Wall insulation u value calculator formula

- Sep 27, 2018-

wall insulation u value calculator formula

What is U Value ?

What U Values are ? insulation u values are the measurement common used in construction industry, used to measmatchure the insulating efficiency of certain elements within a property. U Value is the value of heat flow rate per unit matcharea of the material, for 1 (degree)C difference.This provides a data of how effective each element is at preventing heat transmission. 

Generally speaking, a low number of U Value indicates high insulating efficiency, mean that this material it is very good at retaining heat.




Wall insulation U Value 

U Value is the value of heat flow rate per unit area, for 1 (degree)C difference.

U Value is an indicator used to evaluate the insulation effect of the home wall insulation. It is used to measure the velocity of heat flow in and out of the wall which separating indoor and outdoor. If the U Value of the wall is lower it mean that the insulation effect of the house wall insulation is better,because the heat flow from outdoor to indoor are more slower. 

The unit of U Value is W/m²K. For example, a window with u value of 2W/m²K, mean that per square meter have 2 watts heat flow if every degree of temperature difference between the interior wall and the exterior wall.

The U Value can be calculated by calculating the Thermal Resistance (R Values in m squared K/W) of each layer of the wall and the and Ri and Ro of the air layer inside and outside the wall,

here is the formula:

U Value= 1/ (ΣR + Ri + Ro)


 What is insulation r value?

The calculation of R Value of a certain layer of material can be calculated through the following formula:

R-Value = thickness of the layer/thermal conductivity of the material (W/mK)


If a wall is composed of many layers of material, the calculation may be complex.some building technical have suggested values for U Value of wall according to the commonly used construction, as shown in the following form.




Starting with a good building construction system that gives a better U value and air-tightness, as well as eliminating thermal bridges,which  reducing the energy demand and the property’s running cost,is becoming increasingly important.

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