How important is power consuption when you do datacenter design, Do we have to consider very carefully, Who does power consumption design for most datacenters.
Power consumption is critical if you under estimate then you run the risk of circuit breakers constantly tripping, this would not be to good for your advertised uptime.
The other issue is the possible fire hazard if your power cables cannot handle the load then they could start a fire.
I would agree with slaine. There's few things I would put above the ensuring uptime, but power is extremely important for the reasons just given, particuarly fire. If you don't do it right, then be prepared for the consquences.
Most colo companies are making huge markups on power. HUGE.
Most IT people don't understand how power, power rates, demand, etc. really works as that's not really their job anyway.
Price the parts that you are apt to pay attention to low, estabishing trust and then stick it to them on the items they aren't concerned about or don't understand.
Everyone needs a to make a reasonable profit and in a price sensitive market you have to make your margin somehwere. All in all colo can be much less expensive then a do it yourself data center.