# Building Shadow Planning for Architects | SunCast

Explore how an extension or proposed building changes surrounding shadows. Compare dimensions, orientation and seasonal sunlight with SunCast Construction Mode.

Canonical HTML: https://suncastapp.com/solutions/architect
Last updated: 2026-09-22

## Direct Answer

Explore the sunlight trade-offs of an extension, a taller building or a different orientation. Use SunCast Construction Mode to place simple 3D building volumes and compare their shadows across the year.

## How It Works
1. Place the proposed building
2. Adjust its size and orientation
3. Compare shadows across the seasons

## Built for the Job
- **Building Shadow Simulator**: Place and save multiple 3D blocks, then adjust their width, depth, height and rotation to explore proposed building shadows.
- **Realistic Shadow Mapping**: Inspect how mapped neighbouring buildings and terrain affect the site. Check model coverage and dimensions before drawing conclusions.
- **AR Sun Tracker**: Relate seasonal sun paths to the real site during a visit. Check the direction of sunlight at a terrace, façade or proposed opening.

## Make sunlight part of the first sketch.

A footprint on a plan cannot show how a shadow moves through a garden. SunCast gives early design conversations a visual starting point, so you can explore alternatives before commissioning detailed analysis.

### Explore an extension

Represent a proposed extension with a 3D block and adjust its width, depth and height. Compare the shadow at the times the adjoining terrace or garden is used.

### Compare design options

Change a volume’s height, position or rotation and inspect the resulting shadow. Keep the date and time the same between options so the comparison reflects the design change.

### Look beyond summer

Compare winter and summer sun paths before relying on a sunny site visit. Use the map for surrounding context and AR on site to relate sun direction to existing buildings and openings.

Construction Mode uses simplified volumes and available map geometry. It supports preliminary visual planning, not certified daylight analysis, rights-to-light assessment or planning-permission evidence.

[Understand accuracy and limitations](/guides/how-accurate-are-sun-position-apps)

[Explore shadow length](/tools/shadow-length)

## FAQ

### Can I see building shadows?

Yes. Visualize Shadows shows realistic 3D shadows from buildings and terrain at any time of day or season. Construction Mode lets you preview how a planned building will change light and shadow on neighboring streets.

### Can I see the sun's path for different seasons?

Yes. SunCast can overlay the summer and winter solstice sun paths on both the map Solstice sun paths on the SunCast map and in AR December Solstice path in SunCast AR view — useful for understanding how light changes across seasons at any location. Enable them separately using the Solstice path toggles in Settings. Solstice path toggles in SunCast settings

### How accurate is the sun position?

SunCast uses precise astronomical calculations — accurate enough for professional photography, architecture, and location scouting. The sun moves gradually enough that results stay consistent across an entire neighborhood.