When choosing insulation materials, thermal conductivity is an essential aspect that must be considered, particularly in construction. Among the insulation materials provided by United Insulation, rock wool and glass wool, both being types of mineral wool, have excellent thermal insulation properties. This article compares and analyzes in detail the thermal conductivity between rock wool and glass wool, enabling an informed choice in any situation.

The thermal conductivity value is an essential parameter that represents how efficiently a material can conduct heat. It is expressed in W/m·K. Lower value materials have superior insulation properties. For glass wool, made from melted glass that is spun into fibers, the value is between 0.032 and 0.040 W/m·K. For rock wool, made from volcanic rocks and slag, the value is between 0.033 and 0.045 W/m·K. In comparison, glass wool has a lower value, making it superior in insulation.

In real-life applications, like building walls, the lower λ-value of glass wool results in a reduction of heat loss by 5 to 10 percent compared to rock wool with the same thickness. Rock wool, however, is better than glass wool for use in very high temperature areas, as it can be exposed up to 1000°C, whereas glass wool can only be exposed up to 600°C, as per the thermal performance of insulation materials.

The factors that affect conductivity are density and moisture absorption. High-density rock wool, with a density of 80-200 kg/m³, offers good thermal performance, but it is expensive, whereas glass wool, with a density of 10-80 kg/m³, is easier to install. Moisture absorption, which increases conductivity by 20 to 30 percent, is better handled by rock wool, as it is given hydrophobic treatment. For better results, follow our rock wool and glass wool selection guide.

Laboratory tests show that for a thickness of 100mm, the R-value, i.e., thermal resistance, of glass wool is 3.0 to 3.5 m²K/W, whereas for rock wool, it is 2.8 to 3.2 m²K/W. For better results in energy-saving constructions, both materials can be used, with glass wool for internal and rock wool for external insulation, as per the thermal conductivity of building insulation.

Ultimately, the choice depends on project needs: glass wool for cost-effective, lightweight insulation, and rock wool for durability in harsh conditions.

FAQs:What is the main difference in thermal conductivity between rock wool and glass wool?

Glass wool generally has a slightly lower λ-value, making it more efficient for standard insulation.

How does temperature affect the thermal conductivity of these materials?

Rock wool maintains lower conductivity at higher temperatures, ideal for fire-prone areas.

Can density variations impact the comparison?

Yes, higher density improves conductivity resistance but increases weight and cost.