Surfaces, holes & shading elements
Draw individual surfaces in rooms, holes in existing surfaces and free-standing shading elements as polygon or rectangle
Overview
Besides complete rooms, individual surfaces can also be drawn: room surfaces (assigned to a room, with a construction), holes in existing surfaces (e.g. ceiling openings, passages) and free-standing shading elements (neighboring buildings, extensions, canopies) that only affect the shading calculation.
Invoking
In 
Add mode the “Add geometry” panel provides three groups, each with two drawing variants:
| Group | Polygon | Rectangle | Prerequisite |
|---|---|---|---|
| Surface |  Polygon |  Rectangle | none |
| Hole |  Polygon |  Rectangle | exactly one surface selected |
| Shading |  Polygon |  Rectangle | none |
For a polygon you set any number of points, for a rectangle three (two for the first edge, the third determines the depth). Unlike the room floor plan, these polygons may be oriented arbitrarily in space — so you can draw directly on walls or sloped planes; the snap options and axis locks help with this. The points appear in the vertex table (see Draw rooms); Create polygon or Create rectangle completes the input.
Surface in a room
After the polygon is completed, the panel shows the Surface properties page:
- Name: — display name of the new surface (required, otherwise message “Please enter a meaningful name!”).
- Building: / Storey: / Room: — target room of the surface; using the ”+” buttons, a building, storey or room can be created directly. Without a room selection “First select a zone to which you want to add the surface!” appears.
- Construction: — construction for the component assignment of the surface; the Edit button opens the construction database.
Create surface creates the surface in the room. It is colored according to its slope and gets a component assignment in which the room side lies on side B of the construction.
Hole in a surface
The hole buttons are only active when exactly one surface is selected. The drawn polygon is projected onto the plane of the selected surface and cut out as an opening; on the properties page (Hole properties) you assign the name and finish with Create hole. If the polygon cannot be projected onto the surface, “Polygon cannot be projected onto selected surface!” appears.
Holes are pure geometric cut-outs without a component — in contrast to windows and doors, which are created as sub-surfaces with a window component, see Insert windows & doors.
Shading elements (anonymous surfaces)
Shading elements are surfaces without a room or component assignment. They appear in the navigation tree under a dedicated shading branch and enter exclusively into the shading calculation — they have neither construction nor boundary conditions and do not appear in the building energy balance.
On the properties page (Shading element properties) only the name has to be entered; Create shading element creates the object. Alternatively, shading bodies can also be created from imported OpenStreetMap buildings (button OSM to shading, active as soon as at least one OSM building is selected), see Shading geometry.
Good to know:
Consistently model neighboring buildings as shading elements rather than as “real” rooms: the simulation stays lean because neither components nor balance equations are created for shading bodies — they merely cast shadows on the façades of your building.