Energy Meter Allocation per Good Kilogram or Metre

The formula

This is the expression the tool evaluates. Every term is named underneath, with the unit it must be supplied in.

How the result is derived

Step by step, from the values you type to the figure on screen.

1. The 11 inputs are read from the form on every keystroke: Electricity Imported, Direct-Fired Process Gas, Steam Delivered to Process, Heat Content of the Steam, Boiler House to Process Efficiency, Compressed Air Delivered, Compressor Specific Power, Output Processed, Output Not Saleable, Fabric Mass per Metre and Energy in Non-Production Hours.
2. Each value is checked against the accepted range in the input table below. A value outside its range stops the calculation rather than producing a misleading figure — the results blank out and a message appears.
3. The validated values are substituted into the expression above, which resolves Energy per Good Kilogram together with every supporting figure in one pass — no value is carried over from a previous entry.
4. The supporting outputs — Energy per Kilogram Processed (the shortcut), Energy per Good Metre, Production-Related Energy per Good Kilogram, Site Energy at the Fuel Boundary, Energy Carried Out by Scrap, Site Energy That Made Nothing Saleable, Boiler House & Steam Main Loss and Compressed Air Share of the Electricity Meter — come from the same pass, so they always describe the same case as the headline figure.
5. Results are rounded for display only. The full-precision value is used throughout the chain, so reading a rounded intermediate figure back into the tool by hand can shift the last digit.

What each input means

Where to read each value on the floor, the unit it must be in, and the range the tool accepts.

What the tool returns

The headline figure and every supporting value it is built from.

Worked example

Substituting

The plant quotes 5.2484 kWh/kg, because that is the meters divided by the production report. The figure it owes its customers and its own baseline is 5.4658 kWh/kg, and the 4.1 per cent between them is 7,400 kg of fabric that was scoured, dyed, dried and finished at full energy cost and then sold as waste. Two further numbers reorder the whole improvement plan. The compressed air system, which the last audit called twenty per cent of the load, is 20.4206 per cent of the electricity meter but only 4.48 per cent of site energy. The boiler house and steam mains lose 102995.122 kWh, or 10.55 per cent - two and a third times the entire air system, and on most sites the only one of the two nobody has metered.

How to use it

1. Work through the input groups in order — Plant Meters for the Period, Conversion Losses & Sub-Meters and Output, Losses & Standby. The defaults are a realistic case, so you can change one value at a time and watch what moves.
2. There is no calculate button. Every figure recalculates as you type or drag, which is what makes this usable for a what-if sweep rather than a single answer.
3. Read Energy per Good Kilogram in the dark results panel — that is the headline figure, expressed in kWh/kg.
4. Check the supporting rows underneath (Energy per Kilogram Processed (the shortcut), Energy per Good Metre, Production-Related Energy per Good Kilogram, Site Energy at the Fuel Boundary, Energy Carried Out by Scrap, Site Energy That Made Nothing Saleable, Boiler House & Steam Main Loss and Compressed Air Share of the Electricity Meter) before acting on the headline — they are where an implausible input usually shows itself first.
5. Reset to defaults returns every field to the reference case, which is the quickest way to check whether a surprising result came from the tool or from an input you had changed earlier.

Where this is used

• Process planning — establishing Energy per Good Kilogram before a trial is booked, so machine time and material in Quality Systems, Traceability, Utilities & Factory Decisions are committed against a calculated figure rather than an estimate.
• Costing and quotation — Energy per Good Kilogram is an input to the cost sheet, and quoting from a worked number rather than a remembered one is what keeps a margin intact.
• Troubleshooting — when the floor result drifts from plan, entering the measured values (starting with Electricity Imported) shows how much of the gap in Energy per Good Kilogram each variable explains.
• Teaching and study — the accepted ranges bracket normal Quality Systems, Traceability, Utilities & Factory Decisions practice, so moving one variable at a time shows the shape of the relationship rather than a single answer.

Reading the result

Typical bands and what each one is telling you.

Assumptions and limits

• Allocation here is by mass at average intensity, which is a deliberate simplification with two known biases. Fabric rejected at final inspection carried the full process energy, while fabric pulled at grey inspection carried almost none, so a mass-weighted scrap charge is an upper bound when rejects are found early and an underestimate when they are found late; if your rejection point is known, weight the scrap by the fraction of the route it completed. Product mix cuts the same way, because a heavy navy at long liquor ratio can take twice the energy per kilogram of a pale continuous run, so mass allocation quietly subsidises the difficult product. The compressed air figure is a sub-meter of electricity and must never be added to the site total; the tool reports it as a share for exactly that reason. Direct-fired gas must exclude boiler fuel, which is reconstructed from the steam and efficiency figures instead. Boiler efficiency is intended as a boiler-house-to-process figure covering flue, blowdown, standing and distribution loss on the same calorific-value basis as the gas bill - a net-basis efficiency against a gross-basis bill overstates performance by about ten per cent for natural gas. Steam heat per tonne must match the working pressure and the real feedwater temperature; the 680 kWh/t default corresponds to saturated steam near 8 bar g from 85 deg C feedwater with no condensate return credit, and a site returning hot condensate should lower it. Standby energy is usually estimated rather than metered, read off the half-hourly profile floor, and it is the input most worth improving. The per-metre result is only meaningful for a single fabric construction, since it is simply the per-kilogram figure multiplied by mass per metre. Finally, this is a plant-boundary allocation tool and not a machine study: it will tell you how much of the site bill made nothing saleable, but it cannot tell you which machine spent it.
• Every input is bounded to the range normal practice occupies (Electricity Imported 100 to 50000000 kWh, Direct-Fired Process Gas 0 to 50000000 kWh and Steam Delivered to Process 0 to 100000 t, and so on for the rest). Those bounds are guard rails against typing errors, not a claim that the formula fails one unit outside them.
• The calculation is deterministic: the same inputs always give the same result. It carries no allowance for machine condition, operator skill, ambient conditions or lot-to-lot material variation unless an input above explicitly represents one.
• Nothing is sent anywhere. The maths runs in your browser, so the numbers you type never leave the page.

Standards and further reading

• ISO 50001:2018 - Energy management systems, requirements with guidance for use. Clause 6.4 requires energy performance indicators appropriate for measuring energy performance, clause 6.5 requires an energy baseline on the same basis, and clause 9.1.1 requires the two to remain comparable when they are monitored.
• ISO 50006 - Evaluating energy performance using energy performance indicators and energy baselines. This is where the boundary, the relevant variable and the normalisation of a specific-energy figure against production are defined.
• ISO 50015:2014 - Measurement and verification of energy performance of organizations, general principles and guidance, which governs how a claimed saving is proved against a baseline period rather than asserted from two monthly numbers.
• EN 12953-11 for shell boiler acceptance tests and ISO 1217 for displacement compressor acceptance tests, including free air delivery and specific power. These give the boiler efficiency and compressed air figures entered here a measurable meaning rather than a nameplate one.

Questions people ask