the role of "for" in "for all the tropical heat of the room itself"

The enormous room on the ground floor faced towards the north. Cold for all the summer beyond the panes, for all the tropical heat of the room itself, a harsh thin light glared through the windows, hungrily seeking some draped lay figure, some pallid shape of academic goose-flesh, but finding only the glass and nickel and bleakly shining porcelain of a laboratory. Wintriness responded to wintriness.

This is the beginning of Brave New World by Aldous Huxley. In the article in the BBC Arts site, Sarah Dillon analyzes the second sentence:

The ‘cold’ of the first clause governs the second clause as well, even though it’s not repeated at the beginning of it. This is called ‘zeugma’. ... So the first cold might well be literal, but the second cold must be figurative.

Then, the first for is used to show a length of time (for all the summer beyond the panes). But, what is the role of the second for (for all the tropical heat of the room itself)?

This use of for means something like despite:

for prep
9. Notwithstanding; despite: For all the problems, it was a valuable experience. TFD

So we could translate Huxley's sentence like this:

The enormous room on the ground floor faced towards the north. Cold despite all the summer beyond the panes, despite all the tropical heat of the room itself, a harsh thin light glared through the windows . . .

The only other thing that might help you understand the text would be that the subject of the second sentence is suspended until the third clause: a harsh thin light.