lämpökestävyyys

Lämpökestävyys, or thermal resistance, is a property of a material that describes its ability to resist the flow of heat. It is the inverse of thermal conductivity. A material with high thermal resistance will prevent heat from passing through it easily, while a material with low thermal resistance will allow heat to pass through more readily. This property is crucial in many applications, particularly in building insulation, where high thermal resistance is desired to reduce heat loss in winter and heat gain in summer.

The thermal resistance of a material is typically measured in units of Kelvin-meters squared per watt (K·m²/W) or degrees Celsius-meters squared per watt (°C·m²/W). For a single layer of material, thermal resistance is calculated by dividing the thickness of the material by its thermal conductivity. For composite structures, such as walls or windows, the total thermal resistance is the sum of the thermal resistances of each individual layer.

Factors that influence a material's thermal resistance include its composition, density, and moisture content. Porous materials with trapped air, like fiberglass or foam, generally have high thermal resistance because air is a poor conductor of heat. Denser materials, such as metals, tend to have low thermal resistance. Moisture can significantly reduce thermal resistance by increasing heat transfer through conduction. Understanding and measuring thermal resistance is essential for energy efficiency in buildings, designing thermal management systems for electronics, and developing protective gear.