Calculator Inputs
Example Data Table
| Case | Baseline (kWh) | Improved (kWh) | Output | Input (kWh) | Useful (kWh) | Savings (%) | Efficiency (%) |
|---|---|---|---|---|---|---|---|
| Compressed air leak fix | 12,500 | 9,850 | 40,000 unit | 9,850 | 6,800 | 21.20 | 69.04 |
| Motor + VFD upgrade | 8,100 | 6,300 | 12,000 unit | 6,300 | 4,900 | 22.22 | 77.78 |
| Boiler tuning | 25,000 | 22,400 | 500 ton | 22,400 | 16,800 | 10.40 | 75.00 |
Formula Used
How to Use This Calculator
- Measure baseline energy for a consistent operating period.
- Measure improved energy under the same output conditions.
- Enter service output and a clear unit label.
- Enter system energy input and useful output energy.
- Optionally add cost per kWh and emissions factor.
- Press Calculate and review the summary above.
- Download CSV for spreadsheets or PDF for sharing.
Engineering Notes
Energy intensity benchmarks
Energy efficiency is commonly tracked as a percentage and as energy intensity. In plant audits, intensity often ranges from 0.15 to 2.50 kWh per unit, depending on process type, automation, and duty cycle. This calculator reports both baseline and improved intensity, helping normalize energy use when output changes. A 10% intensity reduction usually signals meaningful operational improvement when production quality, scrap rate, and uptime are stable. Record meter accuracy and sampling interval to keep comparisons defensible.
Comparable operating conditions
Baseline and improved energy should cover the same boundary and operating hours. For engineered systems, compare equivalent load profiles, ambient conditions, and control settings. If a baseline month uses 12,500 kWh and the improved month uses 9,850 kWh, savings equal 2,650 kWh and 21.2%. That percentage is useful for stakeholders, while absolute kWh drives cost, capacity relief, and emissions estimates. When output differs, intensity is the safer KPI for decision making.
Conversion efficiency and losses
System efficiency focuses on conversion from input energy to useful output energy. Typical ranges vary: electric motors often exceed 85%, industrial boilers can sit between 75% and 90%, and compressed air systems may deliver under 20% end‑use efficiency. Entering input and useful output highlights losses, guiding maintenance priorities such as insulation, leakage control, tuning, lubrication, filter replacement, and right‑sizing. Large losses often indicate avoidable heat, friction, or throttling.
Financial impact with tariffs
Cost savings are estimated by multiplying saved kWh by the tariff. With a 0.18 cost per kWh, 2,650 kWh saved equals 477.00 in savings for the measured period. For time‑of‑use billing, run the calculator separately for peak and off‑peak intervals, then combine results. Add demand charges as a separate analysis if improvements reduce peak kW. Use the same currency unit across reports to prevent confusion.
Emissions reporting and exports
Emissions avoidance depends on an emissions factor in kg CO2e per kWh. Factors vary by region, fuel mix, and season, so use your published utility or national value when available. Using 0.45 kg/kWh, saving 2,650 kWh avoids about 1,192.5 kg CO2e. Export CSV or PDF to attach transparent calculations to audits, ISO reports, and engineering change requests. Keep factors and assumptions in the file for future verification. For portfolios, standardize the factor and period to compare projects fairly across sites.
FAQs
1) What does “energy intensity” mean?
Energy intensity is energy used per unit of service output. It helps compare performance when production volume changes, using kWh divided by units, tons, hours, or another consistent output measure.
2) Why do I enter both improved energy and system input energy?
Improved energy supports savings versus baseline. System input energy is used to compute conversion efficiency against useful output. They can match, but audits sometimes use different measurement boundaries.
3) How should I estimate useful output energy?
Use metered delivered energy when available, or calculate useful work from process measurements and equipment specifications. Keep assumptions documented, and avoid mixing theoretical output with measured input when possible.
4) Can I use this for HVAC, motors, or process lines?
Yes. Any system with baseline and improved energy plus a measurable output can be analyzed. Choose an output unit that reflects delivered service, such as cooling ton-hours, m³ pumped, or units produced.
5) What emissions factor should I use?
Use your local grid or fuel factor in kg CO2e per kWh from a utility, regulator, or verified report. If you track market-based factors, keep a separate record for consistency.
6) Why is my efficiency rating lower than my savings percent?
Savings percent compares baseline to improved energy. Efficiency describes how much input becomes useful output, which can remain low even after reductions. Both metrics together indicate where optimization is most valuable.