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āļø Solar Envelope Architect
Your neighbor to the north has a solar collector on their roof and a legal right to sun on it from 9am to 3pm, every day, worst case included ā the winter solstice. Push your building's height up and watch when, exactly, their panel goes dark. It's very rarely at noon.
Site
Latitude: 40Ā°N
Design day: Dec 21 (winter solstice)
Required access: 9:00ā15:00
Neighbor's collector: 15.0 m north of your building
Your Building
Live Result
ā
Shadow Reach at This Hour (m)
ā
Max Height for Full-Day Access (m)
šÆ Try the check-hour slider at noon vs 9am at the same building height ā the shadow is longer in the morning, not at noon, even though the sun feels "weakest" early. Find the tallest building that still keeps the collector lit all day.
Powered by the exact Cooper (1969) solar-position
formula, reused from the already-verified Sun Path & Shadow Explorer and
Kinetic Facade Explorer ā but computing a different quantity here: the
ground-shadow's north-south reach across an entire access window, derived by
projecting the roofline along the sun-ray direction onto the ground. A first
version of this formula used the wrong sign convention and was caught only by
an independent ray/ground-intersection cross-check before publishing (see
engine/solar-envelope.js).
Method
Ralph Knowles"Solar Envelope" (USC, 1970sā80s) ā maximum buildable height preserving a required daily solar-access window, not just a single-moment shadow.