Seal the open side of a "single" semi-detached house?

Hello,

I am building a semi-detached house (shell and roof are in place). Unfortunately, I do not know when the neighbors will start - but there is a construction obligation until mid-2021.
That also means that, in the worst case, my side will be open over the winter.

I want to move in around January/February 2021.

I am wondering what makes the most sense to do with the open side now? I have heard that people often put Styrofoam on it?
What is it actually about? Is it to prevent the walls (36.5 cm perforated bricks, otherwise uninsulated) from soaking up water? Or is it about thermal insulation?

In any case, I do not yet know when I will have the exterior plaster done.

Best regards!

Is it the weather page?

Is the east side.

If you take this to heart "The weather side is the bad side and is always NORTHWEST.", then I would say: no.

I would probably protect it at least against weather/moisture. Insulation probably wouldn’t "pay off" for one winter. I used to live next to a similar detached semi-detached house, which was practically bare for a solid ten years (however, made of KS bricks). At some point, the owners decided to insulate and seal everything, and promptly the construction of the second half began the following summer.

I thought the weather page is the side from which the wind usually blows, or not? Here the wind almost always comes from the southwest.

Best regards
Sabine