effectiveness.
According to the Departments of Energy, “the still air(in insulation) is an effective insulator because it eliminates convection and has low conduction.” Did you notice there is no mention of traditional insulation stopping radiant heat transfer? NASA had to deal with radiant heat in outer space where the astronauts could go from two hundred degrees below zero in the shade to two hundred degrees above in the sun. In order to protect the astronauts and the vital electronics inside the space ship they created the Radiant Barrier. Radiant barrier works off two main principles.
- Reflectivity: Heat is reflected back from where it came from. Aluminum is reflected on the hot side. The Energy Improvements Shield Radiant Barrier has 97% reflectivity.
- Emissivity: Radiant barriers work off the emissivity. Which means the amount of heat that can pass through from the hot side to the cool side. Energy Improvements Shield Radiant Barrier only allows 3% of radiant heat to pass through.
What does Radiant heat mean to you? In the summer up to 93% of heat gain is radiant heat. Even the Departments of Energy acknowledges that traditional insulation doesn’t stop radiant heat transfer. It can only stop convection and conduction. This means your air conditioner has to run longer in order to cool the excessive heat entering in your home. In the winter your house will lose up to 75% of the radiant heat. This transfer will happen and it does not matter if you have fiber glass, Rock wool, or any other style of insulation. Insulation does not stop radiant heat transfer. NASA found what stops radiant heat, and that is a Radiant Barrier.
It is also proven that a Radiant Barrier will out perform four to seven feet of conventional insulation. There is no comparison to real bottom line results.