Surroundings Analysis

Overview

The Surroundings mode displays the sun position and the shading situation of the building model directly in the 3D scene. You choose any point in time during the year, the scene renders the corresponding shadow cast in real time, and for a selected surface or window the calculated shading factors (direct, diffuse, horizon) are shown – both as numerical values and as a color-coded sky dome. In addition, you can display a sun-path diagram with daily arcs and analemma hour lines as well as a sun sphere at the current sun position.

Displaying the shading factors requires that a shading-factor calculation has been performed beforehand; sun position, shadow casting and sun-path diagram work without it.

Access

Building workspace, left toolbar of the geometry view, button Surroundings (tooltip Change surroundings settings). The button is only visible in the Building workspace. When activated, the scene switches to the shadow-cast display mode and the Surroundings analysis panel appears.

Choosing a point in time (Time area)

In the Time area you set the point in time under consideration. It is based on hourly sun positions for all 8760 hours of the year, calculated from the latitude and longitude of the project location (see Climate & Location). If no location has been defined yet, a value of 51° North / 13.7° East is used.

• Carpet plot of the sun elevation – day of the year on the horizontal axis, hour of the day on the vertical axis, color-coded by sun elevation angle. A click in the plot jumps directly to the clicked point in time.
• Time slider – steps through the year hour by hour. Next to it are a date/time field (format dd.MM. HH:mm), a field with the hour of the year (unit h) as well as animation buttons (play/pause, to the beginning, to the end) with a speed control (tooltip Changes the animation speed.).
• Sun position – display of Azimuth: and Elevation: in degrees for the selected point in time.

With each change of time, the light direction of the 3D scene is updated: the model casts shadows according to the selected sun position. When the sun is below the horizon, shadow casting is deactivated.

Shading analysis for a surface

The Shading analysis area shows shading factors for exactly one selected surface or window:

• No selection: “No surface selected. Select a surface to visualize the shading factors.”
• Multiple selection: “Multiple surfaces/windows selected (n). Select exactly one for shading factors.”
• Exactly one surface/window selected: three values are shown as percentages (100% = unshaded, 0% = fully shaded):

Value	Meaning
Direct:	Shading factor for direct radiation, interpolated from the sky segments at the current sun position (azimuth/elevation of the selected point in time)
Isosky (diffuse):	Diffuse shading factor of the surface, weighted over the solid angles of all sky segments visible for the surface orientation and inclination (isotropic sky)
Horizon:	Shading factor of the near-horizon sky segments (lowest elevation band) for the surface orientation

The values come from the file <ProjectName>/input/shading_factors.tsv, which the panel loads automatically when opened. The sky model (Tregenza with 145 or Reinhart MF2/MF3/MF4 with 580/1305/2320 segments) is automatically detected from the number of rows in the file. If the file is missing, the notice “Surface ’…’ selected. No shading-factors file found.” appears – in that case, first run the shading-factor calculation.

With Reload shading factors, the file is read in again, e.g. after a recalculation with the panel open.

Visibility of the 3D displays

In the Visibility area, four checkboxes toggle the scene objects of the surroundings mode:

Checkbox	Default	Display
Show sky dome (shading factors)	off	For the selected surface, one sphere per sky segment is placed on a hemisphere around the surface, colored by the shading factor: red (0, fully shaded) through yellow to green (1, unshaded)
Show sun sphere	on	Yellow sphere at the current sun position on the dome radius; drawn only when the sun is above the horizon
Show sun-path diagram	off	Daily arcs, hour lines and ground grid (see below)
Show ground plane	on	Ground plane of the scene; identical to the menu item View > Show ground plane

Sun-path diagram

The sun-path diagram is drawn around the center of the building bounding box, with the configured dome radius as its radius. It consists of:

• 12 daily arcs (yellow) for representative days of the twelve months, calculated in 15-minute steps,
• 24 analemma hour lines (gray) – for each full hour, the path of the sun position over the year,
• a ground grid with a horizon circle, concentric elevation-angle circles (10° to 80°) and 16 radial compass-direction lines.

When switching to surroundings mode, the diagram is automatically re-anchored at the current bounding box of the building geometry.

Display settings

Setting	Value range	Default	Effect
Dome radius [m]:	1 – 300	200	Radius of the sky dome and the sun-path diagram; also the distance of the sun sphere
Sphere radius [m]:	0.1 – 10	1	Size of the individual sky-segment spheres of the sky dome
Sun radius [m]:	0.1 – 10	5	Size of the sun sphere
Ground plane color:	color picker	white	Color of the ground plane in the scene

Related topics

• Calculating shading factors
• Shading geometry
• Climate & Location
• Selection & Visibility