Building Noise Map

Using the object „Building Evaluation“ (see Building Evaluation) enables to display the maximum sound level across the storeys of a building where an exceedance of a limiting value occurs. Furthermore, a colored building noise map based on the level calculated for each storey is produced.

Note

In conjunction with the use of variants (see Variants) to calculate different scenarios, also level difference maps at building facades can be generated (see Level Difference Map for Building Noise) and displayed.

Procedure

• Insert the object „Building Evaluation“ with a mouse click on the building plan.
• In edit mode, double-click on the border of the building evaluation symbol and define a standard value by selecting the pertinent option.

The options for the data displayed on the building noise map are available on the menu Options|Building Noise Map.

• If necessary deactivate the option „No Calculation of Building Noise Map“ and set the further desired parameters by input or selection.
• Start the calculation with the pocket calculator from the symbol bar or with menu command Calculation|Calc.

Dialog Building Noise Map/ Building Evaluation

Dialog Building Noise Map/Building Evaluation (on Options menu)

Dialog options

Calculation

Facade points via/acc. to ...

Selecting the method used to generate facade sections:

• Facade points via facade lengths: The distribution of the facade points along the facades of the buildings is based on the minimum and maximum facade length.
• Facade points according to VBEB: The distribution of the facade points follows the regulation in VBEB VBEB-2006. The minimum facade length is therefore 2.5 m, the maximum 5 m.
• Facades according to CNOSSOS: The distribution of the facade points follows the regulation for CASE 1 from CNOSSOS-EU EU-2015 and EU-2021. For remaining adjacent segments according to case 1, part (c), a length of 2,5 m (instead of 5 m) is used. With this, the calculation is according to CNS-DE-2018 and CNS-DE-2021.

minimum/maximum Length of Facade

CadnaA subdivides the facade based on the entered length and inserts a level symbol into each section.

Distance Receiver-Facade (m)

This value specifies at which distance the facade points are generated off the buildings facade surface. In conjunction with the configuration setting for „Minimum Distance Receiver - Reflector“ (see Reflection Tab) this will define whether the facade levels consider the reflection at the building’s facade or not.

The default value is 0.05 m. The default setting for „Minimum Distance Receiver - Reflector“ of 1 m means that, the reflection at the building’s facade is not considered in the facade levels.

Additional Free Space

Is the distance from the facade point to the next obstacle smaller or equal to the value entered, no façade point/s will be generated and calculated. This may be useful when buildings have been imported having small gaps between each other, but should calculated as without gaps. The default value is 0 m.

Averaging Method

This selects the method for the calculation of the characteristic noise level of each building from the noise level of the facades (arithmetic, energetic average value, minimum or maximum value). The resulting value is shown inside the building evaluation symbol for the first two evaluation parameters (see Evaluation Parameters Tab).

Height is following terrain

With this option active, the facade points will no longer be generated based on the height of the building‘s first polygon point, but based on the terrain height at each facade position. As a result, the number of façade points varies (vertically) depending on the position and terrain shape. In this case, the heights entered in the Building Evaluation symbol (see Building Evaluation) refer to the ground height at each façade point position.

Note

Note that with this option active, the facade points are assigned to the floor designations (ground floor, 1st floor, etc.) based on the vertical sequence of the facade points starting from the ground floor and not based on their height relative to the ground.

Lower Receiver max. 20 cm below eave

With this option active, façade points will also be generated at building heights smaller than the height entered in the Building Evaluation symbol (see Building Evaluation). These are put at 20 cm below eave height of each building. Receivers below 2.0 m above ground are not generated. This option is needed for the calculation according to CNS-DE-2021.

No Creation of Building Noise Map

By activating this option, no noise map is calculated and displayed for the buildings. The building evaluation, however, is still executed as long as the symbol/s are activated.

Appearance of Building Noise Map

Show Facade Points

Select from the list box the facade points/levels to be displayed on the building noise map. The floor numbering as selected on the dialog Miscellaneous is used (see Miscellaneous).

Note

The storey’s designation can be displayed on the Result Table using the string variable STW (see Result Table in the CadnaA manual „Attributes, Variables, and Keywords“).

Option	Display of ...
none	no display of facade points
all	all facade points
top	the top row of facade points per building
max/min Level Facade	Min/Max-Level at each facade point position
max/min Level Floor	Min/Max-Level per floor (a single point per floor)
1st to 50th	for a distinct storey

Selecting the storey via the toolbar

As an alternative to the selection as described above, the floor to be displayed can also be selected in the plan view. To achieve this, open the Edit Toolbar dialog (Options menu) and shift the option „Select Floor“ from the left to the right column. After closing the dialog, an additional list box is shown enabling to select a floor of the building evaluation results. This feature is synchronized with the selection in the Building Noise Map dialog.

Symbol Type

Either „Octagon“ or „Ribbon“ can be selected.

Size of Exceeding/Not Exceeding Symbol

The size of the facade point symbols exceeding or not exceeding the limiting value may differ. Selecting the unit (m) will adjust the size of the symbol when change the scale, but not when selecting the unit (mm).

Color Symbols according to Level

Activating this option will colorize the facade point symbols according to the color palette specified via the menu Grid|Appearance.

Use rounded values

When this option is activated (default setting) the facade level displayed for each face point will apply the rounding rule as specified in the respective building evaluation symbol. Otherwise, the level not being rounded off will be displayed (integer value). In conjunction with the color palettes (see Grid Appearance and Color Palettes) and the option „Size of Exceeding/Not Exceeding Symbol“ this option can be used to define a rule for the color and the size of the facade point symbols applying the rounding or not.

option „Use rounded values“ activated (file BuildNoiseMap - Option Use rounded values ON.cna): The level at the lower left facade point is larger than 64.0 dB(A), but smaller than 64.1 dB(A). So, the limiting value of 64 dB(A) is respected considering the rounding rule 0.1 dB.	option „Use rounded values“ deactivated (file BuildNoiseMap - Option Use rounded values OFF.cna): The rounding rule is not considered when displaying the facade point levels. So, all levels larger than 64 dB(A) will be exceedances and displayed as such. *)

*) This setting corresponds with former releases of CadnaA (prior to release 4.1).

Example

Path: Examples\ Immissions

Open the file "BuildNoiseMap-Option Use rounded values ON.cna" in directory Examples\Immissions. The limiting value in this example is 64 dB(A) and the rounding used is 0.1 dB. Thus, applying this rule to 64.1 dB(A), for example, will cause a rounded value of 65 dB(A). Values form 64.0 to 64.1, however, will be rounded off to 64 dB(A) and respect the limiting value, consequently. Displaying the Result Table it can be checked at which facade points on the ground floor the level ranges between 64.0 and 64.1 dB(A).

In the next figure, the nominal level exceedances are indicated by a red color and an enlarged size of the facade point symbol.

Print in Symbols

Activation of this option will show either the level - in addition to coloring - within the level symbol. Alternatively, the number of the facade point number generated by CadnaA is displayed. The facade levels can be displayed in the Result Table (see Result Table) by selecting from the list box „Receivers from Building Noise Map“. The facade point numbers can be displayed in the Result Table by use of the string variable FASSNR.

Apply

By clicking the „Apply“ button, the actual the settings are applied instantaneously, without closing the dialog. When changing now the facade length the effect is just visible after a new calculation. By clicking the „Cancel“ button the altered settings will be ignored.

3D-Special View

The building’s facades are also displayed in colors on the 3D-special view according to the specified grid legend after a calculation.

Arithmetic

With the „Arithmetic“ field you are able to calculate different formula for or with the noise map of buildings, e.g. level-difference-map for building noise (see Level Difference Map for Building Noise)

In case a horizontal receiver grid has already been calculated you can allocate interpolated grid values to facade points. A separate calculation of a noise map for buildings is unnecessary which would save calculation time.

Independent from the number of defined evaluation parameters (see Evaluation Parameters Tab) the calculation results of the horizontal receiver grid provides a basis for the building evaluation.

Note

Prior to the allocation is that building evaluation symbols have to be addressed to the relevant buildings and the facade points been generated which can be generated by a „dummy“ calculation with a point source.

Double Arrow (>>)

gives access to pre-defined levels, levels in variants, spectral levels, limiting values, floor number, grid values, etc. (for the evaluation size LP1, analogously for LP2..LP4 ).

Example

1. calculate the receiver grid

2. generate face points with calculation of one single noise source (e.g. point source - all other noise sources deactivated with Modify Objects, action „Activation“, „Deactivate“ for all objects except the buildings and the building evaluation symbols

3. calculate the dummy noise map of buildings with the calculator symbol on the toolbar

4. On dialog Building Noise Map, dialog range „Arithmetic“ enter the expression r0 and click the button „Perform Calculation“.

By the expression r0 the interpolated calculation results of the horizontal grid will be allocated to the corresponding evaluation parameters of the facade points, not depending in what evaluation parameter’s input box (in this example Day|Night) the expression was entered. Subsequently, when selecting one of the evaluation parameters from the list on the toolbar, the respective results are displayed within the facade points.

To address interpolated results of the horizontal receiver grid, coordinates or the ground height to the facade points, the following additional expressions can be used in a formula:

Input	Result
r0	allocation of the results from the horizontal grid to all the corresponding evaluation parameters
r01 to r04	allocation to the corresponding evaluation parameter LP1 - LP4(r01 allocates the result to LP1, r02 to LP2 etc. - special application)
x, y, z	evaluates the corresponding x-, y- or z-coordinate of the facade point (z allocate the z-coordinate to the facade point - special application)
g	evaluates the ground height at the facade

Example

iif(STW==1, r0, LP1)

(in words: if it is the first floor then address the interpolated result from the grid - otherwise not, i.e. keep the existing value)

Object-Scan

Using the Object-Scan (see Chapter 14 - Extras) also facade points are selectable as object type for evaluation.

For the facade points the following attributes are available:

Attribute	Explanation
TOT_EINW	total no. of inhabitants of a building to which the corresponding facade point belongs to
FAC_EINW	number of inhabitants assigned to a facade point, with the same number of inhabitants is assumed per facade length
FAC_EINW_xy	number of inhabitants assigned to a facade point, weighted by applying the following options: - for x: L inhabitants weighted using the length of each facade section C inhabitants per facade section - for y: A for all facade points (includes also the deactivated ones, if any) (blank) just the „active“ facade points are considered
STW	floor identifier (ground floor=0, 1st floor=1, 2nd floor=2 etc.)
FAC_NR	number of facade points counted from the first point of the building (FAC_NR=1, FAC_NR=2 etc.) to the last facade point
FAC_LEN	corresponding facade 2D-length (m) of the facade point
TOT_LEN	sum of all facade lengths referring to the facade points
TOT_LEN_N	sum of all facade lengths referring to the facade points, facade lengths deactivated by the option „Additional Free Space“ are not considered
FAC_AREA	corresponding facade area (m²) of the facade point
TOT_AREA	sum of all facade areas referring to the facade points
TOT_AREA_N	sum of all facade areas referring to the facade points, facade areas deactivated by the option „Additional Free Space“ are not considered
TOT_FAC	number of facade sections
TOT_FACPTS	number of facade points
TOT_FACP_N	number of facade points, facade points deactivated by the option „Additional Free Space“ are not considered
CENTER_X	x-coordinate of the buildings center point
CENTER_Y	y-coordinate of the buildings center point
CENTER_ANG	angle between the buildings center point and a facade point, North direction = Zero
BLDG_AREA	building‘s ground area, for facade points
BLDG_ID	building ID (for facade points) - for internal use only
LPFLMAX1 .. 4	maximum level per storey for evaluation parameters 1 to 4
LPCNOSS1 .. 4	level according to CNOSSOS-EU per storey for evaluation parameters 1 to 4 (see Object-Scan,EU: Single Dwelling)

Example

If, e.g. the assigned number of inhabitants to a facade point should be evaluated select „Facade Point“ as object type and enter the following attributes and expressions in the input boxes:

for „Formula for Summation“: FAC_EINWfor „Formula for Total“: sum/num

for more information see Object-Scan