Backing arrangement

Rigid backing

The default arrangement in Zorba is for the absorptive material to have a solid backing such as a concrete or brick wall or other heavy structure.

In many countries walls are commonly constructed as cavity walls with relatively lightweight linings such as plasterboard. Zorba can predict the performance of porous materials with a lightweight backing by clicking on the check box at the bottom of the main picture. The picture changes to reflect the panel backing and you can now enter the width of the air cavity and the mass of the wall lining and choose whether the cavity contains an absorptive blanket or not.

Cavity absorbers

Note that provided the absorptive blanket is more than about 1000 Rayls/m and more than 25 mm thick then the absorption of the system is not very sensitive to the cavity absorber properties.

Double layers

To predict the performance of two layer absorbers you click on the check box at the bottom of the main picture.

The picture changes to reflect the two layers, now enter the flow resistivity and thickness of each material.