A model file can carry a glow map: a second picture, white where the surface gives off light of its own and black where it does not. useLoadModel reads it along with the colour picture, and the engine adds it after the lighting, so the code never sets a glow at all.
The sun goes down and comes back every twelve seconds. The bricks follow it; the windows, the doors and the sign stay exactly as bright, which at night is all that is left. bloom spreads them into the dark around them, the soft light of the GameCube and Xbox years, when consoles first drew a glow map in one pass.