# How do you calculate thermal resistance? ### How do you calculate thermal resistance?

The thermal resistance R (in m2. K/W) depends on the thickness (e expressed in meters) and the conductivity thermal (λ) of the material: R = e / λ.

### What R for insulation?

In construction, the recommended thermal resistance in walls to a building to low consumption or BBC, is R greater than or equal to 4 m2. K/W. In renovation, to be eligible for aid to energy renovation, you must aim for a insulation of thermal resistance (R) minimum of 3.7 m2. K/W.

### What is the coefficient of thermal conductivity?

This coefficient is only valid for homogeneous materials. It does not make sense for heterogeneous materials through which heat propagates at the same time by conduction, convection and radiation. The coefficient of thermal conductivity λ of a material varies according to its temperature and humidity.

### What is Thermal Conductivity?

The thermal conductivity, noted λ (lambda) expressed in W/mK, is what will make it possible to measure the quantity of energy, of heat which is propagated by conduction: in one second, on a surface of 1m² of a wall measuring 1m thick, for a temperature difference of 1°C between the two sides of the material.

### How to calculate the thermal conductivity of a wall?

The thermal conductivity of the wall is 1 {,}68.10^ {-2} WK −1 .m −1. The thermal conductivity of the wall is 1 {,}68 WK −1 .m −1.

### How to measure the thermal conductivity of a material?

The coefficient of thermal conductivity is expressed in W/mK (Watt per meter per Kelvin, one Kelvin being equal to a variation of one degree Celsius). The meter is the ratio between thickness and surface. and How to measure the thermal conductivity of a material?