Soojusisoleerivus

Soojusisoleerivus is a property of materials or systems that describes how effectively they resist the transfer of heat between regions of different temperatures. In practical terms, higher soojusisoleerivus means better insulation. It is central to building science, clothing, refrigeration, and many industrial processes.

The rate of heat transfer through a material is governed by its thermal conductivity, k, measured in watts per meter kelvin (W/m·K). The lower the k, the greater the insulation. Insulation performance in a wall or other assembly is often summarized by the thermal resistance R (m^2·K/W) and the U-value (W/m^2·K) of the structure; larger R and smaller U indicate better insulation. Other related metrics include thermal diffusivity, alpha = k/(rho*c), which reflects how quickly a material responds to temperature changes.

Soojusisoleerivus depends on material properties such as porosity, density, moisture content, and microstructure, as well as thickness and installation quality. Air gaps, gaps around edges, or moisture can greatly reduce effective insulation. Materials used for high soojusisoleerivus include polystyrene (EPS/XPS), polyurethane foams, mineral wool, fiberglass, and lightweight aerogels.

Applications include building envelopes (walls, roofs, floors), refrigeration insulation, automotive and aerospace components, and thermal protection clothing. Measuring standards exist, for example with methods that determine k via steady-state or transient heat flow.

See also: thermal conductivity, R-value, U-value, thermal insulation.