A few thoughts.
In an ideal world you would take the cost per sq ft, and the cost per kwh, and then work out some metric of the two when allocating from Data Centers to the infrastructure element. e.g. 0.6 x costs per sq ft + 0.4 x cost per kwh.
However, you are then going down quite a risky strategy as you are then reliant on having power consumption and U count for every bit of infrastructure you are allocating to. I would therefore use the thing that you are sure you are going to have the data for.
In most instances this seems to come back to U count.
That being said an alternative for the perfect data would be to use cpu cores and internal disk size as proxy for power usage and size.
The power consumption and size of the DC is still interesting for allocating from ITRT to the DC, if the specific DC is not in your finance data.
Michael