Turn a Daylight Factor into Overcast Daylight Autonomy — instantly.
A scientific calculator that converts the static DF into the dynamic DAo and DAo.con metrics — for single points, vertical sections and full floor-plan matrices, with heatmaps and response curves.
- 3
- Calculation modes
- 365×32
- Sky samples / point
- 0.00%
- Error vs. reference
Daylight supports part of the occupied time. Computed for latitude 37°, an 08:00–17:00 schedule and a 300 lx target — fully adjustable inside.
Complex daylight science, three simple steps
The hard part — a full annual overcast-sky simulation — runs instantly in your browser. You only ever think in Daylight Factor.
Enter your Daylight Factor
Provide DF at a point, along a vertical section, or across a whole floor-plan grid. DF is a static, location-independent indicator of a space's daylight performance.
We model the overcast sky
For every 15-minute step of the occupied year we compute the CIE overcast-sky exterior illuminance from solar geometry, then the interior illuminance as E = DF × E_ext.
Read DAo & DAo.con
DAo is the share of occupied time the space stays above your lux target; DAo.con also credits partial daylight. Results render as gauges, curves and heatmaps.
A faithful annual daylight model
This tool reproduces the original University of Seville workbook exactly. DAo is independent of orientation and location because it builds on the static Daylight Factor — yet the conversion still accounts for latitude, schedule and your illuminance threshold.
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Solar geometry
δ, equation of time, hour angle
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Solar elevation
γ = f(δ, latitude, H)
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Exterior illuminance
CIE overcast: (7/9)π(100 + 7580·sinγ^1.36)
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Interior illuminance
E_int = E_ext × DF/100
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DAo / DAo.con
count & continuous credit vs. threshold
Two metrics, one clear picture
Overcast Daylight Autonomy
The percentage of occupied time a point stays at or above the target illuminance (typically 300 lx) under overcast skies — the worst-case daylight scenario.
DAo = 50% → half the occupied hours need no electric light.
Continuous Overcast Daylight Autonomy
A nuanced version that also credits partial daylight: a point at 150 lx against a 300 lx target contributes 0.5 instead of being discarded.
DAo.con = 0.75 → on average 75% of the target is reached.
Three ways to calculate
From a single DF reading to a full floor-plan heatmap.
Make daylight performance obvious.
Open the calculator and convert your Daylight Factors into DAo and DAo.con — no install, no spreadsheet, instant visuals.