The summary.
EQUIPMENT CONVERTS ESSENTIALLY ALL ITS ELECTRICITY INTO HEAT
A rack consuming several kilowatts produces several kilowatts of heat, continuously.
On cooling failure, temperature rises in minutes — it is more urgent than most people expect.
ASK WHETHER COOLING IS ON GENERATOR POWER
Power restored without cooling buys very little time.
MEASURE AT INTAKES, NOT ROOM AVERAGES
A room averaging an acceptable temperature can contain equipment running far too hot.
Measure at several heights — the tops of racks are usually worst.
RUNNING COLDER THAN NECESSARY WASTES SUBSTANTIAL ENERGY
Acceptable ranges are wider than most people assume, but fix air separation before raising supply temperature, or you create hot spots.
FIX THE CAUSE OF A HOT SPOT, DO NOT COOL THE ROOM HARDER
That wastes energy and frequently does not reach the hot spot at all.
RECHECK AIRFLOW AFTER EVERY LAYOUT CHANGE
Layout changes routinely break arrangements nobody rechecks.
REMOVE DECOMMISSIONED EQUIPMENT
It consumes power and cooling for nothing, and there is always more of it than anyone expects.
