Do not put large transformers in HVAC space.
Encourage the use of dc power supplies. (12 24 48 72)
this is only %70 at full load http://www.powerstream.com/DC-PC-48V.htm other units can be %30-%75 see http://www.tomshardware.com/2004/01/22/getting_th
Take a look at heat pumps for local heat dumps.
Do not run your ac on UPS
Run your generators during peak loads
Use the heat from your gen set to cool the datacenter (continuous-cycle absorption cooling) http://www.nh3tech.org/absorption.html
Use solar / wind to recharge the battery bank.
smart non data center power use
turn off elevators/automatic doors during peak usage
use efficient low level/low power (led) lighting.
Have your users pay a heat tax per 100wt
Look not only at the cost upfront but the total cost over the life of the data center. There are a whole bunch more, but it depends on your needs/design/issues.