I have a pump room built as an extension to my conservatory. Three outer walls are 9" brick external/white block internal. There's a timber dividing wall from the conservatory. The roof is hammered wired glass, and there's virtually no ventilation. In direct sunlight it gets hot!
I'm considering using Nixol greenhouse shading paint on the outside of the roof, but would also like to put some vents at high and low level on opposite walls to get some air circulation. Google turns up loads of
100/125/150mm ducting, anyone know of anything smaller, say 50mm? I reckon a couple on each side will suffice. 50mm would also be much easier to instal.