Thermal conductivity of polyurethane systems

The behavior of polyurethane systems as thermal insulation

Synthesia Internacional is a manufacturer and distributor of polyurethane systems that have multiple applications in the construction sector and in other relevant sectors such as the industry. The most popular polyurethane applications used in construction are by projection (projected polyurethane) and by injection (injected polyurethane).

Regardless of their application, all polyurethane systems are made of the result of the chemical reaction between a diisocyanate and a polyol. After such reaction, a safe and very versatile material is created which, depending on its combination with other substances, acquires certain properties that are highly valued in the construction and industrial environment, such as resistance, flexibility, rigidity or isolation. If you want to know in which daily objects polyurethane is present, we recommend you to visit IPUR’s website.

One of the properties thanks to which polyurethane systems have acquired great relevance in the construction sector is their optimum performance as thermal insulation: a fundamental characteristic when efficiency of buildings is at its peak.


Thermal Insulation and Polyurethane Systems

Polyurethane systems are among the best-performing insulation materials applied in construction. This insulating property is due to the structure of small cells that are formed inside the polyurethane, together with the composition of the gas occluded inside these cells.

Their structure ensures a low thermal conductivity thanks to which the thermal insulation values ​​required in the CTE are reached with a minimum of thickness. Compared to other materials, the thermal insulation provided by polyurethane is 700% better than the one provided by bricks and 50% better than the one provided by glass wool.

The thermal conductivity and the thermal resistance offered by polyurethane vary depending on the thickness, but thanks to its thermal coefficients, this thickness is much lower than in other insulating materials. This results in advantages regarding space and savings.

In all thermal insulation, whether it is polyurethane or other material, it is important to have a correct installation, so that the final result reaches the desired thermal performance. If the installation of the thermal insulation is not executed properly, we could have problems of air filtration, appearance of voids or presence of dirt, which would prevent the insulation assembly to offer a good performance.


Thermal conductivity of polyurethane systems

One of the properties that determines if a material has a good behavior as thermal insulation is thermal conductivity.

If we compare the thermal conductivity of the main insulation materials, we find that polyurethane systems offer better insulation thanks to their extremely low levels of conductivity.


Material Thermal conductivity
Brick 0.49-0.87 Km/W
Concrete block 0.35-0.79 Km/W
Expanded polystyrene 0.031-0.050 Km/W
Extruded polystyrene 0.029-0.033 Km/W
Polyurethane systems 0.022-0.028 Km/W
Mineral Wool 0.031-0.045 Km/W


Thermal resistance of an insulation material

Depending on the conductivity value indicated on the system’s datasheet, and once we know the thickness applied in your installation, the thermal resistance of a material for thermal insulation can be determined

The polyurethane systems are one of the materials that can obtain better thermal insulation with the minimum thickness. We have reached this conclusion after the multiple tests where the necessary thicknesses of different insulating materials are compared in order to obtain a certain degree of thermal insulation.

Although the differences in thermal conductivity levels between expanded polystyrene, extruded polystyrene, mineral wool and polyurethane systems (PUR) are of a few decimals (see table in previous section), they may represent a difference of 3-4 cm to obtain the same thermal performance.


Advantages of polyurethane systems for the thermal insulation of a building

 All the aforementioned characteristics make of polyurethane systems (in any of their applications: injected or projected) an optimum solution for the thermal insulation of both residential and tertiary buildings

In addition, we can avoid, thanks to the application of polyurethane systems the infiltration of cold air from the outside to the inner part of the chamber, which reduces the effectiveness of the thermal insulation up to 40%.

In the same way that the reduction of the currents that can be produced by the holes in the envelope (joints, blind holes, windows, doors …) would considerably increase the thermal conductivity.


Other applications of polyurethane systems

The property of polyurethane systems as thermal insulation is not the only advantage offered by their use in construction. We have a wide variety and a specific line of polyurethane for industrial and construction applications.


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