Expert Advice on Green Buildings

CSR Building Materials Rockwool Insulation

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CSR Building Materials (“CSR”), an internationally diversified manufacturing company with operations throughout Asia, Australia and New Zealand, worked with (“Green-Buildings”) to complete a review of their rockwool insulation products.

CSR manufactures a range of rockwool-based insulation products including blankets, batts and pipe insulation. For the purposes hereof, specific focus has been placed on products with densities from 40 kg/m3 – 150 kg/m3.

Green-Buildings’ team of LEED Accredited Professionals determined that CSR’s rockwool insulation products may:

1. Increase Building Durability
2. Reduce Demand for Raw Materials
3. Conserve Energy and Electricity
4. Improve Indoor Environmental Quality

Green-Buildings believes that the aforementioned characteristics of CSR’s rockwool insulation products are applicable to high-performance building and also may contribute meaningfully to green building projects that pursue a LEED® Certification.

Green Building Details

Rockwool (also known as stonewool) is a type of naturally occurring fibrous mineral formation that is a byproduct of volcanic activity. Rockwool fibers may be manufactured on an industrial level by melting and spinning basalt and dolomite into thin strands which are then treated and molded for various uses, such as insulation.

A. Increase Building Durability

A key green building principle is the reduction of waste through improving building quality and increased durability. Often, the greenest buildings are those that do not need to be replaced. As such, building products that help extend the life of buildings through more durable design may eliminate the need for replacement, thereby reducing future downstream waste.

Because rockwool insulation is made from rock that is spun into fibers, it is extremely durable. When properly installed, CSR’s rockwool insulation products are capable of maintaining their initial physical characteristics throughout the life of the buildings in which they are used.

CSR’s rockwool insulation is also non-combustible. Indeed, because the insulation fibers have melting temperatures in excess of 1400-1600º C, they are often utilized in fire prevention. As such, choosing CSR rockwool over a conventional fiberglass insulation product may provide the incremental benefit of fire-resistance and improved life-safety in buildings in which they are used.

CSR’s rockwool is water-repellent and allows for reduced probability that deterioration may occur if moisture is controlled to a building’s envelope. CSR’s rockwool insulation do not support mold, mildew and/or fungus, which can further weaken interior building elements and/or require materials replacement.

B.Reduce Demand for Raw Materials

By incorporating recycled content into building materials, green builders may not only reduce the impact that results from the extraction and processing of raw materials, but also reduce the volume of solid waste that is produced as a byproduct of our built environment. CSR’s rockwool insulation products contain an average of 7.5% post-industrial recycled content.

C. Conserve Energy and Electricity

According to the U.S. Department of Energy, buildings are responsible for approximately 39% of the energy consumed in the United States. It is estimated that a significant portion of this energy use would be unnecessary if all buildings were properly insulated.

Rock wool insulation provides excellent thermal resistance and can play a significant role in reducing the energy used in heating and cooling residential and commercial buildings. By reducing the transfer of heat (and cold) through a building’s envelope, CSR’s rockwool insulation not only helps to minimize the amount of energy needed to heat and cool a building, but also reduces the greenhouse gas (GHG) emissions, such as CO2, commonly produced by coal-fired power plants.

TUV testing services conducted independent thermal conductivity tests for three samples of CSR rockwool (with varying densities). Results are as follows:

CSR’s rockwool insulation products proved to be highly energy-efficient. As can be seen above, when compared to the thermal conductivity results of typical insulation materials (0.035 - 0.16 W/m°K), CSR’s products provide low thermal conductivity, meaning they are highly effective in terms of reducing heat transfer. CSR rockwool thermal conductivity is less than 0.04 W/m°K for all products evaluated.

D. Enhance Indoor Environmental Quality

Good indoor air quality enhances occupant health and comfort and is an essential goal for any green building. The U.S. Environmental Protection Agency (“EPA”) estimates that indoor pollution levels may be two to five times (and potentially up to one hundred times) greater than outdoor pollution levels.

Potential threats to indoor environmental quality include the presence of hazardous chemicals, high concentrations of airborne fibers, and smoke, mildew, mold and/or fungus contamination.

Rockwool contains no asbestos or chemical additives. Neither the raw materials used in manufacturing nor the finished product contain any ozone depleting chemicals. Also, CSR’s rockwool insulation products are not classified as, nor do they contain, hazardous air pollutants. While phenol-formaldehyde is present in the manufacturing process, aspects of the process itself, such as high temperature heat curing and an inherent chemical reaction, eliminate all free formaldehyde from the final insulation product.

While the Occupational Safety and Health Administration (OSHA) has established the Permissible Exposure Limit (PEL) for airborne fibers as 0.10f/cc, and the U.S. EPA has established the clearance level of less than 0.01f/cc for re-occupancy, once rock wool products are installed, no significant fiber release occurs. Indeed, the majority of airborne fiber levels in buildings containing one or more rock and/or slag wool products are very low, generally less than 0.001 fibers per cubic centimeter (f/cc).

Rockwool fibers and particles are amorphous (non-crystalline). The resin and solvent refined mineral oils bind the fibers and particles together and minimize the release of dust. The cured resin is stable and will remain intact for the life of the product under normal atmospheric conditions.

LEED Scoring and Certification

To earn certification under the Leadership in Energy and Environmental Design (LEED®) rating system, projects must not only satisfy all LEED system prerequisites, but also earn a minimum number of points. Projects may earn a range of sequentially higher LEED certification ratings as determined by their compliance, as well as exemplary performance, in the credit categories within each system.

Green Buildings believes that CSR’s rockwool insulation products may contribute materially toward earning points in a LEED certification in the following prerequisite(s) and/or credit(s)1:

EA Prerequisite 2: Minimum Energy Performance (Building Design + Construction)
CSR’s rockwool insulation minimizes the energy required to heat and cool a building.

EA Credit 1: Optimize Energy Performance (Building Design + Construction)
CSR’s rockwool insulation minimizes the energy required to heat and cool a building.

MR Credit 4: Recycled Content
CSR’s rockwool insulation contains pre-consumer recycled content


CSR’s rockwool insulation products meet four significant criteria used in green building initiatives. Through its water repellent nature, heat resistant and non-combustible material qualities, rockwool insulation can improve building durability. Additionally, rockwool insulation may be effectively used to maximize energy efficiency, and minimize heat and/or cooling loss, as a function of its low thermal-conductivity. Finally, CSR’s rockwool products contain 7.5% pre-consumer recycled content, on average, contain no free formaldehyde and may have contaminant levels which fall below U.S. EPA, OSHA and LEED thresholds, thereby being potentially helpful in enhancing indoor air quality.

Product Reviewed by: Sarah Gudeman, LEED AP BD+C & Rob Freeman, Jr., LEED AP

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