i'm seeking opinions on what should just be straight forward budget pricing, but the more i look at it, the problems it's throwing up.

The air is approx 25m long, by 8.5m deep. O/all height is 2.7m ground floor and 2.8 for the mezz floor. (mezz is basically same size)

The front is all glazed, no shade or blinds etc and faces SW.

Space for plant is very limited on the roof, and i need fresh air at 12 l/s for 200 people.

Having done several methods of calc, they are all coming out bigger than the last, mainly solar from the windows and gain from the supply air.

I want to use outdoor ambient of 33c, maybe 35c to be safe.

Anyone got any feeling for total UK duty?