We have collected the questions that may be important for our customers. If you have any further questions, please contact us and our colleagues will be happy to answer them!

The R-value indicates the resistance of the insulation material against the heat flux. The higher the R-value is, the more efficient the heat insulation is.

The R-value depends on the type of the insulation material, the thickness and last but not least on the density of the body. Pick the thicker material and it will increase the R-value in your home and you can save money by decreasing the escape of the heat to the outside.

Of course, the efficiency depends on the quality of the installation and the professional selection of the material.

R-value (the higher figure means better insulation)

Material R-value* Source
Polyurethane foam 6.64 Glacier Bay Thermal Study
Polyisocyanurate foam 6.35 Glacier Bay Thermal Study
Polyurethane (rigid sheet) 5.8-6.2 IFAS, University of Florida
Polystyrene (extruded) 5.0 IFAS, University of Florida
Polystyrene (pressed) 3.9-4.4 IFAS, University of Florida
Polystyrene (expanded) 3.84 IFAS, University of Florida
Cellulose 3.2-3.7 IFAS, University of Florida
Glass wool (sheets) 3.2 IFAS, University of Florida
Glass wool (blown) 2.2 IFAS, University of Florida
Rock wool (unknitted) 2.0 IFAS, University of Florida

* R-value at 2.54 cm thickness

If there is a building structure that might be a wall, a slab, a bolster or anything else and the temperature is not equal on both sides then in every case the heat starts migrating towards the colder temperature from the warmer side.

Therefore in the summer the heat comes in and in the winter the heat exits the flat, of course this might sound odd but this is what we call heat transfer.

The heat insulation capability of every structure can be characterised by a figure. This figure represents how much heat can migrate from the side with the higher temperature to the side with the lower temperature if there are different temperature values on the two sides of the structure. This value ir “U” or “K”, the thermal conductivity coefficient.

If 1 m2 surface is inspected of a structure and it is known that 1.0 is the U-value, then this means that if the temperature is 10°C on one side of the structure and 11°C on the other, then the structure conducts 1 Watt heat energy.

The lower the U-value of a structural element is, the better its heat insulation is.

If the air barrier layer is formed but still heat loss is experienced then this is called convective circulation or heat transfer. The reason of this negative process lies within the material of the applied heat insulation. If breathable heat insulation material is used (e.g. glass wool, rock wool or other cellulose-based heat insulation material) then it will be filled with air that can freely move within the heat insulation.

So if we close it into a structure and there is air in it, even if it does not contact the internal or external environment – and this is a theoretic presumption. The internal warm air migrates upwards and the cold air outside migrates downwards, these movements start a circulation within the breathable heat insulation materials. The convective air circulation has always an opposite effect to the basic idea of the heat insulation: it heats the structure in the summer and cools it down in the winter. This way it causes heat loss; up to 50% weakening of the heat transfer resistance of the heat insulation can be experienced.

If this phenomenon is paired up with an imperfect air barrier, then some condensate water can be experience beside the heat loss and the water content results in thermal bridges that further cause heat loss. These processes mutually strengthen each other’s negative effects and consequently our heat insulation will be soon incapable of doing its job.

Those surfaces are called thermal bridges that have a different temperature (colder) than their respective environment. In their close proximity the air cools down and its temperature cools below the saturation point quickly. Then it emits the moist. If the humidity is too high then the bridges over the doors, windows, cold corners, cold walls and the floor become wet at these points.


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