Why does the Data Hall cockpit show fixed numbers instead of accepting user input?

The cockpit is a locked-basis SCADA simulator, not a parametric calculator. All KPIs derive from CONV_CALC, a single deep-frozen conventional scenario object (IT load 1,850 kW, PUE 1.45, CHW 7.2/14.8 C). Immutability guarantees that every derived number is engineering-defensible and consistent across all pages of the conventional BMS suite.

How is PUE derived for the cockpit?

PUE = Facility Load / IT Load = 2,682.5 / 1,850 = 1.45. The 1.45 value is the locked basis constant from conv-engine.js (sourced from 09-engineering-basis-and-calculations.md line 11). Facility Load is then IT x PUE, not the other way around; PUE is the input, Facility Load is the derived quantity.

What is WUE and how is it computed?

WUE (Water Usage Effectiveness) = annual water consumption / annual IT energy (L/kWh). The instant equivalent is (water flow L/min x 60) / IT load kW. At basis: (37.0 L/min x 60) / 1,850 = 1.20 L/kWh, matching the basis constant in CONV_CALC.

Data Hall SCADA Console — Technical Manual & Methodology

01 Purpose & engineering basis

The Data Hall SCADA Console is a locked-basis cockpit simulator for a single conventional IT hall. It does not accept user inputs. Instead, every KPI on the instrument strip is derived from a single deep-frozen conventional scenario object — CONV_CALC — which holds the only authored inputs for the entire conventional BMS suite (dc-conventional, EPMS, datahall, chiller-plant, fire-system, fuel-system, water-system, ict). Immutability guarantees engineering consistency: a value displayed on this page will always reconcile with the same value on any other page in the suite.

The basis is documented in Documents/screenshot bms rz/conv/review/09-engineering-basis-and-calculations.md and codified in js/conv-engine.js. The governing accuracy rules (ACCURACY_VALIDATION 6 rules) are:

Rule	Description
`R1`	Single source of truth — every page reads from `CONV_CALC`; no page duplicates or hardcodes a value that conv-engine already computes.
`R2`	No Math.random() on basis KPIs — all KPIs are deterministic; values must be stable on reload.
`R3`	Explicit denominator on every metric — PUE = facility/IT; WUE denominator = IT kWh; carbon denominator = facility kWh (not IT).
`R4`	Marketing target ≠ derived value — design capacity (2,000 kW) and current load (1,850 kW) are separate constants; never conflate them.
`R5`	Terminology must match engineering basis — CHWS/CHWR labels, UPS loss formula, heat rejection path must match doc-09 exactly.
`R6`	Basis chip on every critical KPI — every displayed derived number carries a source annotation traceable to a line in the review docs.

No user inputs: this is a SCADA display cockpit, not a parametric calculator. The scenario is fixed to a real-world-representative conventional data hall. If you need to explore alternate PUE or CHW parameters, use the DC Conventional Calculator.

02 Locked basis parameters

These are the only authored inputs in CONV_CALC.model. Everything displayed on the cockpit is derived from this table — no other numbers are directly set.

Parameter	Key in CONV_MODEL	Value	Unit	Source (doc-09 line)
IT design capacity	`site.it_design_kw`	2,000	kW	09 line 9 ("IT design capacity 2,000 kW")
Current IT load	`site.it_load_kw`	1,850	kW	09 line 10 ("Current IT load 1,850 kW")
PUE	`site.pue`	1.45	—	09 line 11 ("PUE 1.45")
WUE	`environment.wue_l_per_kwh`	1.20	L/kWh	09 line 13 ("WUE 1.20 L/kWh")
Grid carbon intensity	`environment.carbon_kg_per_facility_kwh`	0.42	kgCO₂/kWh	09 line 14 (denominator = facility kWh)
Cold-aisle avg temperature	`environment.avg_temp_c`	22.4	°C	01-dashboard-review.md §"Right-Side Stats Panel"; ASHRAE TC9.9 recommended band
Relative humidity	`environment.avg_rh_pct`	48	%RH	09/01 environment row; ASHRAE recommended 40–60 % band midpoint
CHW supply temperature	`cooling.chws_c`	7.2	°C	09 line 15 ("CHW supply 7.2 C") — canonical CHW basis decision
CHW return temperature	`cooling.chwr_c`	14.8	°C	09 line 15 ("CHW return 14.8 C") — canonical CHW basis decision
Chillers running / total	`cooling.chillers_running/total`	2 / 3	—	01-dashboard-review.md §2 ("Chillers 2/3")
UPS efficiency	`electrical.ups_efficiency`	0.96	fraction	09 line 39 ("UPS losses @ 96% efficiency 77 kW")
UPS modules (2N)	`electrical.ups_module_count`	2	—	01-dashboard §"UPS A / UPS B", 2N topology
Metering tolerance	`electrical.metering_tolerance_pct`	±2	%	12-qa-acceptance-criteria.md line 9 ("within 2%")
Fuel tank capacity	`fuel.tank_capacity_l`	60,000	L	09 line 140 ("Tank capacity = 60,000 L")
Usable fuel fraction	`fuel.usable_fraction`	0.90	fraction	09 line 141 ("Usable fraction = 90%")
Fuel level (current)	`fuel.level_pct`	85	%	09 lines 16, 126 ("Fuel level 85%")
Generator consumption	`fuel.generator_consumption_lph`	956	L/hr	09 lines 144–147 (~956 L/hr at ~2.7 MW gives 48 hr)

03 Calculation methodology

Each derivation below maps one-to-one to a named function in js/conv-engine.js. The function name appears in the source tag; the formula is transcribed exactly from the engine. No constant is hard-coded inside these functions — all literals come from CONV_MODEL.

Facility Load

Facility Load [kW] = IT Load × PUE = 1,850 × 1.45 = 2,682.5 kW In facilityLoadKw(m). Total power at the utility meter, including IT + all overhead (cooling, UPS losses, lighting, BMS). PUE is the input constant; facility load is derived.CONV_CALC · facilityLoadKw · doc-09 lines 25–28

Non-IT Overhead Load

Non-IT Load [kW] = Facility Load − IT Load = 2,682.5 − 1,850 = 832.5 kW In nonItLoadKw(m). The overhead power consumed by cooling, electrical distribution, and support systems.CONV_CALC · nonItLoadKw · doc-09 lines 32–34

UPS Losses

UPS Loss [kW] = IT Load × (1 / η − 1) = 1,850 × (1/0.96 − 1) = 77.1 kW In upsLossKw(m). Input power above output at the stated UPS efficiency η = 0.96. Matches doc-09 line 39 ("UPS losses @ 96% efficiency 77 kW").CONV_CALC · upsLossKw · doc-09 line 39

CHW Delta-T

ΔT [°C] = CHWR − CHWS = 14.8 − 7.2 = 7.6 °C In chwDeltaT(m). Conventional chilled-water loop temperature rise across the CRAH coil. Basis locked at 7.2/14.8 °C per CHW basis decision (resolves the earlier 19.1/22.6 °C condenser-side confusion).CONV_CALC · chwDeltaT · doc-09 line 83

CHW Flow

Flow [L/s] = IT Load / (4.186 × ΔT) = 1,850 / (4.186 × 7.6) = 58.1 L/s In chwFlowLps(m). Sensible heat removal from the IT space. Constant 4.186 = specific heat of water kJ/(kg·K). The numerator is IT load (not heat rejection) matching the doc-09 canonical worked example (09 lines 81–85). Heat rejection (IT + UPS losses) is available as a sanity-check band.CONV_CALC · chwFlowLps · doc-09 lines 81–85

Water Flow / WUE

Water Flow [L/min] = (WUE × IT Load) / 60 = (1.20 × 1,850) / 60 = 37.0 L/min WUE check = (Flow × 60) / IT Load = (37.0 × 60) / 1,850 = 1.20 L/kWh ✓ In waterFlowLpmForWue(m) and wueFromFlowLpm(m, lpm). Instant-equivalent cooling-makeup water flow derived from WUE. WUE denominator is IT energy (kWh), not facility energy.CONV_CALC · waterFlowLpmForWue · doc-09 lines 99–104

Carbon Emissions

Carbon [kgCO₂/hr] = Facility Load × Grid Factor = 2,682.5 × 0.42 = 1,126.7 kgCO₂/hr In carbonKgPerHr(m). Denominator is facility kWh per Rule R3 (carbon is a facility-level metric, not IT-level). Grid factor 0.42 kgCO₂/kWh sourced from doc-09 line 14.CONV_CALC · carbonKgPerHr · doc-09 lines 155–158, 167

Fuel Autonomy

Usable Fuel [L] = Tank × Usable Fraction × Level% = 60,000 × 0.90 × 0.85 = 45,900 L Autonomy [hr] = Usable Fuel / Consumption = 45,900 / 956 = 48.0 hr In fuelUsableL(m) and fuelAutonomyHr(m). Usable fraction accounts for the tank heel (unusable bottom layer). Generator consumption 956 L/hr at facility load ~2.7 MW gives exactly 48 hr.CONV_CALC · fuelAutonomyHr · doc-09 lines 133–147

04 Constants & data sources

Every constant in CONV_MODEL carries a // source: comment referencing a review-doc file and line number. The primary authority document is conv/review/09-engineering-basis-and-calculations.md. Secondary references for individual values:

Constant	Value	Authority	Notes
Specific heat of water	`4.186 kJ/(kg·K)`	ASHRAE Fundamentals 2021 §Thermodynamics	Used in CHW flow and heat rejection calculations.
CHW supply / return	`7.2 / 14.8 °C`	doc-09 lines 15, 81–84; doc-00 §"Single Capacity Basis" line 62	Canonical basis locked to conventional chilled-water loop (not condenser side).
UPS efficiency η	`0.96 (96%)`	doc-09 line 39; IEC 62040-3 typical transformer-free double-conversion	Gives 77 kW loss at 1,850 kW IT (check: 1,850×(1/0.96−1) = 77.1 kW).
Grid carbon factor	`0.42 kgCO₂/kWh`	doc-09 line 14	Facility-energy denominator per R3. Facility = IT × PUE.
WUE	`1.20 L/kWh`	doc-09 line 13; Uptime Institute WUE benchmark (good: 1.0–1.4 L/kWh)	IT-energy denominator. Consistent with ASHRAE cooling-tower makeup at this PUE.
Metering tolerance	`±2%`	doc-12 line 9 ("within 2%")	Applies to EPMS total kW display; nominal = facility load without offset.
Generator consumption	`956 L/hr`	doc-09 lines 144–147	At ~2.7 MW facility load. Used only for fuel autonomy; cockpit does not display load-dependent fuel burn.
Tank usable fraction	`90%`	doc-09 line 141; typical heel volume for above-ground diesel storage	Bottom 10% of tank volume is typically inaccessible sludge / unusable heel.

05 KPI strip outputs

The cockpit renders the following nine KPIs from CONV_CALC.snapshot. Snapshot values are computed once at load and deep-frozen — they never change during a session.

KPI	Snapshot path	Value at basis	Unit	Derivation function
IT Load	`snapshot.site.it_load_kw`	1,850.0	kW	Authored constant (basis input)
Facility Load	`snapshot.site.facility_load_kw`	2,682.5	kW	`facilityLoadKw` — IT × PUE
PUE	`snapshot.site.pue`	1.45	—	Authored constant (basis input)
CHW Flow	`snapshot.cooling.flow_lps`	58.1	L/s	`chwFlowLps` — IT/(4.186×ΔT)
WUE	`snapshot.environment.wue_l_per_kwh`	1.20	L/kWh	Authored constant; verified by `wueFromFlowLpm`
Water Flow	`snapshot.water.flow_lpm_for_wue`	37.0	L/min	`waterFlowLpmForWue` — (WUE×IT)/60
Carbon Rate	`snapshot.environment.carbon_kg_per_hr`	1,126.7	kgCO₂/hr	`carbonKgPerHr` — Facility×GridFactor
Fuel Autonomy	`snapshot.fuel.autonomy_hr`	48.0	hr	`fuelAutonomyHr` — UsableL/ConsumptionLph
UPS Loss	`snapshot.electrical.ups_loss_kw`	77.1	kW	`upsLossKw` — IT×(1/η−1)

EPMS cross-check: snapshot.electrical.epms_total_kw = 2,682.5 kW (= facility load, within the ±2% metering tolerance per doc-12 line 9). The probe tools/probe-accuracy-validation.mjs asserts this reconciliation on every CI run.

06 Worked example — 1,850 kW scenario

The exact scenario displayed on the live cockpit. Each number is reproduced from CONV_CALC.snapshot and must match the live page within ±0.1 (one decimal place rounding).

IT Load (authored basis): 1,850.0 kW
Facility Load: 1,850 × 1.45 = 2,682.5 kW
Non-IT Overhead: 2,682.5 − 1,850 = 832.5 kW
UPS Losses: 1,850 × (1/0.96 − 1) = 77.1 kW (rounds to 77.1 kW; doc-09 states "77 kW" — within tolerance)
CHW delta-T: 14.8 − 7.2 = 7.6 °C
CHW Flow: 1,850 / (4.186 × 7.6) = 58.1 L/s
Water Flow: (1.20 × 1,850) / 60 = 37.0 L/min
WUE check: (37.0 × 60) / 1,850 = 1.20 L/kWh ✓
Carbon rate: 2,682.5 × 0.42 = 1,126.7 kgCO₂/hr
Usable fuel: 60,000 × 0.90 × 0.85 = 45,900 L
Fuel autonomy: 45,900 / 956 = 48.0 hr
Active racks at 6 kW/rack: floor(1,850 / 6) = 308 racks
Active racks at 10 kW/rack: floor(1,850 / 10) = 185 racks

Engineering reading: at PUE 1.45 and WUE 1.20 L/kWh this hall sits in the Uptime Institute "good" band for both metrics. The 48-hour fuel autonomy at full facility load provides one full-day runtime margin against the Uptime Tier III 72-hour N+1 generation target; extending to 72 hr would require ~60 % more usable fuel or a second supply route.

07 References & standards

ASHRAE TC9.9 (2021) — Thermal Guidelines for Data Processing Environments: cold-aisle temperature band (18–27 °C recommended), humidity 40–60 %RH, PUE/WUE benchmarks.
Uptime Institute Tier Standard (2022) — Tier III: N+1 redundancy, 72 hr fuel autonomy target; WUE benchmark scale (good: 1.0–1.4 L/kWh).
ISO/IEC 30134-2 — Data centre key performance indicators — Part 2: Power Usage Effectiveness (PUE). Defines PUE = total facility power / IT equipment power.
ISO/IEC 30134-3 — Data centre key performance indicators — Part 3: Renewable Energy Factor (REF). Referenced for carbon intensity context.
IEC 62040-3 — UPS performance and test methods: double-conversion (VFI) typical efficiency 94–97 % at full load; basis uses 96 %.
ASHRAE Fundamentals 2021 §Thermodynamics — Specific heat of water 4.186 kJ/(kg·K) at 10 °C (CHW regime).
conv/review/09-engineering-basis-and-calculations.md — Primary authority for all basis constants (IT load, PUE, CHW temperatures, WUE, carbon factor, fuel system parameters).
conv/review/00-overview-audit.md — Six data-quality rules and cross-page consistency contract for the conventional BMS suite.
Engine source — js/conv-engine.js (CONV_CALC v1.0.0) — deep-frozen scenario object + pure derivation functions.
Accuracy gate — tools/probe-accuracy-validation.mjs (40/40 assertions) + tools/test-conv-calc.mjs (22/22 DoD identities).

08 Assumptions & limitations

The cockpit models a single-hall, steady-state conventional data center at the stated load point. Key assumptions and their engineering justification:

Assumption	Basis	Impact if violated
IT load is stable at 1,850 kW	Locked basis; represents the current operating point per doc-09 line 10.	PUE, CHW flow, WUE, and carbon all scale linearly with IT load — if load changes, all derived KPIs shift proportionally.
CHW loop is conventional (7.2/14.8 °C)	CHW basis decision (conv-engine.js header); resolves the earlier 7.2/14.8 vs 19.1/22.6 °C conflict by assigning the higher temperatures to the condenser/secondary loop.	If the cockpit is adapted to a warm-water loop, ΔT increases and CHW flow drops; the chwFlowLps function must receive a different model object.
PUE is measured (not design target)	Basis is the observed operating PUE = 1.45, not the design-target 1.4 or nameplate. Rule R4: marketing target ≠ derived value.	Using design-target PUE would understate facility load and carbon by ~3–5 %.
Carbon factor is grid-average (not marginal)	0.42 kgCO₂/kWh is an annual grid-average intensity. Marginal intensity varies hour-to-hour.	Carbon rate should be interpreted as an annual average indicator, not a real-time dispatch signal.
Generator consumption is fixed-rate	956 L/hr at the full facility load ~2.7 MW. Actual consumption varies with generator loading.	Autonomy will be slightly optimistic at partial load (lower consumption) and pessimistic at above-design load.
Water flow is instant-equivalent	`waterFlowLpmForWue` converts the annual WUE to an instantaneous flow rate. Actual cooling-tower makeup is intermittent.	Displayed as a steady-state equivalent; suitable for capacity sizing, not for variable-flow metering design.
UPS is transformer-free double-conversion (VFI)	η = 0.96 corresponds to modern transformer-free double-conversion UPS at full load per IEC 62040-3.	Legacy transformer-based UPS (η ≈ 0.90–0.94) would increase UPS losses by 35–75 kW and raise PUE slightly.

Disclaimer: This cockpit and its methodology are an engineering education and pre-design reference. All values are derived from a representative simulated scenario, not from live telemetry. Final facility design, commissioning, and operational decisions must be validated by a qualified data-center engineering team against actual site measurements and authority-having-jurisdiction requirements.