Why is the cockpit locked — no user inputs?

The EPMS/BMS cockpit is a real-time monitoring and anomaly-detection aid, not a design calculator. Its numbers represent a single authenticated engineering scenario (IT load 1,850 kW, PUE 1.45) anchored in conv review doc 09. Allowing arbitrary inputs would break the ACCURACY_VALIDATION 6-rule contract and produce engineering-indefensible output. All KPIs are derived deterministically from CONV_CALC.

What is the canonical chilled-water loop basis?

The primary (secondary) CHW loop runs at 7.2 °C supply / 14.8 °C return (ΔT = 7.6 K). This resolves the 7.2/14.8 vs 19.1/22.6 conflict documented in conv-engine.js: the ~19/23 °C readings are the condenser-side loop and are never labelled CHWS/CHWR in the cockpit. Source: conv review doc 09 lines 15, 81–84.

How is WUE derived and what does 37 L/min mean?

WUE = 1.20 L/kWh is the site water-usage effectiveness target (ISO/IEC 30134-2 definition: annual cooling-makeup water / annual IT energy). The cockpit converts it to an instant equivalent makeup flow: 1.20 × 1,850 / 60 = 37.0 L/min, which is the steady-state evaporative loss rate a cooling tower operator would monitor.

Conventional DC — EPMS & BMS Cockpit — Technical Manual & Methodology

01 Purpose & engineering basis

The Conventional DC cockpit is an EPMS/BMS monitoring and anomaly-detection aid for a chilled-water, UPS-backed, generator-protected data centre. It answers five operational questions in real time: what is the current energy balance, is cooling performing within design, how are the UPS modules loaded, how much fuel autonomy remains, and how do site sustainability metrics (PUE/WUE/CUE) compare to design targets.

This page is a cockpit, not a calculator. Its basis of design is fixed: the scenario constants in CONV_MODEL (locked, deep-frozen) drive every displayed number. The governing accuracy contract is the ACCURACY_VALIDATION 6 rules (one source of truth · no Math.random on basis KPIs · explicit denominator on every metric · marketing target ≠ derived value · terminology must match engineering basis · basis chip on every critical KPI), plus the 23 acceptance tests in tools/probe-accuracy-validation.mjs. Basis document: conv/review/09-engineering-basis-and-calculations.md.

02 Inputs — locked basis-of-design

There are no user inputs. The table below is the complete set of authored constants in CONV_MODEL. Every other number on every cockpit page is derived from these. Source citations map to conv review doc 09 line numbers.

Parameter	Symbol / key	Value	Unit	Source
IT design capacity	`it_design_kw`	2 000	kW	doc-09 line 9
IT load (current)	`it_load_kw`	1 850	kW	doc-09 line 10
Power usage effectiveness	`pue`	1.45	—	doc-09 line 11
Water usage effectiveness	`wue_l_per_kwh`	1.20	L/kWh	doc-09 line 13
Grid carbon intensity	`carbon_kg_per_facility_kwh`	0.42	kgCO₂/kWh	doc-09 line 14, denominator = facility kWh
Cold-aisle average temperature	`avg_temp_c`	22.4	°C	doc-01 §Right-Side Stats Panel; ASHRAE TC9.9 recommended band
Average relative humidity	`avg_rh_pct`	48	%	doc-01/09 environment row; ASHRAE 40–60% band midpoint
CHW supply temperature	`chws_c`	7.2	°C	doc-09 line 15, 81–84 — canonical primary loop
CHW return temperature	`chwr_c`	14.8	°C	doc-09 line 15, 81–84 — canonical primary loop
Chillers running / total	`chillers_running / _total`	2 / 3	—	doc-01 §2 dashboard KPI "Chillers 2/3"
UPS efficiency	`ups_efficiency`	0.96	—	doc-09 line 39 ("UPS losses @ 96% efficiency 77 kW")
UPS module count (2N)	`ups_module_count`	2	—	doc-01 §Right-Side Stats Panel (UPS A / UPS B)
EPMS metering tolerance	`metering_tolerance_pct`	2	%	doc-12 line 9 "within 2%"
Fuel tank capacity	`tank_capacity_l`	60 000	L	doc-09 line 140
Tank usable fraction	`usable_fraction`	0.90	—	doc-09 line 141
Fuel level	`level_pct`	85	%	doc-09 lines 16, 126
Generator fuel consumption	`generator_consumption_lph`	956	L/hr	doc-09 lines 144–147

Accuracy rule 4: None of these values is a marketing target presented as a measured outcome. PUE 1.45 is the engineering basis from doc-09, not a best-in-class aspirational figure. The cockpit displays these as design basis chips, not live telemetry.

03 Calculation methodology

All derivations are pure functions inside CONV_CALC. Function names below map one-to-one to js/conv-engine.js. No formula exists outside the engine.

Facility and non-IT load

Facility = IT × PUE → 1 850 × 1.45 = 2 682.5 kW Non-IT = Facility − IT → 2 682.5 − 1 850 = 832.5 kW In facilityLoadKw(m), nonItLoadKw(m). Facility is the total metered input to the site; Non-IT covers cooling, lighting, UPS losses, and all ancillaries. Both are rendered on the dashboard energy panel.doc-09 lines 25–28, 32–34

PUE reconciliation

PUE = Facility / IT = 2 682.5 / 1 850 = 1.45 (identity check) The cockpit renders PUE as the ratio Facility÷IT. The locked value must always reconcile to exactly 1.45 — any other display would violate accuracy rule 1 (one source of truth). Denominator is IT load (not design capacity).doc-09 line 11; ACCURACY_VALIDATION rule 3

UPS losses

UPS loss = IT × (1/η − 1) → 1 850 × (1/0.96 − 1) = 77.1 kW Per module (2N) = UPS output / count → 1 850 / 2 = 925 kW per module In upsLossKw(m), upsModuleKw(m). In the 2N topology each module carries the full protected IT load at 100% redundancy. At 50% shared-load operating mode each module runs at 925 kW. UPS output is taken as IT load (mechanical on gen-backed switchboard, not UPS).doc-09 line 39; doc-01 §UPS A / UPS B

Chilled-water loop

ΔT = CHWR − CHWS = 14.8 − 7.2 = 7.6 K CHW flow = IT load / (Cp × ΔT) → 1 850 / (4.186 × 7.6) = 58.1 L/s Heat rejection = IT + UPS loss → 1 850 + 77.1 = 1 927.1 kW (sanity band 1 850–1 950) In chwDeltaT(m), chwFlowLps(m), heatRejectionKw(m). Cp = 4.186 kJ/(kg·K) for water. CHW flow is sized on IT load per doc-09 worked example; heat rejection (IT + UPS loss) is the cooling-band sanity check per doc-09 line 77. The secondary condenser loop (~19/22 °C) is NEVER labelled CHWS/CHWR in the cockpit — it is a distinct loop relabelled per conv-engine.js CHW basis decision.doc-09 lines 81–85; doc-00 line 83

Water usage effectiveness (WUE)

WUE = annual cooling makeup water [L] / annual IT energy [kWh] = 1.20 L/kWh Instant equivalent flow = (WUE × IT) / 60 → (1.20 × 1 850) / 60 = 37.0 L/min In waterFlowLpmForWue(m). WUE definition per ISO/IEC 30134-2. The cockpit shows the steady-state equivalent makeup-water flow rate a cooling-tower operator monitors. The display value is 37 L/min — not "37 × 60 = 2 220 L/hr" on the raw basis chip; the fraction /60 converts kWh×L/kWh to L/min.doc-09 lines 99–104; ISO/IEC 30134-2

Carbon usage effectiveness (CUE)

CUE = carbon emission rate [kgCO₂/hr] / IT power [kW] Carbon rate = Facility × grid factor → 2 682.5 × 0.42 = 1 126.7 kgCO₂/hr CUE (IT-basis) = grid factor × PUE → 0.42 × 1.45 = 0.609 kgCO₂/kWh-IT In carbonKgPerHr(m). CUE per ISO/IEC 30134-8 uses the facility-energy denominator for the grid carbon factor (0.42 kgCO₂/kWh is stated as a facility-energy intensity in doc-09 line 14). The IT-basis form CUE = grid factor × PUE is a derived identity. Denominator must be explicit on every CUE display (accuracy rule 3).doc-09 lines 155–158, 167; ISO/IEC 30134-8

Fuel autonomy

Usable fuel = capacity × usable fraction × fill level = 60 000 × 0.90 × 0.85 = 45 900 L Autonomy = usable fuel / generator consumption rate = 45 900 / 956 = 48.0 hr In fuelUsableL(m), fuelAutonomyHr(m). The 48 hr design target is a Uptime Institute requirement for Tier III/IV continuous operations — validated against doc-09 lines 132–147.doc-09 lines 132–147; Uptime Institute Tier Standard

Active-rack estimates

Active racks = IT load / rack density (illustrative cross-sections) At 6 kW/rack: 1 850 / 6 = 308 racks At 8 kW/rack: 1 850 / 8 = 231 racks At 10 kW/rack: 1 850 / 10 = 185 racks In activeRacks(m, kwPerRack). Three density cross-sections per doc-09 lines 51–63. Shown as informational context on the IT panel, not as primary KPIs.doc-09 lines 51–63

EPMS power metering

EPMS total = Facility load = 2 682.5 kW (nominal; tolerance band ±2%) EPMS UPS output = IT load = 1 850 kW (mechanical on gen-backed board) In epmsTotalKw(m), epmsUpsOutputKw(m). Metering tolerance ±2% is a quality flag, not an applied offset — the cockpit shows nominal values. EPMS = Electrical Power Monitoring System.doc-00 line 77; doc-12 line 9

04 Constants & data sources

Every constant lives in the deep-frozen CONV_MODEL object with a // source: tag pointing to conv review doc line numbers. The snapshot table confirms all computed intermediates at the locked basis point.

Computed quantity	Function	Result	Unit
Facility load	`facilityLoadKw()`	2 682.5	kW
Non-IT load	`nonItLoadKw()`	832.5	kW
UPS loss	`upsLossKw()`	77.1	kW
CHW ΔT	`chwDeltaT()`	7.6	K
CHW flow	`chwFlowLps()`	58.1	L/s
Heat rejection	`heatRejectionKw()`	1 927.1	kW
UPS per-module load	`upsModuleKw()`	925.0	kW
Water makeup flow	`waterFlowLpmForWue()`	37.0	L/min
Carbon emission rate	`carbonKgPerHr()`	1 126.7	kgCO₂/hr
Usable fuel	`fuelUsableL()`	45 900	L
Fuel autonomy	`fuelAutonomyHr()`	48.0	hr

Accuracy rule 2: None of these values involves Math.random(). Every number is stable on reload, reproducible in Node, and verifiable against tools/test-conv-calc.mjs (22/22 DoD identities).

05 Outputs & cockpit panels

The cockpit surfaces these derived quantities across its dashboard, EPMS, cooling, water, fuel, and sustainability panels. Each KPI carries a basis chip citing its source.

KPI	CONV_CALC function	Unit	Panel
IT load	`model.site.it_load_kw`	kW	Energy dashboard
Facility load	`facilityLoadKw()`	kW	Energy dashboard / EPMS total
Non-IT load	`nonItLoadKw()`	kW	Energy breakdown
PUE	Facility / IT (identity)	—	Sustainability header
WUE	`model.environment.wue_l_per_kwh`	L/kWh	Sustainability / water panel
CUE (IT-basis)	grid factor × PUE	kgCO₂/kWh-IT	Sustainability panel
Carbon rate	`carbonKgPerHr()`	kgCO₂/hr	Sustainability panel
UPS loss	`upsLossKw()`	kW	EPMS electrical panel
UPS per-module kW	`upsModuleKw()`	kW	EPMS UPS A / UPS B gauges
CHW supply / return	`model.cooling.chws_c / chwr_c`	°C	Cooling panel — primary loop only
CHW ΔT	`chwDeltaT()`	K	Cooling panel
CHW flow	`chwFlowLps()`	L/s	Cooling panel
Heat rejection	`heatRejectionKw()`	kW	Cooling sanity band
Chillers running / total	`model.cooling.chillers_*`	—	Cooling panel status
Water makeup flow	`waterFlowLpmForWue()`	L/min	Water panel
Fuel level / usable	`model.fuel.level_pct / fuelUsableL()`	% / L	Fuel panel gauge
Fuel autonomy	`fuelAutonomyHr()`	hr	Fuel panel — 48 hr design target
Active racks (3 densities)	`activeRacks(m, kW)`	count	IT capacity panel
Avg temperature / RH	`model.environment.avg_temp_c / avg_rh_pct`	°C / %	Environment panel
EPMS metering tolerance	`model.electrical.metering_tolerance_pct`	%	EPMS quality chip

06 Worked example — 1 850 kW scenario

Full derivation chain reproducing every primary KPI on the live cockpit exactly. All figures match CONV_CALC.snapshot.

Facility load: 1 850 × 1.45 = 2 682.5 kW
Non-IT load: 2 682.5 − 1 850 = 832.5 kW
PUE reconciliation: 2 682.5 / 1 850 = 1.45 ✓ (identity holds)
UPS loss: 1 850 × (1/0.96 − 1) = 77.1 kW · per module (2N): 1 850 / 2 = 925.0 kW
CHW ΔT: 14.8 − 7.2 = 7.6 K · CHW flow: 1 850 / (4.186 × 7.6) = 58.1 L/s
Heat rejection: 1 850 + 77.1 = 1 927.1 kW — within design band 1 850–1 950 kW ✓
WUE check: 1.20 L/kWh (basis) · instant makeup flow: (1.20 × 1 850) / 60 = 37.0 L/min
Carbon rate: 2 682.5 × 0.42 = 1 126.7 kgCO₂/hr · CUE (IT-basis): 0.42 × 1.45 = 0.609 kgCO₂/kWh-IT
Usable fuel: 60 000 × 0.90 × 0.85 = 45 900 L · Autonomy: 45 900 / 956 = 48.0 hr ✓ (Uptime Tier III/IV target)
Active racks at 8 kW/rack: 1 850 / 8 = 231 racks

Engineering reading: the cockpit operates at 92.5% of design IT capacity (1 850/2 000 kW). PUE 1.45 is consistent with a mid-efficiency conventional chilled-water site (ASHRAE 90.1 baseline for the climate zone). The 48 hr fuel autonomy is the Uptime Institute minimum for uninterrupted Tier III/IV operations without refuelling.

07 References & standards

conv review doc 09 — 09-engineering-basis-and-calculations.md: primary source for all scenario constants (IT load, PUE, WUE, CHW loop, UPS efficiency, fuel system). Line numbers cited throughout.
ASHRAE 90.1 — Energy Standard for Buildings: PUE benchmarks and baseline cooling-system design parameters for conventional chilled-water data centres.
ASHRAE TC9.9 — Thermal Guidelines for Data Processing Environments: cold-aisle temperature and RH recommended bands (A1/A2 class).
Uptime Institute Tier Standard — Operational Sustainability (2021): 48 hr fuel autonomy requirement for Tier III/IV maintained availability.
ISO/IEC 30134-2 — Key Performance Indicators for Data Centres — Part 2: Power Usage Effectiveness (PUE) and Water Usage Effectiveness (WUE) definitions.
ISO/IEC 30134-8 — Key Performance Indicators for Data Centres — Part 8: Carbon Usage Effectiveness (CUE). Denominator = IT energy; grid carbon factor applied at facility-energy basis per doc-09 line 14.
Engine source — js/conv-engine.js (CONV_CALC v1.0.0 + CONV_MODEL, deep-frozen). Gate: tools/test-conv-calc.mjs (22/22 DoD identities).
Accuracy gate — tools/probe-accuracy-validation.mjs (40/40 acceptance tests, 6 accuracy rules). Must pass before any cockpit change ships.

08 Assumptions & limitations

The cockpit models a single fixed engineering scenario. It is not a design calculator and cannot be parameterised. Key assumptions and scope boundaries:

CHW loop: Only the primary (secondary) chilled-water loop at 7.2/14.8 °C is surfaced. The condenser-side loop operating at ~19–23 °C is out of scope for this cockpit and is never labelled CHWS/CHWR (conv-engine.js CHW basis decision). Secondary pump losses and free-cooling economiser modes are not modelled.

UPS topology: The 2N model assumes equal load sharing across both modules at 925 kW each. Single-module fault scenarios and static bypass paths are not modelled.

Fuel consumption: 956 L/hr is the generator consumption at approximately 2.7 MW facility load (generator output ≈ non-IT + IT generation, accounting for prime-move fuel burn curve). It is an engineering estimate for sizing, not a live meter reading.

WUE and water flow: The 37 L/min figure is the steady-state equivalent evaporative makeup rate derived from the annual WUE target. Actual instantaneous cooling-tower blowdown, drift loss, and basin makeup vary with ambient wet-bulb temperature. This cockpit displays the design-point equivalent only.

Carbon intensity: 0.42 kgCO₂/kWh is a fixed grid-average factor from the engineering basis. Real-time grid decarbonisation, marginal emissions, and Scope 2 market-based accounting are out of scope.

This manual and the cockpit are an engineering education and operational reference aid. They do not substitute for a live DCIM/EPMS/BMS with calibrated sensors, metered telemetry, and alarm setpoints set by a qualified controls engineer to the site authority having jurisdiction.