Attic Insulation & Green Energy Barriers Work Together In All Climates
To start, using a green energy barrier is not a substitute for traditional types of insulation (fiberglass, cellulose, etc.). Radiant Barriers and regular attic insulation work TOGETHER to make your home more comfortable and energy efficient.
How it Helps in Hot Climates
Regular attic insulation slows conductive heat, while green energy barriers reflect radiant heat. Your home gets a lot of both and how much heat that flows in or out is determined by basically three things:
- inside surface temperatures
- outside surface temperatures
- R-value and thickness of what is between the inner and outer surfaces
The walls and top of your home are typically insulated with traditional insulation that works to slow conductive heat gain. Regular insulation slows heat, but it also HOLDS heat. At the end of a hot-sunny day, the insulation in your attic can become a big, thick 130º blanket over the top of your home. When the sun goes down, this hot blanket in effect continues to hold and drive heat into the home. Once the roof cools down, the insulation can easily be the hottest part of your whole house; this can make your air conditioner run later into the night. Adding a radiant barrier acts like a car sunshade and blocks the heat from entering the attic space so the surface temperatures are reduced and the insulation stays at a comfortable temperature. This is how installing a radiant barrier will make what insulation you already have even more effective.
By combining good attic insulation and radiant barrier, you will get the best of both properties. Reduction of conductive heat flow AND reduction of radiant heat flow by decreasing surface temperatures of the attic insulation. Lower surface temperature is like putting the house in the shade.
How it Helps in Cold Climates
The top of the insulation is wide open and exposed to air currents. Think of this like a winter jackets that has an inner layer and an outer shell that is windproof. If you take off the outer windproof shell and walk outside on a cold windy day, you will freeze your backside off.
Inside the attic, there can be a huge differential between the temperature inside the home and the attic. For example, if the attic is 20º and the living space is 70º you have a 50º difference. This large difference promotes a phenomenon called Convective Looping. This happens when cold, dense and heavy air falls through the insulation and displaces the warm air against the living space.
Installing foil on top of the insulation acts like the outer windproof shell of a jacket; it helps minimize the convective looping within the insulation while still allowing moisture to pass through the perforations.
The other reason radiant barrier foil helps in cold climates is the reduction of radiant heat loss from the living space. It’s like when you wrap a potato with foil to keep it warm. The potato will not “emit” as much radiant heat. This is called emissivity, or the prohibiting of heat release. Green energy radiant barrier AtticFoil has an emissivity rating of .03, meaning it will ONLY release 3% of the radiant energy/heat. This is why so many customers report a noticeable difference in comfort and fewer problems with rooms being hot and cold.
So, for most homes I recommend both topping off your existing insulation AND adding a green energy barrier (AtticFoil). They will work together for maximum comfort and energy savings year round.
Read More:
attic insulation, radiant barrier
March 31st, 2011 at 7:51 pm
Live in Falls City Nebraska. Bought an older house (late 60′s), one story and basement. New roof as they had never installed sauffett and there was little air getting out of vents.
I’m putting sauffets in and a fan that is heat and humidity activated.
As I am ready to retire, I want a very low energy bill.
I am a do it yourself person. I am planning to put in insulation in May (Other projects). Currently there is an insulation that is like blown paper about 6 inches deep.
Would it help to have a radiant barier??
How much blown insulation or rolled insulation would you recommend??
Rolled or blown in
Thanks Doug Williams
April 12th, 2011 at 12:40 pm
If you are DIY kind of guy and energy savings are a priority for you, then I’d recommend installing a radiant barrier in addition to your traditional insulation. Proper ventilation is an important factor in reducing the heat load of the home. The actual air temperature in an attic is mostly determined by attic ventilation. The more air, the closer the AIR temp inside your attic will get to “outside” air temp (also known as ambient temperature). Then, in addition to lowering the attic AIR temperature, you also want to lower the SURFACE temperatures in your attic – this is where a green energy barrier comes in. A product like AtticFoil will block 97% of the radiant heat from entering your insulation, and ultimately your home. These two additions (proper cycle of ventilation and a radiant barrier) will not only dramatically improve the temperature of your attic, they will improve the overall heat load on your HOME which results in energy savings and a more comfortable living space.
Typically the type of insulation you use doesn’t really matter – just so long as it’s up to standard. As for the amount of insulation, the recommended amount for Nebraska is between R25 and R60 for that area of the US. Check out this insulation recommendation map put out by the government on what they suggest: Recommended Levels of Insulation on Existing Buildings
June 9th, 2011 at 6:13 pm
I always advise the use of insulation with radiant barrier foil to keep heating and cooling costs low. Many problems that are often mistakenly attributed to the roof itself are actually due to poor insulation.