Comparison of different types of insulating materials

Depending on your construction conditions, which insulating material is more efficient for your building? It is now possible to introduce more environmental respecting materials such as cotton and wool insulation.

Cotton insulation

Because it can be harvested annually, cotton is considered as a rapidly renewable raw material, which has environmental advantages because of its long-cycle renewable resource extraction. However, it should be noted that current cotton growing practices are very pesticide intensive, this is one of the drawback of this material. Cotton insulation is made of around 75% from post-industrial cotton such as jeans, so it is not directly associated with those agricultural practices. At the end of its useful life, cotton insulation can, in theory, be recycled. Cotton insulation consists of 85% recycled cotton and 15% plastic fibers that have been treated with borate.

Cotton insulation in batts is easy to install and comparable to fiberglass about energy-efficiency. Nevertheless, we could underline the fact that it avoids some potential health problems of fiberglass. It does not itch when it contacts skin and contains no formaldehyde or other chemical irritants. Furthermore, it is a recycled material and it requires minimal energy to manufacture.

The thermal resistance of this product is R-3.4 for 1 inch thickness. Cotton insulation has thermal properties similar to those of fiberglass. However, this R-value is idealized, as effective insulation capabilities for all types of batts can be significantly lower due to typically deficient installation because of air leak. Plus, sealing air leaks as spray or blown-in insulation, further reducing actual energy performance of the building envelope. The cost of cotton batt insulation is about $1.20 per s.f.. Cotton insulation generally costs about twice as much as fiberglass batts.

 Wool insulation

Animal’s wool, such as sheep’s wool, used as an insulating material, is now available in batts form. The cost of sheep’s wool batt insulation is approximately $2.40 per s.f. Sheep’s wool is a natural product that is sustainable. The thermal resistance of it is R-3.5 for one inch thickness.

Mineral wool insulation refers to fiberglass, rock wool (made from basalt, a volcanic rock, and limestone) and slag wool (made from blast furnace slag). It is used in batts and board form in commercial buildings for fire-resistance and acoustical advantages. Mineral wool batts are made primarily of rock wool. Rock wool for residential insulation is more common in Europe, Canada, Oceania than in the United States of America. Mineral wool provides better acoustical absorption than fiberglass and has a higher insulating value of R-3.8 for 1 inch thickness. The price is around $ 0,7 per s.f..

Comparison between those insulating materials

MATERIAL

R-VALUE

COST $/s.f.

Cotton

3,4

1,2

Sheep’s wool

3,5

2,4

Mineral wool

3,8

0,7

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