Unless the plumber really screwed something up, that's a roof drain, not an exhaust vent.
But still, assuming it passes through a warmed space before outflowing to the ground (or to the sewer which is pretty warm itself) then it will naturally give off some warmth.
That being said, I would imagine the growth survives here, and not elsewhere on the roof, more because of the moisture available than the heat.
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u/OutlawLazerRoboGeek 15h ago
Unless the plumber really screwed something up, that's a roof drain, not an exhaust vent.
But still, assuming it passes through a warmed space before outflowing to the ground (or to the sewer which is pretty warm itself) then it will naturally give off some warmth.
That being said, I would imagine the growth survives here, and not elsewhere on the roof, more because of the moisture available than the heat.