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How does Insulation Work?


The control of heat flow, that's how insulation works. Thermal insulation is designed to restrict and resist heat transfer via three mechanisms i.e. conduction, convection and radiation. Conduction is how heat moves along or through a material by effectively being passed along from one molecule to another. It can take place in solids, liquids and gasses. The ability of a material to conduct heat depends on the material. Using a low conductivity gas in insulation rather than air further helps to reduce conduction.

Convection only takes place in gases and liquids; it cannot happen in vacuum or solids. When a molecule that make up liquid or gas heat up, their densities will change. Warmer air will become less dense and rise. Closed cell insulation with small cell sizes inhibits convection within the cell, making them less prone to neighboring cells. Radiation is the process of heat transfer across space from one body to another as energy. Radiation can occur in solids, liquids, gases and even vacuum. The rate of heat transfer through radiation is controlled by the difference in temperature on the surface, the distance between these surfaces and the emissivity of the surface. Emissivity is basically how shiny the surface is, in other words it's the ability to reflect thermal radiation. A simple example would be a low emissivity foil facing on an insulation board or panel.

To summarise, heat transfer can occur through conduction, convection and radiation, thermal insulation glass wool is designed to restrict this in turn reducing the amount of heat lost or gained.