Thermal insulating materials
Contenido
Existen muchos tipos de aislante térmico, alguno de los cuales se ha abandonado a lo largo de la historia. son materiales usados que se caracterizan por su alta resistencia térmica.
Aluminum
Although aluminum is a metal with high thermal conductivity (λ= 204 W/m·°C), it can be used as an insulator under certain conditions. Aluminum insulators consist of several thin layers joined together by other folded sheets, forming something similar to lightened cardboard. Thermal losses can be due to a change of state (evaporation), by contact (or convection) or by radiation (which grows with the fourth power of the temperature difference), the aluminum managing to reflect, and thus reduce, by 97% the losses due to thermal radiation (both to cool, protecting from the sun, and from the cold, to conserve internal heat), this property being independent of the thickness of the aluminum layer. In addition, aluminum offers another advantage, being completely watertight/impermeable, and preventing the passage of water and air, thus blocking losses due to evaporation. The folding of the sheets is responsible for limiting convection.
Cork
It is the oldest material used for insulation. It comes from the bark of the cork oak. It is normally used in the form of agglomerates, forming panels. Typically, these panels are made from crushed cork and boiled at high temperatures. In general, it is not necessary to add any binder to compact the panels.
Its water content is less than 8%, and it is composed of 45% suberin. These two conditions make it a rot-proof product, which does not have to be treated to protect it from fungi or microorganisms, unlike wood.
Another advantage over other insulating materials is the high thermal inertia it presents. This characteristic makes it an ideal material for external thermal insulation systems.
53% of world cork production comes from Portugal, and 32% from Spain.
Use options according to DIN 4108-10..
• - Density: 110 kg/m³ normal, 100-160 (in plate), 65-150 (from the tree).
• - Thermal conductivity coefficient: 0.039 W/(m·K) (according to EN 13170 - 0.04 to 0.055).
• - μ (resistivity to the passage of water vapor) - 30 to 75 (of the tree), 92 MN·s/g·m (on agglomerated plate).
• - c (specific heat) from 1600 to 1800.
Cotton
This is paper from a cotton blanket.
• - Density: 25-40 kg/m³ (blown wool), 20-60 kg/m³ (blanket wool).
• - Thermal conductivity coefficient: 0.04 W/(m·K).
• - μ - 1 to 2 MN·s/g·m.
• - c (specific heat) approximately 840 J/(kg·K).
Arlita
Arlite is a ceramic aggregate that is very light due to its porosity.
• - Density: 300-800 kg/m³ (apparent density).
• - Thermal conductivity coefficient: 0.08 W/(m·K).
• - μ = 0 MN·s/g·m.
• - c (specific heat) approximately 1100 J/(kg·K).
Vermiculite
Vermiculite is a mineral formed by iron or magnesium silicates, from the mica group; During its manufacturing its temperature is rapidly raised, expanding up to 30 times its size, through a process called "exfoliation".
• - Density: It ranges between 60 and 140 kg/m³, depending on granulometries.
• - Thermal conductivity coefficient: 0.053 kcal/h/m °C.
• - Acoustic insulation: when sound waves hit the multidirectional lamellae of the expanded vermiculite, they are reflected in a multitude of directions and absorbed by the microscopic structure of air bubbles of the mineral. For these reasons, vermiculite is an excellent acoustic insulator for a very wide range of frequencies.
• - Fire resistance: the melting point of vermiculite is 1,370 °C and the softening temperature is 1,250 °C. It is a non-combustible mineral and chemically very stable at high temperatures, which makes it an ideal material for protection against fire, which is why it is mainly used as an insulator in high-temperature ovens and boilers in the form of a sheet of different thicknesses (agglomerated with resins).
• - Unalterability: vermiculite is insensitive to atmospheric agents and the passage of time. It is stable, chemically neutral (pH = 7.2) and inert, it is not hygroscopic and does not produce any action on iron or steel.
wheat husks
• - Density: 90 kg/m³ (pressed).
• - Thermal conductivity coefficient: 0.06 W/(m·K).
• - μ - 1 to 2 MN·s/g·m.
• - c (specific heat) approximately - J/(kg·K).
Linen
• - Density: 40-50 kg/m³ (raw material), 20-40 kg/m³ (blanket).
• - Thermal conductivity coefficient: 0.04-0.05 W/(m·K).
• - μ - 1 to 2 MN·s/g·m.
• - c (specific heat) approximately 1500 J/(kg·K).
Cereal pellets
Made from cereals (in German - Getreidegranulat).
• - Density: 105-115 kg/m³ (apparent density).
• - Thermal conductivity coefficient: 0.05 W/(m·K).
• - μ - 1 MN·s/g·m.
• - c (specific heat) approximately - J/(kg·K).
Hemp
• - Density: 150 kg/m³ (scratches), 20-40 kg/m³ (blanket).
• - Thermal conductivity coefficient: 0.04-0.08 W/(m·K).
• - μ - 1 to 2 MN·s/g·m.
• - c (specific heat) approximately 1500 J/(kg·K).
wood chips
• - Density: 70 kg/m³ (apparent density).
• - Thermal conductivity coefficient: 0.045 W/(m·K).
• - μ - 2 MN·s/g·m.
• - c (specific heat) approximately - J/(kg·K).
Cellulose
It is ground recycled newspaper, to which borax salts have been added to give it fireproof, insecticidal and antifungal properties.
It is blown into the chambers or projected wet. It is a powerful summer and winter insulator, and also has acoustic insulation properties. Its greatest advantage is that it behaves like wood, balancing temperature peaks while having a large thermal storage capacity, it behaves countercyclically for 12 hours, thus maintaining morning coolness in summer during the afternoons. In winter it protects against the cold in a similar way to how wood does.
• - Density: 30-60 kg/m³ (or according to other sources, from 25 to 90 kg/m³).
• - Thermal conductivity coefficient: 0.039 W/(m·K).
• - μ - 1 to 2 MN·s/g·m.
• - c (specific heat) approximately 1900 J/(kg·K).
wood fiber
According to EN 13171. Use options according to DIN 4108-10.
• - Density: 30-60 kg/m³ (blown), 130-250 kg/m³ (blanket).
• - Thermal conductivity coefficient: 0.04-0.06 W/(m·K).
• - μ - 5 to 10 MN·s/g·m.
• - c (specific heat) approximately 1600-2100 J/(kg·K).
wood wool
According to EN 13168, usage options according to DIN 4108-10.
• - Density: 350-600 kg/m³ (normal), 60-300 kg/m³ (multiple layers).
• - Thermal conductivity coefficient: 0.09-0.1 W/(m·K).
• - μ - 2 to 5 MN·s/g·m.
• - c (specific heat) approximately 2100 J/(kg·K).
Coconuts
• - Density: 70-110 kg/m³.
• - Thermal conductivity coefficient: 0.045-0.05 W/(m·K).
• - μ - 1 to 2 MN·s/g·m.
• - c (specific heat) approximately 1500 J/(kg·K).
White hair
(There are currently no cane-based products approved for use in Germany).
• - Density: 190-220 kg/m³ (scratches), 20-40 kg/m³ (blanket).
• - Thermal conductivity coefficient: 0.045-0.065 W/(m·K).
• - μ - 2 MN·s/g·m.
• - c (specific heat) approximately 1300 J/(kg·K).
algae
Used on roofs and walls.
• - Density: 70-80 kg/m³.
• - Thermal conductivity coefficient: 0.045 W/(m·K).
• - mu -.
• - c (specific heat) approximately 2000 J/(kg·K).
Straw
• - Density: 80 to 600 kg/m³.
• - Thermal conductivity coefficient: 0.045-0.13 W/(m·K).
• - mu - 1 to 10 (pressed from 35 to 40).
• - c (specific heat) approximately - J/(kg·K).
Grass
• - Density: 25 to 65 kg/m³.
• - Thermal conductivity coefficient: 0.04 W/(m·K).
• - mu - 1 to 2.
• - c (specific heat) approximately 2100 J/(kg·K).
rock wool
Rock wool is a thermal insulating, non-combustible and rot-proof material. This material differs from other insulators in that it is a fire-resistant material, with a melting point greater than 1200 °C.
The main applications are roof insulation "Roof (construction)"), both inclined and flat (conventional European roof, with self-protected waterproofing sheet), ventilated facades, single-layer facades, interior facades, interior partitions, acoustic floors and floor insulation. When you have a tongue-and-groove tile roof, an uncoated felt or another with kraft paper on one side is used, which facilitates installation. In addition, it is used for passive protection of both structures, installations and penetrations.
Rock wool is sold in rigid or semi-rigid panels, felts, reinforced blankets and shells. It is also an excellent material for acoustic insulation in light construction, for floors, ceilings and interior walls.
• - Density: 30-160 kg/m³. According to EN 13162, in fiber from 20 to 150, in stone from 25 to 220.
• - Thermal conductivity coefficient: 0.034 to 0.041 W/(m·K). According to EN 13162, 0.035 to 0.05.
• - μ = 9 MN·s/g·m.
• - c (specific heat) approximately 840 J/(kg·K).
These are intertwined rock wool fibers. It is suitable for isolating horizontal construction elements, as long as it is placed on top. Vertically, it needs fastening or staples to prevent it from ending up caking at the bottom of the element and at the bottom of a horizontal element that is hanging down. They usually come protected by Kraft paper, tar paper, or light metal mesh.
These are panels agglomerated with some epoxy resin, which gives a certain rigidity to the insulation. It is used for vertical and horizontal construction elements at the bottom, in exchange for having a conductivity coefficient slightly lower than that of the blanket.
They are premolded tubes with different diameters and thicknesses. Like any good thermal insulator, the section must be chosen so that it is perfectly adjusted to the exterior surface of the conduction that is being insulated. Like all mineral wool, it is non-combustible. Rock wool resists temperatures up to 1000 °C.
glass wool
When you have a tongue-and-groove tile roof and you want to insulate it with glass wool, you should use a product for this purpose, which is a glass wool in panels with greater density, water-repellent and hygroscopic. When you have a sheet metal roof, the product line that should be used is the coating with a reinforced aluminum sheet on one side to act as mechanical resistance, as a vapor barrier and as a reflective material. As in the previous case, it is sold in the form of a blanket, agglomerated panels and pipe insulation shells.
• - Glass wool thermal conductivity coefficient: 0.032 W/(m·K) to 0.044 W/(m·K).
natural sheep wool
It is the natural and ecological version of woolly insulation. Unlike rock wool or glass wool, sheep wool is obtained naturally and does not require high-temperature baking. It is very resistant and a powerful humidity regulator, a fact that contributes enormously to the interior comfort of buildings. It is hardly used in construction compared to glass or rock wool.
As in the previous cases, it is sold in the form of a blanket, agglomerated panels and flakes.
• - Density: 20-80 kg/m³.[1].
• - Thermal conductivity coefficient: 0.043 type I glass wool W/(m·K)[2].
• - μ from 1 to 2.
• - c (specific heat) approximately 1000 J/(kg·K).
expanded glass
In addition to being an insulator, it is a very effective vapor barrier, which is not normal for thermal insulators and makes it very suitable for insulating thermal bridges in construction, such as pillars in façade walls. It is made of glass, generally recycled and without problems of color treatment, since the color of the product does not matter, it is foamed hot, leaving cells with enclosed gas, which act as an insulator. Its rigidity makes it more suitable than other insulators for covering it with plaster. It is little used in construction. It is also known as Cellular Glass and is still manufactured today, 2013, in Spain under the latter name.
• - Density: 20 kg/m³.
• - Thermal conductivity coefficient: 0.045 W/(m·K).
Expanded polystyrene (EPS)
Polystyrene foam material is an insulator derived from petroleum and natural gas, from which the plastic polymer styrene is obtained in the form of granules. To build a block, a certain amount of the material that is related to its final density is incorporated into a metal container and water vapor is injected that expands the granules until the block is formed. This is cut into plates of the desired thickness for marketing using a hot metal wire.
Due to its combustibility, flame retardants are incorporated, and it is called Hardly Flammable.
• - It has good thermal behavior in densities ranging from 12 kg/m³ to 30 kg/m³.
• - It has a conductivity coefficient of 0.034 to 0.045 W/(m·K), which depends on the density (as a general rule, the higher the density, the lower the conductivity coefficient).
• - μ from 140 to 250 MN·s/g·m depending on density.
• - It is easily attacked by ultraviolet radiation, which is why it must be protected from sunlight.
• - It has a high resistance to water absorption.
• - It does not form a flame since when it burns it sublimates.
cellulose foam
The cellulose foam material has acceptable thermal insulating power and is a good acoustic absorber. It is ideal for applying to the bottom of sheds because it is a completely white fireproof material and because of its speed when placed. It melts at temperatures above 45 °C. It is little used in construction.
• - Thermal conductivity coefficient: 0.065 to 0.056 W/(m·K).
polyethylene foam
Polyethylene foam is characterized by being economical, water-repellent and easy to install. Regarding its thermal performance, it can be said that it is of average character. Its finish is white or aluminum.
• - Thermal conductivity coefficient: 0.036 to 0.046 W/(m·K).
Polyethylene honeycomb film
In the same way as polyethylene foam, bubble wrap covered with aluminum foil is simply used as a thermal insulator. The advantages it has over other insulators are: very low thickness (3-5 mm), simple installation, very low cost; It is also non-flammable and recyclable. This film is used in construction, and more commonly in air conditioning equipment.
polyurethane foam
Polyurethane foam is known for being a very good performing insulating material. It has multiple applications as a thermal insulator both in construction and in industrial sectors. It stands out throughout the cold chain for its high energy efficiency.
• - Thermal conductivity coefficient: 0.023 W/(m·K).
• - μ from 96 to 180 MN·s/g·m depending on density.
Elastomeric foam
It is an insulator with excellent performance at low and medium temperatures and easy installation, reducing labor costs to a minimum. It has a vapor barrier in its structure and completely fire-retardant behavior.
• - Conductivity coefficient: 0.035 W/(m·K).
• - Optimum working temperature: -40 to 115 °C.
It is easily attacked by ultraviolet radiation, so it must be protected from sunlight.
Airgel
As a thermal insulator, airgel comes in flexible blankets (service range: -40°C to 650°C or -270°C to 90°C). It only comes in thicknesses of 5 mm and 10 mm. It has great mechanical properties for the performance it offers, it is hydrophobic (repels moisture), it is permeable (it allows air/vapor to pass through), it prevents corrosion under the insulation, it is fireproof (it does not catch fire) and it is extremely resistant to harsh treatment (stomping, blows, etc.). Its installation is intuitive and simple, the material can be cut with scissors or cutters, reducing time and excessive labor costs.
• - Density: 0.020 g/cm³ (Monolithic Airgel), from 0.13 g/cm³ to 0.18 g/cm³ (Aerogel in flexible blanket).