The Room section contains parameters that control how ARCHLine.XP calculates the usable or net area of rooms.

These settings are particularly important for rooms located below sloping roofs, as well as rooms containing columns, chimneys, niches or stairs, because not every part of the geometrical floor area necessarily contributes equally to the calculated net area.

ARCHLine.XP supports different room calculation rules, including:

• DIN 277
• WoFlV – Wohnflächenverordnung
• Norm I – Italian Norm

The selected standard and the corresponding Room settings determine which parts of the room are included, partially included or excluded from the calculated area. 

Understanding floor area and net area

The geometrical floor area represents the complete floor surface enclosed by the room boundary.

The net area is the area obtained after applying the calculation rules associated with the selected standard.

Depending on the selected calculation method, the result can therefore differ from the geometrical floor area.

For example, a room under a sloping roof may geometrically have a floor area of 20 m², while only part of this area is counted as living area because some parts of the room have insufficient clear height.

This distinction is particularly important with the WoFlV calculation method. ARCHLine.XP's documentation describes three height zones for this method: below 1 m, between 1 m and 2 m, and above 2 m. 

Automatic space recalculation

Automatic space recalculation

When enabled, ARCHLine.XP automatically recalculates Room information when the geometry of the room or its bounding elements changes.

For example, modifying:

• a wall,
• the position or slope of a roof,
• a floor,
• a ceiling,
• or another room-bounding element

may change the room geometry and consequently its calculated area or volume.

Rooms created using Room by Walls are associated with their bounding walls and can follow modifications to those walls. 

Recommended setting: Enabled.

Embedded wainscotings

Embedded wainscotings

ON: Inside wall, OFF: inside the room

Defines how embedded wainscoting is interpreted in relation to the room boundary.

When enabled, the embedded wainscoting is considered to be located inside the wall.

When disabled, it is considered to extend inside the room.

This distinction can affect the internal room boundary and therefore the calculated room dimensions.

Superscript display

Use Superscript2

When enabled, squared units are displayed using a superscript character.

For example:

m² instead of m2

Use Superscript3

When enabled, cubic units are displayed using a superscript character.

For example:

m³ instead of m3

These options affect the graphical formatting of room-related area and volume values rather than the calculated numerical result.

Height-dependent Net Area Calculation

One of the most important functions of the Room settings is the ability to calculate usable area according to the clear height available above different parts of the floor.

This is especially relevant for:

• attic rooms,
• rooms below sloping roofs,
• rooms below stairs,
• spaces with varying ceiling heights.

ARCHLine.XP can divide the room floor into different height zones and apply different calculation factors to them.

WoFlV Net Area Calculation

For the WoFlV (Wohnflächenverordnung) method, the default settings shown in the Options panel are:

These parameters create three calculation zones.

Zone 1 – Height below 1000 mm

If the clear room height is below:

1000 mm

that portion of the floor does not contribute to the calculated living area.

Calculation factor:

0%

Therefore:

4.0 m² × 0% = 0.0 m²

Zone 2 – Height between 1000 mm and 2000 mm

Floor areas where the clear room height is between:

1000 mm and 2000 mm

are included using the value defined by:

% multiplier between minimum and secondary height for net area calc. (WoFlV)

With the default setting:

50%

For example:

6.0 m² × 50% = 3.0 m²

Only half of this floor area contributes to the calculated living area.

Zone 3 – Height above 2000 mm

Floor areas where the clear room height is at least:

2000 mm

are calculated using:

% multiplier above secondary height for net area calc. (WoFlV)

With the default setting:

100%

For example:

10.0 m² × 100% = 10.0 m²

The entire area contributes to the calculated living area.

This 0% / 50% / 100% principle corresponds to the WoFlV height treatment described in the existing ARCHLine.XP documentation. 

Example – Room below a sloping roof

Consider an attic room with a geometrical floor area of:

20.0 m²

Suppose ARCHLine.XP determines the following areas according to the available clear height:

Therefore:

Geometrical floor area = 20.0 m²

while:

Calculated WoFlV living area = 13.0 m²

This example illustrates why the calculated Room area may be smaller than the geometrical floor area.

Minimum height for net area (WoFlV)

Defines the lower height threshold used for WoFlV calculations.

Default:

1000 mm

Areas below this height are excluded when the corresponding multiplier is 0%.

In an attic room, this usually corresponds to the floor area closest to the lowest part of a sloping roof.

Secondary height for net area (WoFlV)

Defines the upper height threshold for the partially counted zone.

Default:

2000 mm

Areas above this height are counted using the multiplier specified in:

% multiplier above secondary height for net area calc. (WoFlV)

With the standard configuration this is 100%.

% multiplier between minimum and secondary height

Defines how much of the floor area between the two height limits contributes to the calculated area.

Default:

50%

For example:

8 m² × 50% = 4 m²

This makes the setting configurable rather than hard-coding the percentage into the calculation.

% multiplier above secondary height

Defines how much of the floor area above the secondary height contributes to the calculated area.

Default:

100%

Therefore, with the default configuration:

12 m² × 100% = 12 m²

Visual interpretation of the WoFlV settings

For a room below a sloping roof, the calculation can be understood as follows:

                     Sloping roof
                         /
                        /
                       /
                      /
          2000 mm ---/----------------  100% area
                    /
                   /
          1000 mm /-------------------   50% area
                 /
                /
_______________/______________________
       0%          50%          100%
      counted     counted       counted

In other words:

h < 1.00 m → 0%

1.00 m ≤ h < 2.00 m → 50%

h ≥ 2.00 m → 100%

The actual threshold and multiplier values used by ARCHLine.XP are defined by the corresponding fields in Item Settings > Room.

Norm I – Italian calculation

The Options panel provides two separate minimum-height parameters for Norm I:

Minimal height belonging to the net area (Norm I – SU)

Default:

1500 mm

Defines the minimum height criterion used for the SU calculation.

Areas that do not meet the specified height condition are treated according to the corresponding Norm I net-area calculation rules.

Minimal height belonging to the net area (Norm I – SNR)

Default:

1400 mm

Defines the corresponding minimum height criterion for the SNR calculation.

The separate SU and SNR values allow ARCHLine.XP to apply different minimum-height criteria to the corresponding Italian area categories.

Important: The exact legal meaning and applicability of SU and SNR depend on the applicable Italian regulation and project jurisdiction. The values in ARCHLine.XP should therefore be configured according to the requirements applicable to the project.

DIN 277

Minimal height belonging to the net area (DIN 277)

Default:

1900 mm

Defines the height threshold used by the corresponding ARCHLine.XP DIN 277 calculation.

However, DIN 277 should not be interpreted as equivalent to the WoFlV living-area calculation.

The existing ARCHLine.XP documentation specifically distinguishes the two approaches. Under DIN 277, room height does not affect area in the same way as the 0% / 50% / 100% WoFlV living-area calculation. DIN 277 deals with categories such as gross floor area, construction area and net room area, while WoFlV is specifically concerned with living-area calculations. 

For this reason, the 1900 mm ARCHLine.XP parameter should be documented as a program calculation parameter, rather than implying that DIN 277 generally excludes all floor area below 1.90 m.

Columns and chimneys

Room calculations may also need to account for structural elements located inside the room.

Subtract from room area the columns, chimneys whose floor area is greater than or equal to

Default:

0.1 m²

Defines the minimum footprint of columns, chimneys or similar elements that can be deducted from the room area.

For example:

A column measuring:

0.40 m × 0.40 m

has an area of:

0.16 m²

Because:

0.16 m² ≥ 0.10 m²

it satisfies the area criterion for deduction.

By contrast, a column measuring:

0.20 m × 0.20 m = 0.04 m²

does not meet the 0.10 m² threshold.

For WoFlV, the existing ARCHLine.XP documentation describes the treatment of chimneys, wall projections, cladding and free-standing columns using both area and height conditions. 

Height criterion for columns and chimneys

Subtract from room area the columns, chimneys whose height is less than or equal to (Norm I v. WoFlV)

Default:

1500 mm

Defines the additional height criterion used by the corresponding room calculation.

The area and height conditions work together to determine whether the footprint of the relevant element influences the calculated room area.

Because this parameter can be standard-dependent, it should not be interpreted independently from the selected Room calculation method.

Floor-level niches

Add to floor area opening niches down to the floor if depths exceed (Norm I v. WoFlV)

Default:

130 mm

Defines the minimum depth of a floor-level opening niche that can be included in the calculated room area.

For example, consider a window or door niche that extends all the way down to floor level.

If its depth is:

100 mm

it does not exceed the default 130 mm threshold.

If its depth is:

200 mm

it exceeds the threshold and can therefore contribute to the room area according to the applicable calculation rule.

The existing ARCHLine.XP WoFlV documentation likewise identifies 13 cm as the relevant niche-depth threshold. 

Stair areas

Take off the staircase areas of the stairs are higher than (DIN 277)

Default:

2000 mm

Defines the height criterion used when ARCHLine.XP determines whether an area associated with a staircase should be deducted according to the corresponding calculation method.

This is relevant where stairs or the space beneath them affect the usable/net area of a room.

Because stair treatment differs between calculation standards, this parameter should always be considered together with the selected Room standard.

How ARCHLine.XP calculates a Room

Conceptually, the Room calculation can be understood as a sequence:

Room boundary → Geometrical floor area → Height analysis → Standard-specific rules → Additions and deductions → Calculated net area

ARCHLine.XP first determines the room from its bounding elements. Rooms can be associated with walls, and the program can also use floors, roofs and ceilings in determining room geometry. 

The applicable calculation rules can then modify the resulting area according to factors such as:

clear height + columns/chimneys + niches + stairs + selected standard

The result is the calculated area that can subsequently be used by Room information, room tags, schedules and other supported documentation workflows.

Important distinction: Geometry vs. calculation rule

A useful principle for users is:

The Room geometry describes the physical space. The selected calculation standard determines how much of that space contributes to the reported area.

Therefore, changing a net-area parameter does not change the building geometry.

For example, changing the WoFlV intermediate multiplier from:

50% → 60%

does not modify the roof or room.

It only changes how much of the floor area located between the two height limits contributes to the calculated net area.

Room illustration

Example: A cross-section of an attic room with a sloping roof, showing three colored zones:

0–1000 mm → 0%
1000–2000 mm → 50%
above 2000 mm → 100%

And below it, the floor plan bar chart:

4 m² × 0% + 6 m² × 50% + 10 m² × 100% = 13 m² net area