I found this presentation just sitting on Utah University's website for a 2011 data center project.
Found it interesting that this was 4,000 kW facility with 2,400 kW for critical load for a 1.7 PUE in 2011.
Here are pictures of the data center space during construction.
I can't recall where I have ever seen Generac generators at a data center site.
Generators to provide power in the event of a power outage
Brand new facility and their hot/cold aisle containment is not that impressive. I guess that would explain the 1.7 PUE at full load. Got to think the PUE is 2.0 during the early phases.
Once the racks were installed, airflow zones were created to channel cold air to the racks and contain and vent the hot air from the data center. Power is delivered to each row of racks from an overhead distribution system.