All construction materials have a measure of their thermal conductivity (Lambda value), used together, various materials will determine the overall thermal transmittance of a wall; this is known as the U-value. The lower the U-value, the more thermally efficient the wall construction is. A U-value will take into consideration the wall thickness & material and any render or insulation used – a typical solid wall (9 inch brickwork) used in a Victorian property has a U-value of 2.06 W/m2K.
Through the use of different insulation types and thicknesses in external wall systems, the thermal performance of a property can be dramatically improved and U-values of 0.30 W/m2 K and below can be easily achieved.
** 90mm of EPS will achieve a U-value of 0.30W/m2K in these situations.
Notes 1. The insulation thickness shown has been calculated with the latest available Lambda (λ) values for the insulation material declared by the manufacturers at the time of going to print. 2. Calculations are based on generic components and need to be verified for any particular structure, components and system. It is essential that you should request specific calculations based on the actual materials to be used. 3. Lightweight steel frame figures do not allow for any insulation medium placed within the studwork.