Another thing I have realised is that I have no lighting inside the airlock area. I will certainly not need a permanent light here and the ideal would be a light triggered automatically and that provides enough light to see the computer and the studio switching (light switch & fan controller). I might be using the area to store some items as well. I've looked around at various options and I found a bulkhead light with a PIR built in. It doesn't look particularly pretty but it will be functional. This does mean that I'll need to add an additional isolator switch for the PIR which will fit neatly next to the fan control switches on the left hand side. I'll just need to take another feed from the lighting junction box and run it through the stud-work down to the switch and up to the bulkhead light itself. The light will fit in the top left corner as you go in to shine towards the right hand side where the computer etc. lives. I picked the light up from ScrewFix so I can install this at the weekend.