When considering the purchase of a new digital-printing press, it is important to show customers its energy efficiency capabilities. The ISO 20690 standard – primarily developed by Fogra – shows that like-for-like comparison is the way forward.
2024
HOW TO MEASURE THE ENERGY EFFICIENCY OF DIGITAL-PRINTING MACHINERY
Company
Fogra Research Institute for Media Technologies
Dr Andreas Kraushaar of Fogra Research Institute for Media Technologies, explores the ISO 20690 standard and how it can make accurate and verifiable consumption data widely available to the digital-printing industry
Dr Andreas Kraushaar, Head of Prepress Technology at Fogra Research Institute for Media Technologies
Dr Andreas Kraushaar, Head of Prepress Technology at Fogra Research Institute for Media Technologies
WHY COMPARE?
With the ISO 20690 standard, press buyers, printers and their customers can objectively assess the energy efficiency of digital-printing presses.
Energy consumption is an essential component of all performance requirements and quality standards. It is essential to maintain the required quality and repeatability. Energy efficiency is always expressed as a ratio of printed area (m²) to energy consumed (kWh). This information can be used to assess the power consumption and energy efficiency of presses, including peripherals. It can also estimate operating costs for investment planning and benchmark the energy efficiency of digital-printing presses. Additionally, it can measure how energy efficiency increases over time or for dedicated process variations. Finally, data can be provided to enable companies to claim environmental subsidies when upgrading to more energy-efficient equipment.
ISO 20690 cannot be used to determine the power consumption of individual equipment components such as servo motors, fans, compressors and control boards.
“It is essential to maintain the required quality and repeatability”
HOW TO MEASURE
Measurement can be achieved via qualified power meters that measure voltage and current every second. The press is controlled, even when it is switched off. For example, energy is also required if the printheads circulate because it activates the print standby mode.
A specified print job must be printed – after defined minimum times – at least twice for five minutes or longer in the predefined machine configurations. For example, ‘best quality’ (BQ) or ‘best productivity’ (BP). If the energy efficiency of the two measurement cycles is not within five per cent of each other, another print is required. After all printing conditions have been run through, the press is put into sleep mode and then switched off.
In practice, not every digital-printing press supports all predefined operating states. Additional states – such as a maintenance mode – are sometimes offered. This must be clarified before implementation.
Figure 1: The three phases’ power consumption in Watts (W), L1, L2, and L3, as well as the apparent power (red) and the total power (L1+L2+L3, green). The arrows and letters (A to E) indicate the machine configurations analysed
Figure 1: The three phases’ power consumption in Watts (W), L1, L2, and L3, as well as the apparent power (red) and the total power (L1+L2+L3, green). The arrows and letters (A to E) indicate the machine configurations analysed
DISTINCTION OF OPERATING MODES
A distinction needs to be made between operating states – BQ, BP and so on – and those without print production (‘off’, ‘sleep’, “print ready’, etc). Efficiency can only be calculated in the first case as there is only a concrete, measurable output – the printed area. The average power consumption – including the scatter – is specified in the second case.
“The resulting efficiencies of 55m2/kWh (BQ/BP-1) and 57m2/kWh (BP1) are almost identical”
Figure 2: Power consumption in Kilowatts (kW) of the total output (L1+L2+L3, magenta). The coloured horizontal lines indicate the machine configurations examined
Figure 2: Power consumption in Kilowatts (kW) of the total output (L1+L2+L3, magenta). The coloured horizontal lines indicate the machine configurations examined
POWER CONSUMPTION
Figures 1 and 2 show the power consumption during the measurement cycle and the calculated key figures. These are the energy efficiency values for the selected press configurations and the average power consumption of the existing operating states.
Both figures show the same illustration for a high-speed inkjet printer. The power consumption is very different, but the energy efficiency is extremely similar. For example, the average power consumption of the web inkjet press is 100,000W (100kW) and the large-format printer is 1,500W (1.5kW). The resulting efficiencies of 55m2/kWh (BQ/BP-1) and 57m2/kWh (BP1) are almost identical.
“The knowledge gained can also improve the hardware and software used”
THE BENEFITS
Fogra’s extensive experience in implementing this measurement specification shows that the indicators are used very differently. On the one hand, the development of a printing press is supported, particularly in determining its own position in relation to the competition. The knowledge gained can also improve the hardware and software used. On the other hand, the data is included in the product data sheet. In this way, the company can clearly communicate its sustainability.
The data collected by Fogra makes it possible to compare the efficiencies achieved with other standard industrial presses. If the efficiency is 80% higher than the average for a comparable press configuration, Fogra grants an energy efficiency label (FograCert Energy Efficiency).
“ISO 20690 is the first practical and standardised method for determining energy efficiency”
Figure 4: The parameters determined for a high-speed inkjet corrugated printing machine
Figure 3: The parameters determined for an exemplary large format printer
Figure 4: The parameters determined for a high-speed inkjet corrugated printing machine
Figure 3: The parameters determined for an exemplary large format printer
CONCLUSION
This example of energy efficiency shows that Fogra’s practical research pays off. The resulting standard proposal led to ISO 20690. It is the first practical and standardised method for determining energy efficiency. The assessment is of interest to manufacturers and print-service providers.
It should be taken into account in any new investment decision. With high energy prices, choosing energy-efficient presses can significantly reduce costs.
Ultimately, the key figures also allow an exact estimation of the expected annual electricity costs for different operating processes and press use levels.