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

Method:

Perez + daylight coeff.

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.

• Perez all-weather sky model (same family as Radiance's gendaylit).
• 145-patch Tregenza sky dome with the daylight-coefficient method.
• Annual hourly integration driven by your EPW weather file.
• 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

• Diffuse interreflection via radiosity (multi-bounce); specular/mirror reflections are not modelled.
• Fixed surface reflectances (wall 0.5 / ceiling 0.8 / floor 0.2), 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.
• Benchmarked vs Radiance across 8 space types (rooms, skylight, deep/tall, various windows): average Daylight Factor agrees within 4.9% on average and 8.9% at worst, and within about 1% at 6 m from the window. Annual sDA lands within ~3 percentage points across 8 further scenes. Mid-room depths read slightly high — treat absolute values as directional.

Read the full Daylight Analysis guide →