Sun position (day/night)
Night-flush airflow
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Buildings with heavy thermal mass — exposed concrete, masonry, thick rammed earth — absorb the day's heat slowly and release it hours later, flattening the indoor temperature swing that a lightweight structure would otherwise transmit almost instantly. This simulator runs a simplified RC (resistance-capacitance) thermal model of a single building zone against a sinusoidal outdoor day/night cycle, lets you switch the shell's thermal mass and toggle night-flush ventilation (pulling in cool night air to purge stored heat before the next day), and tracks how many degrees of peak indoor temperature — and therefore cooling load — that combination avoids compared to a lightweight, unflushed reference building.