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.
and Visualisation view:
See the Visualisation Limitations section for information on some minor differences in the rendered images and the model used in the calculations.
The model consists of:
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 10m First floor block stacked on ground block.
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.
Above are external block dimensions.
Block wall thickness = 0.2m for all blocks.
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 3D DXF using the Whole model with details option and dimensioned the model looks like this:
The same model in 3D view 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 general principles used in DesignBuilder are:
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.
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) 
Surface 
Area (m2) 
Area Calculation Note 
Adjacency (Orientation / adjacent zone) 
Floor 
46.08 
4.8m x 9.6m 
Ground floor block  North 
Floor 
46.08 
4.8m x 9.6m 
Ground floor block  South 
Ceiling 
90.569 
9.434m x 9.6m (9.434m = 10  2 x 0.2 / sin 45°) 
Roof block  Zone 1 
Wall Outside 
20.16 
9.6m x 3m  glazing area on surface (5.76m x 1.5m) 
90 
Glazing Outside 
8.64 
5.76m 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 
9.6m x 3m  glazing area on surface (5.76m x 1.5m) 
270 
Glazing Outside 
8.64 
5.76m x 1.5m 
270 
0.201 
Necessary surround for interblock partition 
0 

28.649 
Interblock partition 9.6m x 3m  wall (with hole) (0.201m2) 
Block with flat roof and external floor  Zone 1 
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) 
Surface 
Area (m2) 
Area Calculation Note 
Adjacency (Orientation / adjacent zone) 
Floor 
44.16 
4.6m x 9.6m 
Outside 
Flat roof 
44.16 
4.6m x 9.6m 
Outside 
Wall Outside 
9.66 
4.6m x 3m  glazing area on surface (2.76m x 1.5m) 
90 
Glazing Outside 
4.14 
2.76m 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 
9.66 
4.6m x 3m  glazing area on surface (2.76m x 1.5m) 
270 
Glazing Outside 
4.14 
2.76m x 1.5m 
270 
0.201 
Necessary surround for interblock partition 
180 

28.649 
Interblock partition 9.6m x 3m  wall (with hole) (0.201m2) 
First floor block  Zone 1 
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 
Surface 
Area (m2) 
Area Calculation Note 
Adjacency (Orientation / adjacent zone) 
Floor 
90.569 
9.434m x 9.6m (9.434m = 10  2 x 0.2 / sin 45°) 
First floor block  Zone 1 
Wall Outside 
15.576 
9.434m x (5m  0.2 / cos 45°) x 0.5  glazing area (6.676) 
90 
Glazing Outside 
6.676 
4.45m x 1.5m 
90 
Wall Outside 
15.576 
9.434m x (5m  0.2 / cos 45°) x 0.5  glazing area (6.676) 
270 
Glazing Outside 
6.676 
4.45m x 1.5m 
270 
Roof (slope 45° ) 
64.042 
6.671m x 9.6m, 6.671 is the internal eaves to apex length = (5  0.2 / cos 45) / sin 45 
90 
Roof (slope 45° ) 
64.042 
6.671m x 9.6m, 6.671 is the internal eaves to apex length = (5  0.2 / cos 45) / sin 45 
270 