Thermal insulation

Thermal insulation:

Thermal insulation limits the transfer of heat between a warm and a cold environment thereby reducing the heat exchange between the inside of a building and the outside environment.

Heat can be transmitted in three ways:

• Conduction (the greater the insulating properties of a material, the lower its conductivity).
• Convection (the greater the insulating properties of a material, the lower its conductivity).
• Radiation (the more radiated heat is absorbed, the less heat is transmitted).

In a building isolated according to technical rules RT 2012, the residual part of thermal bridges increase significantly.

Thermal insulation applied on the undersides of slabs (cellar ceilings, car parks, basements, crawl spaces, etc.) reduces two fundamental sources of increased heat losses:

• Losses from upper heated floors
• Losses via thermal bridges.

This insulation plays an important role in ensuring comfort and energy savings.

Conductivity and thermal insulation:

The thermal resistance of a wall will depend on the thermal conductivity of the materials used to build it and its thickness. In the case of spray-applied ISOTHERM insulation, air gaps between the criss-crossing fibres trap the air and minimise resistance to the passage of heat, i.e. thermal resistance. Due to its joint-free application, this technique avoids the creation of thermal bridges. The absence of mechanical ties helps to improve the thermal insulating performance of ISOTHERM.

Thermal resistance (r) takes into account two parameters:

• Thermal conductivity λ (the lower the λ, the greater the insulating properties of the material)
• Thickness of the material "e"

The strength R of the material is given by the formula: R = e/λ

Similarly, e = R x λ

The more a material is resistant to the passage of heat (R), the greater its insulating capability.

The coefficient of thermal transmission (Up) is an indication of a wall's degree of insulation. The lower the Up, the less the heat losses.

The Up value is directly related to the total resistance of the materials R comprising the wall, and is defined by the conductivity-resistance-heat relationship: a formula that demonstrates the conductivity and the thermal resistance of the material.

Glossary:

French regulation RT 2012 establishes the minimum energy performances of the building in terms of energy consumption and thermal comfort.
It satisfies the transposition into French law of European directive (2002/91/EC) on the energy performance of the buildings dated 16 December 2002.
The latter establishes a common regulatory framework for member states' national regulations, each country defining its own level of requirement.