Energy Intensity Calculator (kWh per Unit, per m2, per Revenue)
Energy intensity is the metric behind most plant energy targets and ISO 50001 energy performance indicators: how much energy it takes to make one unit, or to run one square metre. This calculator puts electricity, gas and other fuels on one basis and shows the ratio.
Your numbers
1 therm is about 29.3 kWh of energy content.
Convert other fuels to gigajoules using their heating value.
Your results
Intensity is only comparable when the energy boundary, output measure and period are the same. Weather and product mix can shift it without any efficiency change.
kWh per unit vs production volume
Sweeps Production output from 100000 to 400000, holding your other inputs fixed.
Report energy per work centre from the ERP
Optional: see how meter readings and production orders can be combined into a live intensity dashboard.
Optional. The tool and every export work without this. No spam.
How to use it
Enter a month or a year of electricity, natural gas and any other fuel. Put the output in the units you plan, whether pieces, tonnes or machine hours, then add floor area and revenue if you want the other two ratios. The tool converts everything to kWh and gigajoules, and the sweep chart shows how intensity falls as volume rises because baseload energy gets spread across more output.
- Use the same boundary every period
- Choose one output measure and keep it
- Add submeter data when you need process detail
- Compare against the same season in prior years
The method behind it
Total energy is the sum of every carrier converted to a common unit. Natural gas at about 29.3 kWh per therm and gigajoules at 277.78 kWh per GJ are used here. Specific energy consumption is total energy divided by output. ISO 50001 expects you to establish an energy baseline and track performance indicators like this, normalising for relevant variables such as production volume and weather before claiming improvement.
Reading the result
A high kWh per unit alongside a low volume usually means fixed load: compressed air leaks, idle machines, lighting and HVAC running over empty shifts. If the chart is steep, raising throughput or shutting down idle equipment will help more than process upgrades. A rising kWh per square metre with flat volume points to building services. Compare with sites of similar process rather than with a generic benchmark.
Common mistakes
Mistakes include comparing a month with a holiday shutdown to a full month, dividing by sales dollars when prices changed, leaving out purchased steam or compressed air, and mixing gross and net floor area. Always state what the denominator is so the number can be reproduced. When claiming savings, adjust for volume and weather rather than comparing raw totals.
Frequently Asked Questions
What is energy intensity?
It is energy consumed divided by a measure of activity, such as units produced, floor area or revenue. It lets you compare performance across months, lines or plants of different size.
How do I convert therms to kWh?
One therm is 100,000 Btu, which equals about 29.3 kWh. For gigajoules, multiply kWh by 0.0036. Gas bills in cubic metres need the supplier's calorific value to convert.
Which denominator should I choose?
Choose the one that best tracks what drives energy in your plant. Units or tonnes suit process-heavy sites, floor area suits offices and warehouses, and revenue suits corporate reporting but is sensitive to price changes.
Does this satisfy ISO 50001?
It gives you an energy performance indicator, which is part of ISO 50001. The standard also requires a baseline, normalisation, objectives and management review, so use this as a building block.
Netray can join utility meter data with production output from your ERP so energy intensity is reported per work centre and per product automatically.
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