Calcium silicate bonded with sodium silicate. Although it is popularly considered an asbestos substitute, early uses of calcium silicate for insulation still made use of asbestos fibers. It is used in passive fire protection and fireproofing as calcium silicate brick or in roof tiles. It is one of the most successful materials in fireproofing in Europe because of regulations and fire safety guidelines for commercial and residential building codes (see Calcium Silicate use in Europe). Where North Americans use spray fireproofing plasters, Europeans are more likely to use cladding made of calcium silicate. High-performance calcium-silicate boards retain their excellent dimensional stability even
Thermal insulation commonly used. For some materials, thermal conductivity may also depend upon the direction of heat transfer. The act of insulation is accomplished by encasing an object with material of low thermal conductivity in high thickness. Decreasing the exposed surface area could also lower heat transfer, but this quantity is usually fixed by the geometry of the object to be insulated. Multi-layer insulation is used where radiative loss dominates, or when the user is restricted in volume and weight of the insulation (e.g. Emergency Blanket, radiant barrier) For insulated cylinders, a "critical radius" must be reached. Before the critical radius is