Both of these photos have a nice interplay between the textures of the surfaces we can see and the negative space of the invisible, dark inside of the building.

There is a whole genre of Japanese literature and art that deals with ghostly encounters in abandoned structures. There’s a book in the SOU library with some great (and freaky) examples:
Japanese ghosts & demons : art of the supernatural /
edited by Stephen Addiss
LOCATION CALL # STATUS
3rd Floor N7352 J36x, 1985

I also think the font in the righthand typography works well because its letterforms are so geometrical. Putting the pivot on the O works well because the O is a perfect circle.

On the left hand image, the O reflects a humanist axis: the thick parts of the stroke are at a downward slope to the right. So does the rest of the text.

Nice job aligning the boundary between the two images in the upper righthand corner with the boundary between bookshelves in the image below.

I also like the way the sides of the yellow area isn’t strictly parallel.

Have you seen “Beat the Whites with the Red Wedge”?
http://en.wikipedia.org/wiki/Beat_the_Whites_with_the_Red_Wedge

https://www.ugallery.com/

I wonder what it would look like if you had a variation where the text ran off the page (so you didn’t get the complete message). Though that wouldn’t be very De Stijl. I recently read something that discussed De Stijl in the context of all of the Netherlands’ canals and dikes. Apparently the Dutch like to say that God made the Earth, but the Dutch made Holland, emphasizing that almost all of their environment is man-made.

I think it’s also interesting that you added green to this. Apparently whether to include green with red, yellow, and blue was a big controversy in De Stijl. Some people literally left the group over the issue.