Having build a few smaller data centers in my time I have an interest in the topic.

Came across a new organisation The Green Grid. They have an interesting white paper on Guidelines for efficient data centers.

There is some interesting info and its very practical. There is the usual stuff like hot and cold aisles and so on. However it does mention some issues which I have seen in the field but you don't hear reported much such as this one.

COORDINATION OF AIR CONDITIONERS
Many datacenters have multiple air conditioners that
actually fight each other. One may actually heat while
another cools and one may dehumidify while another
humidifies. The result is gross waste that may require
a professional assessment to diagnose.