A white paper independently produced by Meko Ltd and sponsored by Lenovo.
Introduction 2
Avoid 3
Reduce 4
Power 4
Power savings 5
Ambient Light Sensor 7
Allowing for Lifetime 7
Proximity Sensor 8
Reduced Materials 10
Elimination of hazardous material 10
Reduced & Re-usable Packaging 11
Re-Use 12 Re-usable Bag 12 Recycle 13 Recycled plastic 13 Approvals 15 EPEAT Gold 15
TCO Certified Edge 16
Conclusion 17
Introduction
Last year, we published a white paper in which we reported on a new Lenovo monitor that broke new ground in using the latest film
technologies to achieve new standards in power reduction. Lenovo encouraged other companies to go the same way and we have seen a response widely in the market.
However, energy consumption is only one of a very wide range of
environmental concerns in high technology, albeit one of the most urgent and important. This year, the company asked us to evaluate a new
product which pushes much further into other areas as well as continuing to improve energy efficiency.
We chose to use a well established model from the waste management world. This model helps to establish the priority of actions that are environmentally positive.
The hierarchy suggests that the best way to look at any activity that uses energy or material resources is to avoid it if it is unnecessary. The next step is to look at ways of reducing the use of energy or materials. Moving down, can products be re-used? If they can't be re-used, can the materials be re-cycled? If the materials cannot be recycled, can the energy used to create them be recovered in some way?
Products should be disposed of only when none of these actions is possible.
We're going to look at the new L2251x Wide monitor using this concept.
Avoid
Avoiding the use of monitors is not a realistic choice. Especially in
professional environments, users don’t look at their screens for pleasure, but to achieve their working objectives.
Reduce
The concept of reduction can be applied in a number of areas of monitor use.
Power is an obvious way of applying the ‘reduce’ principal, but there are other ways to apply the 'reduce' concept. The amount of materials used to make the product can be reduced, as can the amount of packaging materials used. A reduction can also be made to the hazardous materials used. Lenovo has addressed all of these areas with its new monitor. Power
Computer monitors and office equipment take a lot of power. Monitors are a significant part of that energy consumption1. Reducing power use is important for cost and other environmental reasons.
The way that LCDs work is quite surprising. Unlike other technologies which produce light only where it is needed, LCD monitors use backlights that illuminate the rear of the display surface continuously. The display device (known as the Liquid Crystal cell) effectively has to 'create black' by blocking the transmission of this light. LCD cells are put together with backlights to create LCD modules, which are then fitted into monitors.
1The US Environmental Protection Agency (EPA) estimates that by the end of 2006, its Energy Star
campaign had saved 170 billion kWh of electricity from changes to monitors alone– equivalent to lighting 95 million homes and reducing CO2emissions by 33 million tonnes per year.
http://www.energystar.gov/ia/partners/prod_development/revisions/downloads/monitors/Monitor_Web inar.pdf
Until now, backlights have almost exclusively been cold cathode
fluorescent tubes (CCFLs) as these are a very efficient way to produce light and are very low cost.
Last year, monitor makers, following the lead of Lenovo, adopted new film technology to reduce the number of backlight tubes used in their monitors. This not only reduces the materials, it also reduced the power consumed.
With the L2251x Wide, the light source has been changed from cold cathode fluorescent lamps (CCFLs) to white Light Emitting Diodes (LEDs). (for more background on the technical differences between CCFL and LED backlights, see Appendix 1)
Power savings
The typical power consumption level of the L2251x Wide is 21W. This is a dramatic reduction on the typical power consumption of current
monitors of this class2. The average power consumption of current monitors in this class is 49W3, so if all monitors switched to this technology, there would be a dramatic reduction in power usage. The reduction is equivalent to a 57% power reduction compared to the previous CCFL-based model from Lenovo.
2Just one and a half years ago in its April 2008 white paper, 'Your computer and the Climate', TCO
said that "We already have 22 inch displays that use less than 40 watts in operational mode". This was regarded as remarkable, but now that power has been cut by almost half again.
3Based on the average manufacturer’s quoted power consumption of 372 different 22” wide LCD
monitors in Meko’s database. The most common power consumption was 45W (90 models). Lenovo’s equivalent CCFL model is also rated at 45W, so that metric seems reasonable.
Our product databases show that the average power consumption of all LCD monitors on the market in the last year is around 45W4.
We have looked at the possible implications of the introduction of the LED technology if other makers also take up the concept. We are basing our numbers on the current forecast from DisplaySearch for worldwide monitor sales. We took that data and applied the power levels of the current products in the market to estimate the total power consumed by newly-produced and sold monitors.
We have then made an assumption that in 2009, just 5% of monitors have the new LED-backlit LCD technology, rising to 30% in 2010, 50% in 2011, 70% in 2012 and 100% in 2013. We have also assumed that the power saving reduction would be 53% (the saving from the
equivalent Lenovo monitors).
Annual Saving (billion kW/H)
0 5 10 15 20 25 30 2009 2010 2011 2012 2013 B ill io n K ilo w at t h o u rs sa ve d Saving (billion kW/H)
Overall, this calculation shows a cumulative total potential saving of 48.6 billion kilowatt hours of power by the end of 2013.
This calculation allows us to calculate some equivalents to give a sense of scale to the difference that the change could make. One barrel of oil has the equivalent energy of 1,700kWh5. Oil-fired power generation is
4Based on an analysis of models advertised in Europe in the year from August 2008 to August 2009, a
total of 423 different models.
34% efficient on average around the world.6This means that the output in electricity generation from one barrel of oil is 578kWh. One barrel of oil is 42 U.S. gallons, so we can calculate the equivalent of oil saved. By 2013, the total is 3.5 billion gallons of oil, with a continuing annual saving throughout the lifetime of those monitors.
Another advantage of energy saving is to reduce CO2 emissions. In the US, producing a single kW hour of electricity generates 0.6083 kg of CO2.7Applying this figure to the total of electricity saved gives a total saving of 29,570,943 tonnes of CO2saved by 2013.
Ambient Light Sensor
A new feature8that Lenovo has added to the L2251x Wide is an ambient light sensor. The feature uses the integrated webcam to adjust the
brightness of the image on the screen, which can make the image more comfortable for users.
As we noted in our review last year of two of Lenovo’s monitors:
“in extended use, we found the maximum brightness level of the L194W (rated at 300 cd/m2) to be too bright, although initially the ‘visual punch’
of the display made it look attractive”.
Allowing for Lifetime
It might be considered that a good option to reduce power consumption would be to reduce the maximum brightness of the monitor to a lower level. However, there are two powerful reasons why this would not be a good idea.
First, not all users are able to control the ambient brightness. For example, monitors might be used in retail, transport or other
environments where it might be very difficult to control the ambient
6International comparison of energy efficiency of fossil power generation
W.H.J. Graus, M. Voogt and E. Worrell
Energy and Climate Strategies, Ecofys Netherlands BV, Kanaalweg 16-G, 3526 KL Utrecht, Netherlands
Energy PolicyVolume 35, Issue 7, July 2007, Pages 3936-3951
7http://www.eia.doe.gov/cneaf/electricity/page/co2_report/co2emiss.pdf
8In fact, this feature was included first back in the 1980s in CRT monitors. However, the sensors at
that time tended to react to a different spectrum of light than human vision and so users were not particularly happy with the operation of the sensors. In recent years, new sensors that better match human vision have been developed.
lighting to the level that would be suitable for an office. For those users, the maximum brightness might really be essential. The level of brightness on the Lenovo monitor is 250 cd/m2and that is in line with market
requirements.
The second factor is the lifetime consideration. LEDs, like CCFLs or other light sources, reduce in efficiency over their lifetime. Therefore having a maximum brightness that starts above the general brightness means that the lifetime of the product with acceptable brightness should be longer and that is positive from a resource usage point of view9.
However, there is a balancing point here. Our previous White Paper
showed that 250 cd/m2is long enough to give a good lifetime and, unless lighting conditions are very difficult, producing a monitor with even
higher brightness simply increases the risk of using too much power. Proximity Sensor
The new monitor is fitted with a proximity sensor which, like the ambient light sensor, uses the integrated webcam. This detects when users are away from the monitor and can reduce the power consumption by switching into power-saving modes when there is nobody watching the display.
Tests performed with the proximity sensor found that around 22% of working time was spent away from the PC. Clearly, PCs and their operating systems already have ways of triggering power saving modes by detecting keyboard and mouse activity. When there is no activity, the system goes into power saving mode.
However many users don't like to have these functions enabled as there may be information on the screen that is needed for reference, even if there is no data input going on. They also like to have information available instantly and prefer not to wait even a few seconds for the system to power up.
In those cases, enabling the proximity sensor could provide power savings when the user is away from their desk.
Proximity sensors can also make a big difference if monitors are accidentally left powered on overnight, over weekends or just during
9For a more detailed look at this topic, check our 'The Power for Change' white paper published in
meal breaks. A monitor left powered on from 5.00pm on a Friday evening until 8.00am on a Monday morning will have been powered for 63 hours - much longer than a standard working week.
Taking these factors into account, it seems reasonable to us to assume that a proximity sensor could save 10% of overall power consumption. If we assume an average power consumption of 20W if other monitor makers adopted the low power backlight technology, and a 10% saving over 2500 hours per year, there would be a power saving of 5kW hours per year10.
Annual Saving from Proximity Sensor
0.0 0.5 1.0 1.5 2.0 2.5 2009 2010 2011 2012 2013 B ill io n K ilo w at t h o u rs
If we make the assumption that adoption followed the same pattern as for LED technology, then the saving from the proximity sensor would be 4.31 billion kilowatt/hours by 2013, which means an equivalent of 313 million gallons of oil and a reduction in CO2 of 2,622,329 tonnes.
We regard this as a conservative estimate of the value of the proximity sensor as it would be relatively easy to include this feature in monitors at low cost, so the adoption could be much quicker. We were also unable to find any independent research showing the amount of time that the
sensor operated in different working environments, so we have been conservative.
10Of course, the less power that the monitor consumes in its on state, the smaller are the savings from
additional technologies. This highlights the importance of focussing a lot of attention on the basic efficiency of the LCD/backlight assembly.
Reduced Materials
Compared to its previous monitor models, Lenovo has focused a lot of attention on reducing the materials used in the manufacture of the product and also in the transportation to the end user.
Looking first at the monitor itself, compared to the previous generation of 22" monitor, there has been a reduction in plastics usage of 14% from 1.26kg per monitor to 1.089kg. In addition, the metal content of the new monitor has been reduced from 2.47kg to 2.36k, a reduction of 4%.
Elimination of hazardous material
One immediate advantage of changing to LED backlights is the elimination of mercury11 which is a hazardous material.
The elimination of mercury is a benefit in itself, but also makes recycling of products at the end of life much simpler. Great care has to be taken in disassembling LCDs with CCFLs to ensure that the mercury does not get into the environment. In some parts of the world, insufficient care is taken in dealing with the mercury and this can lead to environmental problems.
The new monitor uses special LCD glass that is arsenic-free12. This type of glass has been developed recently and is an improvement from an environmental perspective at the end of life of the monitor.
Lenovo told us that the L2251x Wide is a 'low halogen' product and that parts used in the monitor are selected on that basis13. Halogens such as bromine and chlorine are used in electronics equipment as flame
retardants and other applications.
Lenovo reported that the L2251x Wide uses less than 900 parts per million of halogens.
11Mercury is used in the fluorescent lamps to improve efficiency. Although mercury is normally not
allowable under regulations such as ROHS in Europe, a special exemption is often given for LCDs because mercury also gets into the environment in power generation. Research by the EPA in the US showed that replacing CRTs with LCDs reduced power consumption enough that the overall amount of mercury getting into the environment was reduced.
12Arsenic was traditionally used to ensure that glass was free of bubbles as a very tiny bubble can
completely ruin a sheet of LCD glass.
13For regions where US power cord, EU power cord and UK power cord are used,as well as Japan,
Denmark, Switzerland, Italy, Australia, New Zealand and South Africa, monitors will ship with 'low halogen' power cords at the time of general availability. For all other regions, monitors will ship with regular RoHS-compliant power cords at time of general availability.
Reduced & Re-usable Packaging
In designing the new monitor, Lenovo has paid a lot of attention to the reduction of materials and the reduction of size of the packaging.
A reduction in material usage is a fundamentally environmentally-positive move and the firm has reduced the weight of packaging from 2.73kg to 2.63kg, a reduction of 4%. The carton is composed of 85% re-cycled material while the cushion material is made of 100% re-cycled low-density polyethylene (LDPE).
4
LDPE
Re-Use
Re-use of complete monitors is unlikely as the technology improves very dramatically between the time of purchase and the end of life. However, careful attention to this concept has allowed Lenovo to find a way to re-use some of the packaging.
Re-usable Bag
LCD monitors are shipped inside cartons but are held within plastic bags. The bag has the important function of keeping the monitor dry and dust free during storage and transit and is not an optional item. However, Lenovo has made 'virtue out of a necessity' by considering this item from an environmental point of view. The bag cannot be avoided, nor reduced further, but it could be re-used.
Lenovo has adopted a new bag design that can be re-used for a variety of purposes in the home or in businesses.
Recycle
The final point to be considered in the reduce, re-use and recycle list is recycling. Much work is going on in the industry to understand the best way to recycle LCDs. At the beginning of life, there are ways to bring the re--cycle principle into action/.
Recycled plastic
85% of the weight of the plastics used in the L2251x Wide comes from recycled plastic material. 65% of the plastic in the monitor comes from post-consumer content - that is to say, plastic that has already been used in a product at least once. Products that the plastic might have come from include home appliances, computers, vehicles and office equipment.
Collection
A further 20% comes from 'post-industry sources' in other words, scrap from plastic or plastic part manufacturing. For example, this plastic might be out of specification products or unavoidable scrap such as trimmings from mouldings.
Collection
Recovery
Processing
Re-use
Shredding
Recycling plastic saves a lot of energy and non-renewable resources and reduces carbon dioxide emissions14.
If all makers adopted recycled plastics for their monitors on the same basis as Lenovo, then big savings in energy and CO2production could be achieved.
If all makers did switch to recycled plastic from 2010, on the assumption that there is 1kg of plastic in each monitor15 and that 85% of the plastic used was recycled material, then the total weight of recycled plastic from 2010 to 2013 would be 616,000 tonnes16.
Using the equivalents, we can calculate that this would mean a
cumulative saving of 2.16 million tonnes of CO2and 422 million gallons of oil by 2013.
14One ton of recycled plastic saves 5,774 Kwh of energy, 16.3 barrels of oil, 98 million Btu's of
energy, and 30 cubic yards of landfill space. Source Stanford University Recycling Center.
15Most monitors sold are smaller in diagonal than the Lenvovo 22"
16Assuming sales of 725 million monitors in 2010 to 2013 at 85% recycled material. The forecast for
Approvals
Of course, there are many organisations around the world that approve or endorse products that are considered to be especially environmentally aware. A full discussion of this topic is beyond the scope of this document, but we have looked at the certifications that the Lenovo product has won that are 'above and beyond' what we would regard as the minimum requirements needed to be in the market and beyond the legal requirements.
EPEAT Gold
EPEAT was established as an aid to procurement and is a not-for profit corporation registered in the US. Products are awarded a level of Bronze, Silver or Gold according to their conformance to specific criteria in IEEE 1680, an international standard "for Environmental Assessment of Electronic Products". Products are self-certified by manufacturers but verification is undertaken by EPEAT on a sample basis.
Purchasers of monitors can use the EPEAT labelling system to ensure that the product purchased meets a particular class of overall
environmental impact, reducing the need to make detailed and difficult decisions between different products.
Meko regards EPEAT Gold as a good indicator that a particular product has been designed and manufactured with close attention to the
TCO Certified Edge
TCO is a Swedish labour union that established a product certification scheme and supporting company in the days of CRT monitors when there were concerns about product safety and visual ergonomics. The
organisation has since extended its certification schemes and interests to include environmental impact and energy usage.
In 2009, TCO introduced a new level of certification 'TCO Certified Edge'. The Lenovo monitor is the first to be awarded the Edge certification.
TCO says that the 'Certified Edge' programme is designed to allow
manufacturers to differentiate their products by meeting optional criteria. At the time of writing, the only optional criteria is for the display to use at least 65% recycled plastics, which the Lenovo product does. TCO clearly supports the moves by Lenovo in this direction as its press release says:
"Through its high percentage of recycled plastic in the ThinkVison L2251xW, Lenovo has shown exceptional leadership by pushing the boundaries of green design, while designing a product that also meets
the high demands of today’s user".
Products that have the 'Certified Edge' label must also meet the criteria of TCO Displays certification which covers a much wider range of performance and environmental impact areas.
Conclusion
The new Lenovo L2251x Wide represents the leading edge of products in the market in terms of its minimised environmental impact. The reduction in power from the use of LED backlights and the use of a proximity
sensor are genuine and significant steps forward in reducing the power usage and use of resources.
The use of recycled plastics is also a significant and useful step in reducing the environmental impact of new monitor purchases The power savings on individual units may not seem huge, but the
monitor market is a very big market (more than 200 million units per year by 2013) and so there is a large 'scaling up' of savings if improved
technologies are widely adopted.
If other monitor makers adopted the same technologies at the rates that we have assumed in this document, the total cumulative savings of oil consumption would be 4.268 billion gallons, with a total reduction in CO2 emissions of 34 million tonnes. Given that an acre of forest can
sequester around 2.6 tonnes of CO2, this is an equivalent of around 13 million acres of forest.
Annual savings from the LED and proximity sensor would be 1.91 billion gallons of oil and 16 million tonnes of CO2.
----Appendix 1 - CCFL vs LED Backlights
LCDs differ from many other kinds of electronic display by being transmissive. The display system consists of a liquid crystal image generating sheet that is illuminated from behind by a bright light,
traditionally from a number of cold cathode fluorescent lamps (CCFLs). In desktop monitors, these lamps are continuously lit and are normally at the edges of the display. The light is reflected into a light guide and from there is transmitted through the polarisers and filters of the LCD.
Input Power 100% Inverter 75% Input Power 100% Inverter 75% 15% 15% Prism Prism Diffuser 60% 60% 80% 80% LCD Cell - 10% 15% 15% Reflector Standardpolariser Standardpolariser CCFL CCFL
Fig 1. Typical efficiencies at each stage of an LCD module17 Like the CRTs that dominated the personal computer screen world from the 1980s until recently, LCDs are fundamentally very inefficient devices. Of the light that is emitted from the backlight of an LCD, as little as 5% -10% will actually be emitted from the front of the display as visible light, with the rest being emitted as heat. Improving the efficiency of the light transmission of an LCD using improved technology could either boost brightness, or reduce energy consumption if the brightness level is held constant.
In the table below, we’ve shown the effect of each stage on the efficiency of a typical LCD.
Power Input Efficiency Power Output
Inverter 100.00 75% 75.00
Lamp/reflector 75.00 15% 11.25
Optical coupling of lamp to light guide 11.25 60% 6.75 Output of light guide 6.75 80% 5.40 Cell (inc polarisers & filters) 5.40 10% 0.54
Table 1. Typical efficiencies at each stage of an LCD module
LEDs have basic efficiency that can be better or worse than CCFLs. However, the light from the CCFL has to be reflected back into the backlight and that process is not as efficient.
LEDs can be better coupled to the backlight, so that more of the light coming from the LED ends up in the light guide at the back of the LCD.
Fig. 2 More of the light from an LED gets into the wave guide (source Kennedy, Toyoda Gosei, DisplaySearch USFPD Conference 2008)
The power supplies/driver chips can also avoid the high voltages of inverters and can typically have around 90% efficiency.
Prism Sheet
Diffuser film
Reflector
Standard polariser
Standard polariser
LEDFig 2. LEDs couple better to the light guide.
Power Input Efficiency Power Output
Driver 100.00 90% 90.00 Lamp/reflector 90.00 15% 13.50 Optical coupling of lamp to light guide 13.50 90% 12.15 Output of light guide 12.15 80% 9.72 Cell (inc reflective polariser & filters) 9.72 10% 0.97
As can be seen, the amount of light coming out of the LCD is significantly improved, by the better coupling.
LED makers are also a semiconductor technology and performance is increasing rapidly, broadly in accordance with Haitz law that 'every decade, the cost per lumen (unit of useful light emitted) falls by a factor of 10, the amount of light generated per LED package increases by a factor of 20, for a given wavelength (colour) of light'.
In contrast. CCFL technology is very well established and is not improving rapidly.
