Issue #0713/2 - Compliance is changed for all paper printer products to require testing to determine a typical electrical consumption over a period of time. Printer features and components help determine the exact compliance figure through a system of power allowances.
With regard to the tightening of the requirements of the new Energy Star as it relates to power consumption, the situation is not as straightforward and too much explanation probably will not be beneficial. So, we will focus on the key elements with brief description of what is required and apparent shortcomings.
Firstly, whereas the previous standard set limits on power consumption in the device’s power saving modes, particularly in sleep mode, the new standard is more focused on overall power consumption over time.
Where sleep mode specifically is concerned, power consumption for the new standard has been set at between 3 Watts and 6 Watts for most types of device. The exceptions to this are large format printers and MFPs, which are allowed to consume up to 58 Watts in sleep mode.
Fitting a Total Cost of Printing model much more closely that the original requirements, this new overall power consumption approach can, again, only help the overall energy consumption situation and must be regarded as significant progress.
Typical Electricity Consumption (TEC) is the resulting measurement criteria and is a metric that has been built into the CharisCo Printer Labs TCOIllustrator software for more than six years. Methods of calculating the estimated TEC will vary, of course, and the purpose of the new Energy Star standard is to define an actual test methodology for manufacturers to follow rather than leave it to modelling estimates.
Under the new Energy Star rules, the manufacturer must test the overall power consumption of each model for which it wants to obtain Energy Star compliance to arrive at a power consumption figure for Kilowatt-hours (kWh) per week under typical usage conditions.
Printers consume the most power when actually printing – all electronics, mechanics and heated fuser unit are in operation and consuming power.
Once the print job is completed, the printer maintains a state of readiness for a while because of the possibility that a new print job will be sent. In this stand-by state, power consumption is still relatively high, because the fuser is maintained at a high temperature to avoid an excessive warm-up time when a new print job is sent, but is not as high as during printing.
Stand-by readiness is maintained for a matter of a few minutes and can vary considerably depending on the approach to power reduction taken by the manufacturer. The length of time can generally be defined by the user within the device’s set-up menu and may typically vary from 5 minutes up to perhaps an hour.
If no print job is sent to the printer within the stand-by period, then the device slips into a sleep mode where all services are shut down except for monitoring services. Power consumption in sleep mode can therefore be very low because the device is only running a few items of electronics as it waits for another print job.
Once a new print job is sent, the printer then has to warm itself up again, heating the fuser up to full fusing temperature, at which point it can then print the job sent. This results in a delay of some seconds (length depending on printer type and brand) before the printer is operational.
Part of the Total Cost of Printing calculations undertaken by CharisCo Printer Labs makes an assumption regarding the number of print jobs that a specific monthly page throughput will represent and that the printer is set for a 15 minute stand-by period. The calculations then comprise: time taken actually printing; time spent in stand-by based on the above assumptions; and thus, time spent in sleep mode depending on the number of hours the machine is powered up in a day. The EPA and EU commission recognise that many devices are left powered up 24 hours a day.
So, we have the printer running at full power for a given number of minutes/hours each day, sitting in stand-by mode for 15 minutes after each print job and then sitting in sleep mode for the rest of the day – plus overnight.
In addition to the actual test results, allowances may be made for a built-in Digital Front End (DFE) that performs high level functions independently of the print engine while allowing the print engine to enter sleep mode. Integrated DFE units must offer at least three of the following functions:
- Network connectivity in various environments
- Mailbox functionality
- Job queue management
- Machine management (e.g., waking the imaging equipment from a reduced power state)
- Advanced graphic user-interface (UI)
- Ability to initiate communication with other host servers and client computers (e.g., scanning to email, polling remote mailboxes for jobs)
- Ability to post-process pages (e.g., reformatting pages prior to printing)
So, the manufacturer is able to deduct the power used by this digital front end from the total power used as an allowance for marketing a highly specified and sophisticated device. Simpler devices will therefore not benefit from the allowances.
Energy Star offers an example of a printer consuming 24.5kWh of electrical energy per week (under TEC testing). It has an internal digital front end (DFE) that consumes 50W when in ‘Stand-by’ or ‘Ready’ mode. Over a 168-hour week (24/7), the consumption is 8.4kWh. This figure is subtracted from the TEC figure of 24.5kWh, giving a final result of 16.1kWh – a figure that must fall within the guidelines laid down for Energy Star compliance.
In addition, the manufacturer can gain extra power allowances against power consumption for certain additional functions of a device, such as wireless network adapter and scan unit. Hence, the higher the sophistication of the device (the more functions it can perform with high power efficiency) the more likely it is that the device will be able to comply with the standard.
Liquid inkjet does not qualify for Energy Star under the TEC approach because inkjet printers have no fuser and, therefore, no high power consumption components.
Instead, liquid inkjet falls into the category of devices that must comply with Operational Mode (OM) criteria. This merely measures the power consumption of the device in its various operational modes, Printing/Stand-by/Sleep, much as before. In fact, it really only covers the consumption in low power modes, so power consumption during printing does not matter and already most manufacturers publish specifications only for sleep mode.
At this very simple level, Energy Star sets an upper limit for sleep power consumption of a device. Energy Star also sets an upper limit for power consumption by these ‘functional adders’ (additional hardware units that add functionality to the device), depending on whether they are primary or secondary functions.
Energy Star gives the example of an inkjet printer with USB interface as its standard interface that also has a memory card reader as an additional, and secondary, interface. The upper limit for the device in sleep mode is 3 Watts but the manufacturer can also include a 0.5 Watt allowance for the primary USB interface and a 0.1 Watt allowance for the secondary memory card interface. Thus, the upper limit for total power consumption in sleep mode for that printer is 3.6 Watts and, as long as the tested result is below 3.6 Watts, the printer complies with Energy Star.
Where the power consumption of a printer in stand-by mode already meets the requirements laid down for sleep mode compliance, the manufacturer doesn’t need to make any provision for a specific sleep mode to reduce power consumption even further.
Printing devices must have a maximum time delay of four hours on their preset sleep mode delay timer that the user cannot alter and must also have a default sleep mode delay time that does not exceed a limit specified by Energy Star. However, the user is typically able to alter this default setting.
For instance, a 60ppm MFP is allowed to have a default sleep delay time of 60 minutes while the sleep delay time for a 10ppm inkjet printer must not exceed 5 minutes.
Functional adders that attract an extra power allowance for Operational Mode compliance include: data interface; internal storage device; scanner; telephone handset; memory; and the power supply itself.
Interestingly, a GDI printer actually attracts a negative secondary adder allowance of half a Watt because the device has to rely on an external processing system (a PC) to undertake tasks normally undertaken within the printer itself.
There are also additional rules governing the maximum power consumption of devices using external (rather than integrated internal) power supplies and digital front ends and also fax capable devices that include additional cordless handsets.
In terms of undertaking testing, the EPA and EU Commission have specified that a single unit is adequate. For products tested to the TEC specification, this allows for a 10% margin of error so, if the result for the tested device falls within 10% of the Energy Star limit, a second unit must be tested and both units meet the standard. For products tested to the OM specification, the variance is loosened to 15%.
Products will need to be tested and certified for both US markets and European markets separately because of the different voltage/frequencies in the two geographies if the manufacturer wants to sell the product in both regions.
Particularly rigid, the new Energy Star standard (known as Version 1.0) requires that any OM tested product physically built after 1st April 2007 must be recertified because the original Energy Start certification will no longer be valid. For TEC tested products, manufacturers have until 1st April 2009 to recertify products. In the short term, therefore, we may see the Energy Star logo dropped from devices previously certified.
One perceived downside to this certification process would appear to be in the fact that devices need only be tested under mono printing conditions. If this is correct, then we have a serious flaw in the methodology for TEC testing, especially where four-pass laser devices are concerned because the print engine runs at full power for four times as long when printing a single colour page as printing a mono page.
In the event that mono pages are the primary print type, this alters the TEC figure by a huge amount. Although it would also make some difference to the TEC figure for a single-pass laser device, the difference would be relatively minimal.
It should, however, still be accounted for under the compliance scheme.
In summary, the new standard will drive printer manufacturers to continue to develop products that make power savings in every area possible. Most significantly though, we will see more products offering duplex printing as standard or as an option at purchase.
Then it is only a matter of persuading users to activate duplex as a standard component of their printing behaviour!
~End~
