Do you know what the main functions of thermal insulation are?

Thermal insulation is defined as the set of installation materials and techniques applied to a hot element or space to minimize heat transmission to other adjacent elements. There are many situations where it is advisable to reduce heat flow in a given direction. The most common case is the insulation of buildings to minimize heat loss in winter and heat gain in summer, although there are many other cases like insulation of cold chambers or distribution pipes of hot or cold liquids. The use of thermal insulation is particularly relevant when covering the ducts of a dual-flow ventilation system. During the summer, once the heat is extracted from the air introduced through the supply ducts, they must be adequately insulated so that the air circulating through them remains cold until it reaches the supply outlets. The thermal insulation of the ducts serves the same function in winter, but in this season of the year, it prevents the heat of the air introduced into the house through the heat exchanger, from transmitting to the environment and maintains the injected air at 19ºC until it reaches the supply outlets.

 

Types of thermal insulation

• Fibrous: composed of filaments with small or low-quality particles. They are placed as filling in openings or as coverings in the form of boards or blankets. They have a very high porosity of around 90%. They are used depending on temperature: fiberglass for temperatures up to 200ºC, mineral wool up to 700ºC, and alumina or silica fibers between 700 and 1700ºC.
• Cellular: are materials formed in closed or open cells, generally forming rigid or flexible boards, although they can also be shaped on-site by spraying or pouring. Their advantages include low density, low heating capacity, and acceptable compressive strength. The most commonly used are polyurethane and expanded polyethylene.
• Granular: are small particles of agglomerated inorganic materials such as perlite and vermiculite.

Properties of thermal insulators

Conductivity: expressed in W/(m.k), refers to the dry insulating material since it is a property that varies with humidity and temperature.

Permeability: expressed in g/(m.s.Pa)

Apparent density: expressed in kg/m3

Heat capacity: is used to evaluate the behavior of the insulator over a period of time

Mechanical properties: resistance to compression, resistance to bending, and thermal expansion coefficient

Water absorption: can be expressed as % volume of water per volume of material. It is very important because it can alter other values such as conductivity, density, and heat capacity