Level Difference Map for Building Noise

With the so-called Building Noise Map in conjunction with using variants the differences in facade levels at buildings can be calculated easily.

First, we calculate the building noise maps for all variants with Calculation|Calc, option „All Variants“. If we toggle variants by selecting the variant name at the toolbar the respective result is displayed on the screen.

To better recognize the levels, displayed in the symbols, deactivate the option „Color Symbols according to Level“, if necessary, or choose a different color palette with Open Palette in the menu Grid|Appearence|Option (see Grid Appearance).

Calculate Level Differences

We calculate the level differences by subtracting the results of the variants. For that, open the dialog Options|Building Noise Map and enter a formula in the dialog range „Arithmetic, assign active Variant“.

Example

Path: Examples\Immissions\Building Noise Map - Variants.cna

We calculate the first variant V01 with the actual situation and the second variant V02 with the actual situation plus noise protection measures, e.g. a noise protection wall. What level differences does the noise protection wall gain at the facades?

After calculating all variants (Calculation|Calc, option „All Variants“), we create another variant, e.g. V03 - differences - and activate this variant by selecting its name from the list box in the toolbar.

In the dialog Options|Building Noise Map, option „Arithmetic, assign active Variant“ enter the following:

LP1@V1 - LP1@V2

Click the button Perform Calculation. With this expression all evaluation parameters will be calculated if no other arithmetic field of has been checked.

If you want to calculate only a specific evaluation parameter you have to indicate the number of the desired evaluation parameter (LP1..4).

The expression in the above dialog means evaluation parameter 1 (LP1) of the variant 1 (@V1) minus evaluation parameter 1of the variant 2 (@V2).

The row names of the arithmetic fields (in this example „Day“ and „Night“) are changing depending on the name defined in the Calculation| Configuration, „Evaluation Parameter“ tab.

The button „Apply“ displays the result immediately without closing the dialog. Otherwise close the dialog by clicking the OK button.

Note

In this example the variant V03 will be overwritten if we calculate all variants again. The calculation of the level differences must be refreshed. The map of level differences for buildings is always displayed in the activated variant and therefore overwrites the existing result.

The functions, which you can use in the Arithmetic box, are identical with those from the Result Table.

For function and operators see CadnaA-manual "Attributes, Variables, and Keywords".