Make Data-Centre Capacity a Typed Quantity, Not a Bare Number

Company editorial by Infrastructure Assets Group LLC

An infrastructure dashboard often makes a subtle modelling mistake: it stores a value and a unit, then loses the question the value answers. A field called capacity_mw might refer to a utility request, electrical input to a building, IT equipment or a heat-removal duty. Sorting that column produces a neat table, but not necessarily a meaningful comparison. Treating quantities as typed records makes the missing context visible.

1. Separate a rate from an accumulated quantity

NIST distinguishes energy, measured in joules, from power, measured in watts: joules per second. In common infrastructure reporting, MW describes a power level and MWh an energy amount. A constant illustrative load of 1 MW over two hours uses 2 MWh at the same measurement boundary. This arithmetic does not reveal the peak load, equipment rating or connection permission.

For a varying load, the energy amount depends on how the power changes throughout the interval. Dividing an annual energy total by elapsed hours gives an average, not a confirmed maximum. Berkeley Lab’s 2026 report makes the wider problem explicit: IT nameplate capacity, requested grid capacity and annual electricity consumption cannot be interchanged without additional information.

2. Make the physical boundary part of the type

A practical record should include quantity, unit, physical kind, boundary, time basis and evidence state. The following is an instructional example, not IAG facility data:

{
  "value": 1,
  "unit": "MW",
  "kind": "electrical_power",
  "boundary": "facility_input",
  "basis": "illustrative_constant_load",
  "duration_hours": 2
}

A separate record for requested connection capacity should carry its own boundary and status. Do not relabel it as available operating capacity because the numeric value is unchanged. Likewise, preserve whether a figure is a proposal, an equipment rating or an operating measurement. These labels are part of the data contract, not optional notes that disappear during export.

3. Distinguish heat-removal duty from electrical input

The watt is also a unit of heat-flow rate. Two quantities marked kW can therefore describe different things: heat transferred by a cooling system and electricity consumed to run it. A unit check alone cannot tell them apart. Add a physical-kind field and identify the equipment or interface being measured.

DOE’s design guide treats cooling performance separately from whole-facility energy metrics. Its water-efficiency guidance also illustrates how heat can move through several circuits before being rejected outdoors. A label such as liquid cooling describes part of that arrangement; it is not a substitute for the boundary of the recorded quantity.

4. Carry the reporting interval into each ratio

Annual PUE compares total facility energy with IT equipment energy over the reporting period. Site WUE compares annual site water use with IT equipment energy, in litres per kilowatt-hour. Their numerators measure different resources. Neither should be stored as an unexplained efficiency percentage.

Keep numerator and denominator totals, period, coverage and calculation method alongside the ratio. Distinguish a design estimate from a measured annual result. An annual PUE is not, by itself, a verified multiplier for converting a peak IT rating into required grid capacity: that calculation needs compatible boundaries and stated operating assumptions.

5. Reject incompatible comparisons before drawing a chart

A comparison routine can require matching physical kind and boundary, compatible reporting periods, consistent units and an explicitly accepted evidence state. Missing fields should produce an unresolved comparison, not a guessed conversion. Unit conversion can transform a known quantity; it cannot supply a missing connection agreement or measurement scope.

This approach also improves the explanation beside a chart. Readers can see whether they are comparing equipment designs, utility requests or recorded operation. The result is a more honest data product, not a claim that a particular facility has been qualified. The examples here are generic engineering proposals; they do not report IAG-owned capacity or measured operating performance.

Primary references

• NIST — Guide to the SI, Chapter 4: derived quantities and units
• Lawrence Berkeley National Laboratory — United States Data Center Energy Usage Report: 2025 Update (June 2026)
• DOE/FEMP — Best Practices Guide for Energy-Efficient Data Center Design (revised July 2024)
• DOE/FEMP — Cooling Water Efficiency Opportunities for Federal Data Centers (9 January 2019)