Model Geometry

This section documents the way the DesignBuilder model geometry you define is used in the calculations and visualisations. The description is based on the Model Geometry Example.dsb example building shown below. The file Model Geometry Example.dsb is supplied with DesignBuilder. The model consists of 4 blocks, each block containing a single zone, except the Ground floor block which is divided into equal sized North and South zones.

See the Visualisation Limitations section for information on some minor differences in the rendered images and the model used in the calculations.

1 x 10m x 10m Ground floor block partitioned into equal size North and South zones using partition of thickness 0.05m.

1 x 10m x 5m Block with flat roof and external floor connects with the First floor block on the North side.

1 x 10m x 10m Roof block with 45° roof slope drawn in the vertical plane and extruded horizontally, i.e. it is not defined as a Pitched roof block form. The Roof block is stacked on top of the First floor block.

30% Glazing ratio for all blocks, all glazing uses default facades (i.e. no windows or doors have been drawn).

Model uses default Zone volume calculation options - Internal floor constructions not subtracted from zone volume, External floor constructions not subtracted from zone volume and Ground floor construction is below ground and is not subtracted from zone volume.

When exported to 3-D DXF using the Whole model with details option and dimensioned the model looks like this:

The ceiling / floor surface between First floor block - Zone 1 and Roof block - Zone 1 has area 9.6m x (9.6 - 2 x 0.2 / sin 45°) where the 0.2 / sin 45° term is the Roof block wall thickness (0.2m) adjusted to account for the roof slope (45°) as shown in the diagram below.

The dimension data for the zones, surfaces and openings used in the calculations can be seen in the Navigator and can also be obtained by exporting a csv report file.

The tables below list the most important geometric data and show how each item is calculated. Note that surfaces with glazing have area of glazing subtracted. The areas below are consistent with EnergyPlus and SBEM calculations. Klima Europa calculations have modifications to wall area and volume calculations to ensure internal heights are used.

Additional information for Klima Europa users

The DesignBuilder interface to Klima Europa works slightly differently. With Klima Europa, calculations have modifications to wall area and volume calculations to ensure internal heights are used. A ratio is used to do this:

InnerVolumeToOuterVolumeRatio = (Volume - ConstructionVolumeForSubtraction) / Volume

The area of all vertical walls is multiplied by the above factor to ensure that only internal wall areas are used in calculations. Also the volume is reduced to account for internal and external floor constructions (but not by default for ground floors as these are by default taken as being below ground).

To achieve this Klima users should make the Zone volume calculation settings before running Klima Europa:

Zone volume calculation option	Recommended Setting for Klima Europa
Internal floor constructions not subtracted from zone volume	No
External floor constructions not subtracted from zone volume	Yes
Ground floor construction is below ground and is not subtracted from zone volume	Yes

These settings may be enforced when in Klima analysis mode in future versions.

Zone Ground floor block - North		Calculation Note
Floor area (m2)	46.08	4.8m x 9.6m
Volume (m3)	138.24	46.08m2 x 3m (subtract volume of ground floor if Ground floor construction is below ground and is not subtracted from zone zolume model option set)

Surface	Area (m2)	Area Calculation Note	Adjacency (Orientation / adjacent zone)
Ground floor	46.08	4.8m x 9.6m	Ground
Ceiling	46.08	4.8m x 9.6m	First floor block - Zone 1
Wall Outside	10.08	4.8m x 3m - glazing area on surface (2.88m x 1.5m)	90
Glazing Outside	4.32	2.88m x 1.5m	90
Wall Outside	20.16	9.6m x 3m - glazing area on surface (5.76m x 1.5m)	0
Glazing Outside	8.64	5.76m x 1.5m	0
Wall Outside	10.08	4.8m x 3m - glazing area on surface (2.88m x 1.5m)	270
Glazing Outside	4.32	2.88m x 1.5m	270
Partition	28.8	9.6m x 3m	Ground floor block - South

Zone Ground floor block - South		Calculation Note
Floor area (m2)	46.08	4.8m x 9.6m
Volume (m3)	138.24	46.08m2 x 3m (subtract volume of ground floor if Ground floor construction is below ground and is not subtracted from zone volume model option set)

Surface	Area (m2)	Area Calculation Note	Adjacency (Orientation / adjacent zone)
Ground floor	46.08	4.8m x 9.6m	Ground
Ceiling	46.08	4.8m x 9.6m	First floor block - Zone 1
Wall Outside	10.08	4.8m x 3m - glazing area on surface (2.88m x 1.5m)	90
Glazing Outside	4.32	2.88m x 1.5m	90
Wall Outside	20.16	9.6m x 3m - glazing area on surface (5.76m x 1.5m)	180
Glazing Outside	8.64	5.76m x 1.5m	180
Wall Outside	10.08	4.8m x 3m - glazing area on surface (2.88m x 1.5m)	270
Glazing Outside	4.32	2.88m x 1.5m	270
Partition	28.8	9.6m x 3m	Ground floor block - North

First floor block - Zone 1		Calculation Note
Floor area (m2)	92.16	9.6m x 9.6m
Volume (m3)	276.48	92.16m2 x 3m (subtract volume of ground floor if Ground floor construction is below ground and is not subtracted from zone volume model option set)

Block with flat roof and external floor - Zone 1		Calculation Note
Floor area (m2)	44.16	4.6m x 9.6m
Volume (m3)	132.48	44.16m2 x 3m (subtract volume of external floor if Internal and external floor construction is below ground and is not subtracted from zone volume model option set)

Roof block - Zone 1		Calculation Note
Floor area (m2)	90.569	9.434m x 9.6m (9.434m = 10 - 2 x 0.2 / sin 45°)
Volume (m3)	213.615	90.569m2 x (5m - 0.2 / cos 45°) x 0.5

Model Geometry Example

Additional information for Klima Europa users

Other related information