1,800 kWh/month of Standby Consumption Revealed
A large sheet-metal processing machine was used for production only occasionally. There had been an ongoing debate between the production manager and the energy specialist about how much keeping the machine continuously on standby was actually adding to the electricity bill.
Without measurement data, there was no objective answer.
Submetering changed that.
The data showed that even when the machine was not producing, it continuously drew approximately 3 kW of electrical power.
This consumption was caused by maintaining the temperature of the machine’s oil and cooling water.
Over a month, this amounted to approximately 1,800 kWh of electricity, accounting for nearly half of the machine’s total energy consumption during the period analysed.
The starting point
The equipment under investigation was a high-power sheet-metal processing machine that was not used continuously.
Actual production periods were easy to identify in the measurement data, with power peaks exceeding 50 kW.
However, the machine did not completely shut down between production periods.
This raised an important question:
How much energy does a high-power machine consume when it is not actually producing anything?
What did we measure?
Using the submetering system, we continuously monitored the machine’s electrical power consumption.
Alongside the production periods, the data clearly showed a constant base load of approximately:
3 kW.
This was not a standby condition lasting only a few minutes.
The consumption continued for hours and days at a time, even when the machine was performing no productive work.
What did submetering reveal? image
The chart clearly shows two very different operating states.
The large peaks above 75 kW indicate periods when the machine was actively operating.
Between these production periods, however, consumption did not fall to zero.
Instead, a continuous power draw of approximately 3 kW remained visible.
And that was the important part.
The problem was not the short periods of high power demand.
It was the consumption that continued unnoticed for long periods of time.
What was causing the standby consumption?
While on standby, the machine continuously maintained the temperature of:
the machine oil;
and the cooling water.
The purpose was to keep the equipment in a condition where it could be ready for operation when required.
From an energy perspective, however, this meant that a rarely used machine continued consuming electricity even when it was not producing anything.
Was continuous standby really necessary?
This became one of the most important questions raised by the measurements.
We also examined what happened after the machine was completely shut down.
The experience showed that even after a full shutdown, the machine could be returned to an operational condition within one day.
This meant that keeping a rarely used machine continuously at operating temperature for weeks at a time was not necessarily justified.
What could have been changed?
Once again, the solution would not have required new equipment or a major energy-efficiency investment.
The key issue was production planning and operational scheduling.
By grouping production tasks more effectively, the machine could have been used intensively when required and then completely shut down during longer periods of inactivity.
This would allow the equipment to remain temperature-controlled only when there was a genuine operational need.
The result
Based on the measurement data, the machine’s standby consumption was approximately:
1,800 kWh/month
According to the original analysis, nearly 50% of the machine’s total electricity consumption during the period examined was attributable to maintaining operating temperature.
This was far from insignificant.
Nearly half of the machine’s electricity consumption occurred while it was not producing anything.
In this case, the potential saving could have been achieved through improved production scheduling and by reducing unnecessary standby periods.
What does this case show?
It is not enough to analyse a machine’s energy consumption only while it is producing.
In many cases, an equally important question is:
How much does it consume when it is doing nothing?
A continuous 3 kW base load may not sound particularly significant at first.
But when it continues 24 hours a day for weeks at a time, it adds up to substantial energy consumption.
This is exactly the kind of long-term hidden consumption that submetering can make visible.
Do you know how much your machines consume when they are not producing?
Submetering can separate actual production energy demand from standby consumption and other background loads.