Technical Manual · Cockpit Basis
Data Hall SCADA Console — Methodology & Formulas
Every basis parameter, derivation, constant, KPI output, and reference behind the conventional SCADA cockpit. Current operation derives from the deep-frozen CONV_CALC snapshot; the separate Hall A–D capacity context derives from RZConvDesignBasis.STUDY. Neither authority is mutated by the selector.
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.
Current versus study: the current rack field remains the frozen 1,850 kW / 200-cell Hall A training snapshot (9.25 kW/cell average). The governed planning study is four 10 MW IT halls with 500 racks/hall at 20 kW/rack average. Its Hall selector is view-only. The study uses 25.4 °C as a project rack-inlet target inside the ASHRAE recommended 18–27 °C envelope; it does not relabel CRAH discharge air, current cold-aisle temperature or CHW temperature.
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 | Project operating basis. ASHRAE equipment guidance is class/dew-point dependent; 40–60% is not presented as a universal standard. |
| 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; ISO/IEC 30134-9:2022 reporting context | Project/model value with IT-energy denominator; no universal “good” grade is asserted. |
| 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: PUE 1.45, WUE 1.20 L/kWh and 48-hour fuel autonomy are declared project/model values. This cockpit does not assign them a universal “good” grade or claim that a particular fuel duration proves an Uptime Tier. The owner’s risk policy, utility reliability, delivery contract, load-dependent generator curve and certification authority govern any operational target.
07 References & standards
- ASHRAE Handbook — Data Centers and Telecommunication Facilities — rack-inlet recommended dry-bulb envelope (18–27 °C for the applicable A classes) and class/dew-point-dependent humidity guidance. The project 25.4 °C target and 48% RH basis remain site decisions.
- Uptime Institute Tier Standard — topology and concurrently-maintainable intent. No certification, universal fuel-duration target or WUE grading band is inferred by this cockpit.
- 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.
09 Cockpit workflow & telemetry-point map
The console is a deterministic teaching SCADA, not a live BMS endpoint. Read it top-down: alarm strip, engineering roll-up, balance band, selected heat-map layer, equipment inspector, then event log. Every value below maps to a concrete DOM binding or CONV_CALC.snapshot field.
| Signal / control | ID or binding | Unit / state | Normal interpretation | Source binding |
|---|---|---|---|---|
| Hall state | dh-hall-state | NORMAL / WARNING / CRITICAL | Worst active alarm severity. | Deterministic alarms[] aggregation in datahall.html. |
| Rack IT load | dh-rack-load, bb-itload | MW | 1.850 MW at the locked site/hall scope. | CONV_CALC.snapshot.site.it_load_kw. |
| Rack count / average | bb-racks, bb-avg | count, kW/rack | 200 displayed cells; average 9.25 kW/rack. | TOTAL_RACKS; IT kW ÷ rack count. |
| Power density | dh-pd | kW/rack | Same denominator as average rack load. | site.it_kw / datahall.racks_total. |
| PUE | dh-pue | ratio | 1.45 measured-basis value; not a target. | CONV_CALC.snapshot.site.pue. |
| Cooling margin | dh-cooling-margin, bb-cool | %, kW | Available running CRAH capacity minus IT sensible demand. | 17 running × 130 kW − 1,850 kW. |
| Cooling N+1 | bb-np1 | PASS / FAIL | One running CRAH may be lost and capacity still covers demand. | 16 × 130 kW ≥ 1,850 kW. |
| CHW plant | ch1..ch3, chws, chwr, chdt, chflow | state, °C, L/s | Two chillers run, one standby; temperatures and flow come from the frozen conventional scenario. | CONV_CALC.snapshot.cooling. |
| Alarm roll-up | as-crit, as-warn, as-maint | count | Rack and cold-aisle threshold breaches; maintenance equals standby CRAHs. | alarms[]; 20 total − 17 running. |
| Data health | as-comms, as-update, as-dq, as-scn | OK / timestamp / GOOD / Simulated | Declares freshness and provenance; does not imply a field connection. | Page clock plus static simulated-mode declaration. |
| Heat-map modes | mode-btn[data-mode] | power / temp / cooling-margin / alarms / space | One semantic layer at a time; selection is mirrored to the BMS layer toolbar. | setMode() and rackFill(). |
| Rack / CRAH inspector | sel-detail, crahPop | tagged detail | Hover/click exposes source, utilization, zone, temperatures and unit state. | Stable rack hash, zone aggregates and crahUnits[]. |
10 Spatial model, cooling balance & alarm logic
The rack field deliberately separates deterministic basis data from the temporary excursion simulator. Reloading produces the same occupancy, rack loads and normal cold-aisle temperatures; only an explicit excursion may introduce bounded short-lived variation.
rackTotal = Σ occupiedRackWeight × (1,850 kW / Σ occupiedRackWeight) = 1,850 kW
rackUtilization = rack_kW / 15 kW rating
coolingAvailable = 17 × 130 = 2,210 kW
coolingHeadroom = 2,210 − 1,850 = 360 kW
N+1 available = (17 − 1) × 130 = 2,080 kW ≥ 1,850 kW → PASS
zoneAirflow = (1,850 / 10) / ((1.2 × 1.006) × 11) m³/s
The fixed integer hash chooses roughly 8% spare cells and bounded occupied weights, then a normalization and residual correction force the exact EPMS reconciliation total. datahall.html rack model · CONV_CALC.snapshot
| Condition | Normal | Warning | Critical / alarm | Visual meaning |
|---|---|---|---|---|
| Rack utilization | <70% | 70–85%; 85–95% elevated tiers | >95% rating | Green → amber/orange → fault red; spare is muted. |
| Cold-aisle temperature | <26°C; displayed normal baseline ≈22.0°C ±0.3°C deterministic | >26°C | >30°C | Temperature layer and alarm list share the same thresholds. |
| CRAH availability | 17 RUN / 3 STBY | Loss of redundancy | Post-failure capacity below 1,850 kW | N+1 chip reports the capacity comparison, not a decorative state. |
| Communications / quality | OK / GOOD | Stale or degraded when implemented | Unavailable when implemented | Current page is simulated and does not poll a live transport. |
Excursion boundary:
fireExcursion() uses bounded Math.random() only for an explicitly simulated 10–15 second zone/CRAH excursion. It does not alter the locked 1,850 kW, PUE, rack-reconciliation, plant basis or normal deterministic layout. Evidence must distinguish this training transient from measured telemetry.11 Glossary, operating sequence & limitations
CRAH, PUE, WUE, N+1 and EPMS terms are exposed to RZExplain. These definitions describe the cockpit model and must not be mistaken for site commissioning set-points.
| Term | Meaning in this cockpit | Operator action |
|---|---|---|
| EPMS reconciliation | Rack-field sum compared with UPS-output IT kW from the same frozen engine snapshot. | Investigate any non-zero balance before trusting downstream density or cooling calculations. |
| Cold aisle | Rack inlet-side air zone; normal training baseline is approximately 22°C. | Select Temperature, locate the hottest zone, then inspect assigned CRAHs and rack load. |
| Cooling margin | Running sensible cooling capacity minus modelled hall IT heat. | Confirm N+1 remains positive; margin alone is not proof of correct airflow distribution. |
| Standby / maintenance | Three installed CRAHs outside the 17-unit running set. | Verify availability before taking another unit out of service. |
| Simulated data | Local deterministic model plus explicit training excursions; no BMS/SCADA transport. | Use for education and pre-design review only; validate against field sensors and approved sequences. |
- Read the alarm strip and data-quality/scenario chips before interpreting numbers.
- Confirm rack-field total balances to EPMS IT load and cooling N+1 passes.
- Select one semantic mode, locate the affected zone, then inspect its rack or CRAH.
- Use the event log as a training trace; use an actual alarm historian for operational diagnosis.