insulation

Insulation refers to materials or techniques that reduce the rate of heat transfer or sound transmission between spaces with different temperatures or acoustic properties. In buildings and equipment, insulation improves energy efficiency, comfort, and safety by slowing heat flow and dampening noise. Electrical insulation, by contrast, prevents unwanted current flow and protects people and equipment from electric shock.

Thermal insulation reduces heat transfer by limiting conduction, convection, and radiation. Its performance is commonly expressed as an R-value in the United States or RSI in metric units, representing thermal resistance. Higher R or RSI values indicate better insulation; lower U-factors indicate greater overall resistance. Insulation is used in walls, roofs, floors, ceilings, and pipes, and can also mitigate heat loss in cold climates and heat gain in hot climates.

Common insulation materials include fiberglass, mineral wool, cellulose, rigid foams (polystyrene and polyiso), spray foams, aerogel, reflective foil systems, and natural fibers such as cotton or sheep’s wool. Each material has different thermal performance, moisture behavior, fire resistance, and environmental impact. In addition to bulk insulation, reflective barriers and air gaps may be used to manage radiant heat transfer.

Installation considerations influence effectiveness. Proper thickness, fit, and avoidance of gaps reduce thermal bridging and air leakage. Vapor retarders or barriers control moisture migration in some climates, while fire ratings and permeability are important for safety. For acoustic insulation, mass and porous structure help block sound transmission.

Standards and codes often require minimum insulation levels and specify testing methods. In practice, effective insulation contributes to energy savings, comfort, and building durability, and choices depend on climate, building design, and sustainability goals.