What Daylight Analysis does

Simulates how much daylight reaches each point on your floor — every hour of every day for a full year — and reports LEED-style sDA / ASE plus glare risk. It's built for design-stage decisions, not for certification submission.

Metrics:

LEED-style sDA · ASE

Checked against:

Radiance

Input:

.3dm + EPW

How it works

The same method a validated engine uses, deliberately stripped for browser speed. Trust the relative reads (option A vs B, which rooms are dark, which window does the work) — the simplifications bias absolute numbers in a systematic direction, so comparisons hold up even where the raw values drift low.

• A sky that changes with the weather, every hour of the year, from your EPW file.
• Checked against Radiance on room, skylight and deep-plan scenes.
• Per-window isolation + an hour-by-hour glare timeline.
• No EPW? Falls back to a steady-state CIE-overcast Daylight Factor (ballpark).

How to use it

1. Upload your model. Drag a .3dm, .obj, .fbx or .ifc file into the viewer. Keep floors, walls and windows on separate, named layers (or named objects in OBJ/FBX).
2. Check the layer roles. Layers named like "Floor", "Slab", "Glass" or "Window" are assigned for you, and a file you've opened before keeps its roles. Open Assign layers to fix anything else: at least one Floor (where the sensors go) and your Glazing.
3. Run only the levels you need. On a multi-storey model, the arrow beside Calculate picks which storeys to measure: all, the ground floor, or the lowest and top. Storeys you skip still shade the others, so results stay right and the run is faster. The G / 1 / 2 rail on the left edge of the model shows one storey at a time in section.
4. Load an EPW file. Pick a weather file for the project location — the sun-position math depends on it.
5. Set parameters. Glazing VLT (65% for clear double glazing), Workplane Height (0.76 m for desks), Grid (start at 1.5 m).
6. Run & read results. sDA ≥ 55% and ASE ≤ 10% = LEED v4.1 pass. Click a cell to see why that point is bright or dark.

Best used for

• Comparing design options (window size, orientation, massing) side by side.
• Spotting gloomy or glare-prone rooms early.
• Window-to-floor / depth-of-plan sanity checks.
• Pre-screening a model before paying for a stamped daylight study.

Not a substitute for

• USGBC LEED credit submission.
• Building-code compliance sign-off.
• Stamped engineering deliverables.

Known limits

• Light bouncing between surfaces is modelled; mirror-like reflections are not.
• Surface reflectances are typical fixed values, not material-specific.
• No automated-blind protocol — it's LEED-style sDA, not true LM-83 sDA.
• Angle-dependent glazing transmittance is modelled; the sun is a single ray, so there is no penumbra.
• Sky-lit ground is modelled; sunlight landing on the ground outside is not, so clear-sky results read slightly low.
• Checked against Radiance across a set of room, skylight and deep-plan scenes; mid-room depths read slightly high, so treat absolute values as directional.

Read the full Daylight Analysis guide →