I agree with Len, as an operator of one of those large scale Data and Trading facilities we have often run into the exact situation. Rob comfort cooling to support Data, which is inevitably far more important according to IT, leaves people "Hot" under the collar. We pay the price for this, not the designers. My plant just 5 years ago was capable of providing 4000 tons of cooling. Today, and at a cost of at least 10 million dollars, we can support 6000 tons of cooling, and it is still not enough. So the whole picture needs to be looked at prior to all upgrades. Think future and add 50%.