kVAh

kVAh indicates Apparent Power. This measure is used because equipment and electricity networks are designed according to maximum voltage and current criteria, not to usable (kWh) power.

The most collocation providers will charge the Ampère in kVAh, so if you have bad power supplies in your rack, you will consume a lot more current, since your kVAh is larger than if it would be charged in kWh!