Calculator Inputs
Example Data Table
| Scenario | Racks | Avg Rack kW | Util % | PUE | Redundancy | PF | Voltage / Phase | Facility kW | Design kW | Design kVA |
|---|---|---|---|---|---|---|---|---|---|---|
| Colocation hall (typical) | 40 | 6.0 | 65 | 1.45 | N+1 | 0.95 | 400 V / 3φ | ≈ 241.10 | ≈ 318.05 | ≈ 334.79 |
| High-density buildout | 30 | 12.0 | 70 | 1.35 | 2N | 0.97 | 480 V / 3φ | ≈ 354.00 | ≈ 814.20 | ≈ 839.38 |
| Small edge site | 6 | 4.0 | 55 | 1.60 | N | 0.92 | 230 V / 1φ | ≈ 21.12 | ≈ 24.29 | ≈ 26.40 |
Formula Used
- Base IT Load (kW): racks × average rack kW, or direct entry.
- Operating IT Load (kW): base IT load × utilization ÷ 100.
- Facility Load (kW): (operating IT load × PUE) + misc kW.
- Design Capacity (kW): facility kW × (1 + margin%) × redundancy factor.
- kVA: kVA = kW ÷ power factor.
- Current (A): 3-phase: I = (kVA × 1000) ÷ (√3 × V), 1-phase: I = (kVA × 1000) ÷ V
- Heat Rejection: BTU/hr = facility kW × 3412.142, tons = BTU/hr ÷ 12,000.
- Annual Energy: kWh/year = facility kW × average load fraction × hours/year.
How to Use This Calculator
- Select Calculation Mode and enter rack data or base IT load.
- Set Utilization to represent expected operating conditions.
- Enter PUE and any misc loads not captured by PUE.
- Choose a Redundancy strategy and add a realistic design margin.
- Provide power factor, voltage, and phase for kVA and current.
- Click Calculate to view results above the form and download reports.
Article
Load Planning Inputs
Accurate power planning starts with a clear IT baseline. This calculator supports rack-based estimating and direct IT entry, then applies utilization to reflect realistic operating conditions. Use utilization to separate “installed” from “expected” demand, especially when growth is staged. Add a small misc load to represent items outside the PUE scope, such as dedicated security systems or non-standard auxiliaries.
Translating IT to Facility Demand
PUE links IT power to total facility demand. The model uses facility kW = (operating IT kW × PUE) + misc kW, giving a fast planning value for utility and generator discussions. Lower PUE reduces total demand without changing IT capacity, so efficiency upgrades can be evaluated as a direct reduction in upstream kW and kVA.
Redundancy and Margin Strategy
Redundancy and design margin protect availability. The calculator applies margin for uncertainty and future growth, then multiplies by a redundancy factor for high-level sizing. For early concept work, this approach helps compare N, N+1, and 2N outcomes quickly and keeps capacity decisions traceable to the input assumptions.
Electrical Distribution Outputs
Feeder planning depends on apparent power and current. The tool converts kW to kVA using the selected power factor and estimates current from voltage and phase. This supports first-pass feeder sizing, switchboard planning, and UPS rating discussions. The UPS efficiency input also estimates upstream input kW to highlight losses that affect utility demand.
Cooling and Energy Implications
Nearly all electrical power becomes heat, so the calculator converts facility kW to BTU/hr and refrigeration tons for quick HVAC checks. Annual energy is estimated using an average load fraction and hours per year to support budgetary forecasting. Example data: 40 racks × 6.0 kW at 65% utilization gives 156 kW operating IT. With PUE 1.45 and 15 kW misc, facility demand is about 241 kW. With 15% margin and N+1, design capacity is about 318 kW, or roughly 335 kVA at PF 0.95.
FAQs
1) What is the difference between IT load and facility load?
IT load is the power used by computing equipment. Facility load includes IT plus supporting systems, such as cooling and power distribution losses, commonly represented through PUE and any added miscellaneous loads.
2) Why does utilization matter?
Installed capacity is rarely fully used all the time. Utilization adjusts the base IT load to a realistic operating level, improving estimates for utility demand, generator sizing, and typical cooling requirements.
3) What does PUE represent in this calculator?
PUE is the ratio of total facility power to IT power. The calculator multiplies operating IT kW by PUE to estimate facility kW, then adds any miscellaneous loads you specify.
4) How is N+1 handled here?
N+1 is represented with a generalized planning factor to approximate extra capacity. Use it for early concept comparisons, then refine using your preferred redundancy topology and manufacturer-specific loading limits.
5) Why do I need power factor?
Power factor converts real power (kW) to apparent power (kVA). Feeders, transformers, and switchgear are often constrained by kVA and current, so PF improves electrical sizing realism.
6) How is feeder current calculated?
The calculator estimates current from design kVA and voltage. For 3-phase, it uses I = (kVA×1000)/(√3×V). For single-phase, it uses I = (kVA×1000)/V.
7) Are the cooling tons exact?
Cooling is estimated from electric power-to-heat conversion, which is useful for quick checks. Final HVAC design should include airflow, humidity control, equipment placement, and diversity factors from your mechanical engineer.