Radiant Barrier
A radiant barrier is a material with a very low emissivity and high reflectivity giving it the ability to virtually stop the transfer of radiant heat or thermal conductivity. It effectively reduces the amount of heat entering a home.
How Does it Work?
Think of a mirror. If you hold it up the sun and reflect the light on your arm. You SEE the light, but you FEEL the radiant heat.
Radiant barriers work the same way – they reflect heat away from your home.
By reducing the temperature in your attic, you reduce the amount of heat absorbed by your insulation, and therefore, the amount of heat that enters your home through the ceilings.
An attic installed radiant barrier will reduce heat gain through the ceiling by roughly 40%
Many independent studies and radiant barrier users have tested their results and reported huge savings
Here is one such independent study in which the attic temperature of two similar neighboring houses where tracked over the course of one day. As you can see from the image below, the attic with radiant barrier performed quite nicely.
R-Value
This may surprise you, but radiant barrier has NO R-Value, such as is attributed to fiberglass, cellulose or Styrofoam insulation, however with an a space of 3/4” or more, radiant barriers have a theoretical R-Value of 53.
Radiant barriers address radiant heat transfer, the single most efficient type of heat transfer, by reflecting that radiation away from the radiant barrier (as shown in the image above). A typical home heat in the summer and the majority of that heat is radiant heat, so stopping radiant heat transfer is the most effective way to reduce energy cost.
Radiant barrier reduces energy costs because it is double sided, and will reflect radiant heat away during the hot summer months. Installing a radiant barrier in your attic is the most cost effective way of reducing your cooling cost while providing the quickest payback (approximately a year) of any energy efficient material or product.
Radiant barrier can cut your cooling costs in half!
How Does the Math Stack up?
Radiant barrier installation typically costs about $0.75 per square foot of your home’s footprint. A 2000 square foot house will cost about $1500 for complete installation.
Your cooling costs account for about 70% of your power bill. For every $100 you pay to the power company, $70 is just for cooling your home.
The average power bill in Central Florida for a four bedroom home is about $150 in the winter and about $250 - $300 in the summer. 2009 was an exceptionally hot summer, so power bills of $350 - $400 were not unusual.
Your typical annual power bill is in the region of $2600. 70% - $1820 of this is for cooling your home. Installing a radiant barrier should half this amount saving you approximately $910 a year. The break-even point is less than 20 months.
