The Design and Organization of Data Centers/Appendix A

Air conditioning
Common Values

Chiller calcs
Assuming that all wattage consumed will end up as dissipated heat (servers do very little mechanical work or yield very little light);

Wattage times 3.41 = BTU/hr

Example:

Server draws 10 amps at 120vac 10 amps X 120 vac = 1200 voltamps (aprox 1200 watts) 1200 VA X 3.41 = 4092 BTU/hr