pressure values too low

Hi

I am running the “Outdoor airflow” example file. I am trying to map pressure on walls and roof of the bigger block. Front, back and one of the side wall gives positive pressure results however roof, and another side wall gives result of <-100000000000000000000000000….Pascal

Is this trying to say pressure is negative on these sides.If yes, is there a way to map negative pressure on those meshes?