Aris Silzars Display Technology Consulting


The Display Continuum

Are We Forgetting Something?…

We have entered the era when “green is in”. The elimination of toxic materials and the savings of energy have become important consumer issues. For us in the display community this trend started rather quietly some years ago with the push to eliminate Lead-based solder in circuit boards. Then someone noticed that CRT glass has Lead in it as well. So even though the Lead is chemically bound up well enough to be used in wine glasses and decanters, with no harm to users, the implication was that somehow this heavy metal could leach out and get into the environment -- and that this too was a “bad thing”. Then we were told that we should eliminate materials such as Cadmium, and more recently Mercury. In all of this earlier modest activity there did not seem to be any great urgency and consumers were certainly not making buying decisions based on which materials – or not – were used in televisions, display monitors, or other display-based products.

But now, with the interest in environmentally friendly products growing, we are seeing a few unusual behaviors along with the good results that are beginning to come our way. Perhaps the silliest overreaction I have encountered was recently reported in the Seattle newspaper. A lady telephoned the Hazardous Materials clean-up hotline because she had broken one of her new “squiggly” fluorescent light bulbs and was worried about all the Mercury she had spilled. And guess what, these folks dutifully responded to her call and after inspecting the premises told her that it would cost at least $30K to clean up her home to make it “safe” again. Of course, once this made the paper, more rational minds were somehow located and the problem was resolved by the common sense method known as “sweep up the broken pieces and open your window for a few hours”.

In spite of these occasional bizarre events, recently we are beginning to see changes that may soon lead to buying decisions being influenced by how “green” we can make a display product.

This new direction in product development became quite evident at the recent SID Display Week in Los Angeles. A number of major display manufacturers were showing flat panel televisions featuring reduced power consumption. The reduced power was prominently featured with large numerical displays next to “before” and “after” comparisons. Clearly this was intended as a product feature soon to be promoted along with display quality, styling, and price.

Seeing these more efficient displays reminded me of all the articles I have recently read about how conventional tungsten light bulbs will be gone in a few years replaced by the “squiggly” fluorescent ones that cause people to worry about how to dispose of them safely. There even seems to be a push in some parts of the world to introduce new laws that will make it illegal to sell or buy tungsten filament “energy inefficient” light sources.

This of course got me thinking – are we really getting the benefits that are being touted? If a fluorescent bulb gives off the same amount of light as a 60-watt tungsten bulb but only uses 13 watts, do we really get a 47-watt saving? And likewise is this also true for a more efficient flat panel television? Where does the extra power lost in a tungsten lamp go? How much do I really save if the fluorescent light source costs several times more than the tungsten light bulb?

It should be no great surprise to any of us that the power consumed by a 60-watt tungsten light bulb shows up as either light or heat. The emission spectrum is simply that of a black body radiator that has a temperature of roughly 2300 degrees Kelvin. So a light bulb will give us a relatively small percentage of its energy as light and all the rest will be radiated as heat into our environment. But is that necessarily environmentally bad? Are we paying a 47-watt penalty for the use of a tungsten light source as compared to the “squiggly” one? As it turns out -- that depends on where you live and how warm you like to be.

Here in Seattle for 10 months of the year the average daytime high temperature is at or below 70º F. In cities such as New York, Denver, Boston, and San Francisco the average daytime high is at or below 70º F for 8 months of each year. Even in places such as Los Angeles and Kansas City the average daytime high doesn't exceed 70º F for 7 months of the year. It’s only in places like Atlanta (5 months) and Austin (3 months), and of course cities in Florida and Hawaii where the daytime highs are consistently above 70º F. But this is the daytime high temperature that in most locations typically occurs for only a few hours each day – it’s not the average temperature.

Therefore, it seems to me that in many locations -- not just in the US but worldwide – most of the energy from a conventional tungsten bulb is not wasted at all. It’s used to supplement whatever other energy source is used to heat the home. And even in the summer months when the temperatures are higher, the days are also longer and there is less need for artificial light. The worst case of course is in climates where air conditioning is used on a regular basis. Then the extra heat energy produced by the 60-watt bulb is not only wasted but there is a double penalty because even more energy has to be consumed by the air conditioner to remove this extra heat.

There is certainly nothing wrong with improving the efficiency of all of our products – from light bulbs to televisions, and especially to battery powered portable devices. However, it’s inaccurate to promote this saving’s as an absolute value based simply on the relative power consumed by these devices. For me, replacing all of the tungsten light bulbs in our home will produce a net energy saving’s for a total of about one week out of each year. That is about how many days each year we run the air conditioner during the evening hours when the light bulbs are likely to be on. And even here in Seattle, we are in the minority since most homes simply use the open window approach on warm days – nature’s air conditioning. For most eastern US locations, air conditioning is considered a necessity so there will be some net loss of energy for at least a few summer months. However, here too the savings will not be nearly as significant as what is typically being promoted. As is often the case, a single numerical comparison can be misleading.

The lower energy consumption being achieved by the improved flat panel televisions is admirable and it’s certainly not a bad direction for manufacturers to take. Nevertheless, there is value in recognizing that the net benefits are not going to be nearly as dramatic as an over-simplified calculation may conclude.

I agree that it’s “good to be green”, but it’s also good to be aware of the real consequences of our actions. Sometimes our enthusiasm can get the best of us.

Should you wish to comment on this topic or others, you can reach me by e-mail at or by telephone at 425-898-9117.