CELLULOSE WOOL: AN EFFECTIVE INSULATOR
The thermal performance of insulation is measured based on its thermal conductivity (lambda), density, and phase shift.
ENVIRONMENTAL REQUIREMENTS AND COMFORT OF LIVING IN THE SUMMER
With summer seasons getting hotter, insulating homes against heat has become an important consumer requirement, reflected in the latest environmental regulations. The thermal properties of cellulose wadding ensure real comfort in summer, when outdoor temperatures are at their highest. Blown-in cellulose wool insulation with a thickness of 35 cm helps keep the inside of the house cool for about 9 hours, while traditional insulation materials can only withstand 3-4 hours of outside heat. This makes the room temperature less sensitive to fluctuations in outside temperature.
SLOWING DOWN HEAT EXCHANGE
In summer, the sun's rays fall directly on the roof of the building, and the temperature on its surface can easily exceed 50°C. Therefore, it is important that its insulation slows down heat exchange for as long as possible to allow the building to be ventilated at lower outside temperatures. Metal and tile roofs combined with plasterboard ceilings have low thermal inertia, so blown-in insulation in the attic must provide a large phase shift to ensure comfort in both winter and summer.
SAVINGS ON HEATING AND AIR CONDITIONING
Thanks to its high phase shift, cellulose wool saves energy throughout the year. In winter, the cellulose insulation layer retains heat longer, reducing the need for heating systems. In summer, it reduces the load on air conditioning systems.
THERMAL PERFORMANCE CRITERIA
HEAT TRANSFER COEFFICIENT
The thermal conductivity of a material, known as its lambda value, is its ability to conduct heat. The lower the conductivity (lower lambda value), the greater the insulating capacity of the material.
*When applying using the blow-in method
DENSITY
Density represents the weight of one m3 (cubic meter) of insulation. It is a parameter taken into account when calculating phase shift, i.e., the material's ability to store heat: thus, higher density contributes to improved thermal properties of insulation in both summer and winter.
*When applying using the blow-in method
U-VALUE: HEAT TRANSFER COEFFICIENT
The U-value describes the ability of a material to resist heat flow. Its value depends on the thermal conductivity (lambda) and thickness of the material. The lower the permeability, the more insulating the material is. To compare the parameters of different insulation materials in terms of their thermal resistance, it is necessary to compare the thickness of insulation required to achieve a specific thermal transmittance value U.
Thickness after settling (R = 7 M2.K/W):
Thickness after settling (R = 10 M2.K/W):
*Source: ACERMI Isover and Rockwool certificates / When using the blow-in method
PHASE SHIFT
Phase shift is the time it takes for heat to pass through insulation. The higher the phase shift, the longer it takes for heat to pass through insulation.
*When applying using the blow-in method
Time required for heat to pass through a 35 cm thick layer of insulation:
Thanks to its lower thermal conductivity, higher density, and better phase shift than mineral wool, cellulose wool has a significant impact on comfort in summer, limiting overheating of rooms and ensuring comfort for the building's residents.
OTHER ADVANTAGES OF CELLULOSE WOOL
Cellulose wool also has other advantages that allow for greater thermal comfort inside the building.
Hygrothermal properties of cellulose wool
As is the case with sponges, hygroscopic properties refer to the material's ability to absorb excess moisture, retain it, and release it when the atmosphere becomes drier, without changing its thermal properties.
This natural regulation process limits water vapor condensation and its negative effects, such as mold growth. Air with controlled humidity (containing between 30% and 60% humidity) also requires less heat to warm it up. We feel more comfortable in such an environment.
Cellulose wool is hygroscopic, which means it can absorb moisture up to 15% of its weight and release it when the atmosphere becomes drier. It is a very good moisture regulator and breathable material.
With a μ value of 2, cellulose is also open to water vapor diffusion and contributes to creating a healthy hygrothermal climate for people inside the building.
Behavior of cellulose wool during a fire
The density of cellulose wool and the addition of flame retardants ensure its appropriate reaction to fire. In the event of a fire, the surface of the material will char, which will slow down the spread of flames.
Due to its dense structure composed of recycled paper fibers, cellulose wool slows down air circulation in and between the fibers. Thanks to the use of flame retardants and the texture of the product at the end of the manufacturing process, cellulose wool is highly fire resistant.
This is because airflow through cellulose wool is virtually eliminated, which hinders the spread of fire in the insulation. Cellulose wool gradually chars on the surface, thereby preventing the spread of fire.
MASS AND HEAT PERMEABILITY
In uninsulated attics, cellulose wool with a thermal resistance value of U = 0.128 W/m²K can be used, blown onto plasterboard ceilings, screwed to support battens spaced every 60 cm and fixed to ceiling beams using hangers spaced every 1.20 m.
Mechanical behavior tests of the ceiling under distributed load were conducted by ECIMA (Association of French Cellulose Wool Manufacturers) and showed deformation of less than 5 mm with an insulation weight of 16 kg/m².
This confirmed the effectiveness of blowing cellulose wool into the ceiling with a U-value of 0.128 W/m²K in uninsulated attics.
| U-value | 0.167 | 0.143 | 0.125 | 0.11 | 0.10 | 0.91 | 0.83 |
|---|---|---|---|---|---|---|---|
|
Insulation layer (mm) |
300 |
350 |
400 |
450 |
500 |
550 |
600 |
|
Ceiling load (DaN) |
28 |
29 |
30 |
31 |
32 |
33 |
34 |
Two reference samples of NF drywall were tested, CERIB reports No. 012932 and No. 012933 dated November 20, 2018.
The test frame must have a destructive load equal to at least three times the working load of the frame indicated in the table, confirmed by laboratory testing.
BEHAVIOR ON A VENTILATED ROOF
The weight of cellulose wool ensures its excellent stability in attics. Necessary ventilation, even in stormy conditions, does not affect its thickness and thus its performance.
The phenomenon of settling is taken into account in the operating parameters certified by. It is determined by means of standardized tests carried out as part of product certification. Therefore, the certified thermal resistance of Igloo cellulose wool is given for the minimum thickness of the installed insulation, which corresponds to the minimum thickness after installation.
Thanks to its properties, cellulose wool is a comprehensive solution for building insulation. Its excellent thermal performance meets new environmental requirements for the use of air conditioning in summer and saves energy throughout the year. Other features that distinguish it from traditional insulation include its reaction to fire, hygroscopic properties, behavior in attics, carbon footprint, and service life. For over 100 years, it has been used in countries with large temperature fluctuations, such as Canada and Finland, where every second house is insulated with this material.
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