Thermal

Thermal insulation

Thermal insulation limits heat transfer between hot and cold ambiances by reducing heat exchanges between the inside of a building and the external environment.

Heat is transferred by:

• Conduction (the greater the material’s insulating properties, the less conduction)
• Convection (the more immobile the air, the less convection)
• Radiation (the more radiation absorbed, the less thermal transfer)

In a building insulated in accordance with RT 2005 (French norm), the residual part of the thermal breaks becomes much more important.

Thermal insulation on the underside of high floors (ceilings in cellars, car parks, basements, under floor spaces…) designed to reduce the two essential causes of heat loss:

• Losses to the heated floor above
• Losses through thermal breaks

Insulation is important for comfort and to save energy.

Conductivity and thermal resistance

The thermal resistance of a wall depends on the thermal conductivity of its constituent materials and the thickness applied. In the case of ISOTHERM spray-applied insulation, thermal resistance is provided by the air trapped between its criss-crossed fibres, reducing its movements to the maximum extent possible. As a result of its application in one go, this technique prevents thermal breaks (comparable to « short circuits » in internal insulation) and guarantees that there is no heat loss at joins. The absence of connections (mechanical fixings) boosts ISOTHERM’s  thermal performance.

Thermal resistance (R) is based on the following two parameters:

• Thermal conductivity λ (the lower the λ value, the greater the material’s insulating properties)
• Material thickness « e »

Material resistance R is given by the relationship:

Using the same principle,

The higher the insulation value R, the more absorbent the material.

The thermal transmission coefficient (Up) is a wall insulation indicator. The lower it is, the lower the loss.

The value Up is directly related to all resistance of the constituent R materials in the wall, and is defined by the relationship

Lexicon:

RT 2005 (French statutory regulation), sets building minimum energy performances in terms of energy consumption and thermal comfort.

It responds to the transposition into French law of the European directive (2002/91/CE) on building energy performance of 16 December 2002.

The latter sets out a common regulatory framework for the national regulations of member States, each country stipulating its level of requirement.

RT 2005 divides mainland France into eight climatic zones.

It covers residential and non-residential new buildings and applies to building permit applications submitted after 31 August 2006 (but does not apply in French overseas departments).

There are 5 associated labels:

• HPE 2005 (high energy performance)
• THPE 2005 (very high energy performance)
• HPE ENR 2005 (HPE 2005, high energy performance, reinforced by supplementary conditions)
• THPE ENR 2005 ((the most demanding THPE, very high energy performance, and renewable energies)
• BBC 2005 (low consumption building).