Billable IT, Protected Load, Facility Load, and Service Cap Differ

12,000 kW of billable IT [TARGET] is not 12,711 kW of protected load [MODELED]. Neither is 14,391 kW of facility demand [MODELED], and none of the three is a 15,000 kW service cap [TARGET]. Four power figures are in daily use on this study, and three of them are routinely written as though they were a fourth. The spread between the smallest and the largest is 25 %. Each answers a different question. What follows is what a single sheet has to carry so that a substitution becomes visible on sight. It proposes no change to any of the four.

The Four Figures Answer Four Different Questions

Billable IT is a contract quantity — the only one of the four that is a commercial term rather than an engineering result. Protected load is what an uninterruptible supply has to carry, built as 12,000 plus 585 kW [MODELED] of cooling-distribution auxiliary load plus 126 kW [MODELED] of path loss. Facility demand is what on-site generation has to pick up, built as 13,317 kW [MODELED] of critical medium-voltage demand plus 1,031 kW [MODELED] of mechanical and house demand plus 43 kW [MODELED] of medium-voltage loss. The service cap is a ceiling and is recorded in the fixed-fact register as explicitly not an IT capacity basis.

Stated as questions rather than as symbols: what is billed, what may not be interrupted, what must be picked up, and what may not be exceeded. The four answers are 12,000, 12,711, 14,391 and 15,000 kW. No two of those questions have the same answer.

Substituting One Figure for Another Is Already on File

None of this is a hypothetical drawing problem. Every one of the substitutions has already occurred somewhere in the document set, which is why each now carries a written prohibition.

The fixed-fact register lists reading the service cap as a billable IT figure among the rejected errors that may not be revived, alongside a standing prohibition on deriving a power figure from the project name. The architecture record separately excludes sizing transformers, uninterruptible supplies and batteries on a 15 MW IT basis and then billing on 12 MW. The first freezable item in the Gate 1 closure record states that 15 MW is the facility input ceiling and 12 MW is billable IT, and prohibits a 15 MW IT equipment schedule outright [FACT]. Three separate documents, one error.

The more interesting case is the one with no prohibition attached, because it is not an error. The engineering register records a margin of 609 kW [MODELED] against the cap, computed from the 14,391 kW facility figure. The later heat-rejection basis recomputes steady facility demand at 14,125 kW [MODELED] under its own itemisation, giving 875 kW [MODELED] of margin, and 14,358 kW [MODELED] with battery recharge inside the envelope, giving 642 kW [MODELED]. That record is explicit that 609 kW and 875 kW are the same kind of quantity and must be compared with each other, while 642 kW belongs to a different envelope and must not be compared with either. One denominator name, three live values, none of them wrong.

The Sheet Must Show All Four Figures Without Substitution

Four bars on one scale, in the order of the four questions, each carrying its value, its unit, its maturity label and the revision it came from. The two gaps drawn as brackets rather than left to be inferred: 711 kW [MODELED] between billable IT and protected load, and 1,680 kW [MODELED] between protected load and facility demand. The cap drawn as a line across all four bars rather than as a fifth bar, because it is not a load and a bar would invite it to be read as one.

Any margin annotation names its envelope in the annotation itself — steady, or including recharge — because a margin figure without an envelope is the quantity this whole sheet exists to make impossible. And two things stay off the sheet: any arrow, equals sign or shared axis label implying that one figure substitutes for another, and any single "headroom" number.

Limits and open items

Confirmed: 12,000 kW is a contract quantity; 15,000 kW is a facility input ceiling and not an IT capacity basis; an equipment schedule built on a 15 MW IT basis is prohibited. [FACT]

Study values, not frozen: 12,711 kW and 14,391 kW and every component behind them — the 585 kW auxiliary allowance, the 126 kW path loss, the 13,317 kW critical medium-voltage figure, the 1,031 kW mechanical and house figure and the 43 kW medium-voltage loss. The 14,125 kW and 14,358 kW recomputations and the 609, 875 and 642 kW margins carry the same status. [MODELED]

Open: the item-by-item controlled load schedule behind the facility figure; the reconciliation between the two facility values, which the recomputing document registers as a change candidate and expressly does not apply to the shared fixed facts; and a qualification specific to the 14,125 kW column, whose weather chain the engineering record declares to have been developed against the wrong location, leaving its weather-dependent outputs as formula templates without site effect until a site-correct recomputation is completed. [HOLD]

Nothing here has been reviewed or sealed by an Engineer of Record. No quantity is released. No figure describes an installed or operating system.

Which of the Two Facility Figures Will the Sheet Carry

The 12 MW against 15 MW confusion is now prohibited in three documents, which means it is visible and largely handled. The facility figure is the one to watch, precisely because nothing about it is an error: two values live under one name, each correct inside its own record, and a bar chart renders them identically. What separates them is a revision number and an envelope label — which are also the two fields most likely to be dropped when a chart is redrawn for a presentation deck.

When this sheet is next redrawn, which of the two facility figures will it carry, and will the sheet itself say which?

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Source: K&K Data Service Inc., “Billable IT, Protected Load, Facility Load, and Service Cap Differ,” https://www.kkdatasvc.com/lab/electrical-architecture-and-failure-domains/four-denominators-on-one-sheet/.