I don'think you are going to find a max temp ANYWHERE at present, although legislation is being contemplated.
All you can realistically do is do the calcs using a decent HVAC load package such as HEVACOMP, or if you can afford it, use TAS EDSL thermal modelling. These programmes estimate the summertime temps based on real weather and building conditions. (Heva comp uses the less accurate admittance procedure which over estimates the room temperatures, TAS uses a non-sinusoidal methodology which is quite accurate)
I would suggest that if the room exceeds 27-28C for more than say 6-7 days a year, you might consider cooling of some sort.
Friar Tuck of Sherwood