Free Daylight Calculator: Sun Patch, Daylight Factor and Sun Path for Any Room

Check how much daylight a room gets, for free, right in your browser, with nothing to install.

Set up a room and its windows, pick a city, a date and a time, and the Daylight Calculator draws the daylight on the workplane with the exact sun patch outlined in red. Hover any point for its illuminance, split into light from the sun, the sky and the room surfaces, with melanopic EDI and colour temperature. This tutorial plays a winter day in a Chicago room, counts the hours above 300 lux and the hours that meet WELL L03 tier 1 and tier 2, shows daylight factor under the CIE overcast sky with contour lines, adds buildings opposite and an overhang that blocks the summer sun, moves the window to the east wall, turns the building with the compass, reads the sun path diagram, switches to metric for London, opens the month by hour table for the year, saves the plan as a PNG and the grid as a CSV, copies a share link and opens the room in CircadianLab, where the colour scale opens fitted to the daylight, to add the electric light. Everything runs in your browser: the sun position comes from the NREL solar position algorithm, and the light inside the room from a radiosity solve with six bounces.

Calculate Daylight factor calculator, sun patch on a floor plan, sun path for a room, hours above 300 lux, WELL L03 daylight, melanopic EDI from daylight, overhang shading, buildings opposite (obstruction angle)

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