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Permalink Reply by Sean Lintow Sr on November 19, 2011 at 7:39am

All things being equal & everything being done properly (air sealing, baffles, hatches) - both work fine but cellulose will win out not because of your reasons, but the simple fact that FG R-Value drops the hotter it gets.

Granted you could argue that if it was as dense as cellulose, the convection issue would be diminished but it would not be eliminated & said convection issue is one of the biggest causes of FG's loss of R-Value. Of course once both products are saturated with heat (for better lack of a term) the game is over and it is up to the AC unit to work it's magic  

As an FYI, many FG manufacturers are using recycled materials to make the product & in either case recycled doesn't always mean better - some methods & the means required to make a product from recycled materials can use more energy & put off more by products than simply using new materials

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Permalink Reply by Matthew Redmond on November 19, 2011 at 6:34pm

Hi Isaiah, Here in upstate NY we primarily use cellulose for blowing attics and dense packing sidewalls.It's cheaper, heavier, and as you noted performs better in single family residences. The one area that fiberglass works better than cellulose is on mobile home retrofits. On mobile home belly and roof blows it's lighter and absorbs much less water vapor so it's the prefered product.

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Permalink Reply by Chris Heenan on November 25, 2011 at 2:06pm

Oh yeah, I'm a nerd. At big Orange store today and stopped to read Fiberglass blow in package.

 

And I quote

Another method of insulating your attic is our loosefill insulation. Instead of laying batts or rolls, our AttiCat^® Insulation Blowing Machine conditions the AttiCat^® Expanding Blown-In PINK^® Fiberglas^™ Insulation by fluffing it along the length of the hose, adding millions of the tiny air pockets that give the material its insulating power. Because Fiberglas^™ insulation will not settle, it will maintain the same energy-saving level over time, keeping your home comfortable for years to come.

 

Mmmm. Fiberglas the maker says will not settle.

 

Why?

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Permalink Reply by Patrick Michaelyan on November 30, 2011 at 9:34am

My experience with cellulose began when I started to participate in the state of Massachusetts' home energy programs.

 

Cellulose was mandated for attics and other spaces. Before this, I had only seen blown-in fiberglass in the new home construction industry. Well, I am glad the folks in Massachusetts mandated the use of cellulose.

 

The material is more eco-friendly, it has proven to have a slower burn rate in tests (compared to all other insulation materials), it can serve as a partial air seal, and the dust issues can be reduced with certain strategies.

 

Let me also say that I am the foreman\super on all my company's insulation jobs, and I can tell you that (with proper air sealing performed prior to installing loose-fill cellulose insulation) there is no real comparison you can make when it comes to overall effectiveness of cellulose versus fiberglass.

 

In the end, one cannot stress enough the need to perform thorough air sealing of any space you wish to install blown-in insulation for.

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