When sizing airconditioning for electronics you have to figure out the wattage of the equipment and add in things like lighting , people , heat gain from windows etc. there is aprox. 3416 BTU per kw (if I remember correctly) so it should be fairly easy to figure out what you need and add a little for unknown heat gains . Measuring cooling loads in kw's is quite common in commercial HVAC . There is also lots of easy to use software for heat loss/gain calculations available .