Cellulose vs Fiberglass

While fiberglass may be the most common type of insulation, it is definitely not the most effective. Here are the facts:

While there may be a lot of bad information and outright lies about various insulation materials available today, we thought you should know some facts so that you can make the right decision for your home and family.   Insulation is rated in R-values; the higher the R-value, the more effective the insulator is....sort of. You see, there is more to insulation than just R-values. The job of insulation is to block heat transfer: to keep heat out in the summer, and keep it in during the winter. Heat can be transfered 3 different ways: through convection, conduction, and radiated heat. R-values only measure heat transfer through conduction. So two different materials can have the same R-rating, yet perform completely different. What you want as a consumer is an insulator that effectively blocks all three methods of heat transfer. Fiberglass has it's shortcomings in regards to it's thermal performance, especially compared to our cellulose insulation. Fiberglass insulation can lose up to 50% of its rated R-value in extreme temperatures! Even NAIMA (North American Insulation Manufacturers), a group of fiberglass manufacturers, states in it's Insulation Facts #35 booklet : "..some light density loose-fill fiberglass products then may see a reduction in thermal performance..." when attic temperatures change. What does this mean to you as a consumer? Basically it means that when you need it most, in the heat of summer and in the cold of winter, fiberglass insulation does not perform as well as it's rated. *************************************************************************************************************** The University of Colorado School of Architecture and Planning built two identical structures in the winter of '89-'90. One was insulated with fiberglass, the other with cellulose. They tested both units and found that in addition to using over 25% less energy than the fiberglass unit, the cellulose structure stayed warmer during a nine-hour heat loss test...even though both attics were rated at the same R-value. They concluded that the cellulose insulation was approximately 38% more effective than the fiberglass!! In addition to being a poor insulator, fiberglass has some health risk associated with it, also. I'm sure you are familiar with the itching and skin irritation that fiberglass can cause. This is because the tiny strands and fibers that make up the insulation can break apart very easily and wind up in your skin and in the air. What happens when it gets in the air and you breathe it? Well, it goes in your lungs...and stays there. Fiberglass also happens to be listed on the National Toxicology Program's report on carcinogens as being "reasonably anticipated to cause cancer in humans". *************************************************************************************************************** Cellulose insulation offers more thermal performance than fiberglass, without the health risks associated with fiberglass. You see, unlike fiberglass insulation, cellulose does not suffer the same reduction in thermal performance when the temperatures change significantly. So in the summer and winter, you get the insulation performance you paid for. The main reason for cellulose's superior insulating properties is because it effectively controls all three ways heat can be transfered. Heat transfer through air (convection) is a key factor and cellulose is superior to fiberglass in this respect: hot air in the attic goes through the fiberglass and begins to penetrate through your ceiling. But with an attic insulated with cellulose, a significantly higher percentage of the heat stays in the attic because of it's resistance to heat flow by convection. When it comes to Cellulose VS Fiberglass...Cellulose wins hands down!

Cellulose vs. Fiberglass

The NRDC has concluded the following:

• Cellulose insulation manufactured from recycled paper is the least polluting and most energy efficient insulation.

• Cellulose has the highest post-consumer recycled content. The fiberglass industry averages 35% recycled glass, while the cellulose industry averages a minimum of 75% recycled content.

• It takes more than 10 times as much energy to produce fiberglass insulation as cellulose insulation.

• Due to air circulation and natural convection, the R-value of blown-in fiberglass insulation decreases by as much as 50% as the temperature drops from 45 degrees F to 18 degrees F.

• Cellulose has better resistance to air flow and prevents the upward movement of air caused by temperature differences (the R-value of cellulose actually improves during cold weather).

• Substantial and well-documented public health threats are associated with fiberglass.

• No adverse health effects from cellulose insulation have been identified.

• Cellulose that has been properly installed in your walls will not settle.

• Cellulose is non-corrosive to steel, copper and aluminum.

• Cellulose will not lose it's energy saving abilities over time.

• Cellulose will not rot, decay or mildew, and it does not support fungus or mold growth.