Apr 21, 2020

The truth about the power consumption of LED walls

Themed Entertainment 4 lectura mínima

Power consumption is a decisive parameter when comparing LED displays. If you are researching into your options for an LED wall you might have wondered why the power consumption values for certain LED products are higher than others. The answer is simple: the values are based on different calculations. And you shouldn’t compare apples and oranges. So allow us to demystify the seemingly inexplicable differences in the LED power consumption specifications.

First things first, why should you care about the power consumption of your LED wall?

Energy efficiency closely relates to the total cost of ownership of your product (TCO). Restricted power consumption levels mean electricity expenses are kept to a minimum. In addition, it goes without saying that power consumption is crucial when it comes to sustainability objectives. Energy efficient products also reduce your eco-footprint and are generally better for the environment.

So yes, you should definitely look at the power consumption information when deciding on a new LED video wall, but be aware that in order to make a thought-through decision you need transparent spec information.

Different power consumption indicators explained?

The only power consumptions that can be measured are the maximum, the black level and the standby power consumption.

Maximum power consumption

LED recreates the visual content sent from the input source by lighting up the individual pixels or diodes to different intensities and colors. To show a full black screen, for instance, all diodes are switched off; whilst to present a full white screen, all diodes are powered to their maximum.

The maximum power consumption is defined by recreating a situation where the LED wall is going full power, the product is set to full brightness showing full white content for a certain amount of time. The power consumption measured in this way is the maximum power consumption spec of your product, of course taking into account a small additional margin for environmental variables.

Black level power consumption

Black level power consumption refers to the power needed to run the electronics without showing content on the LED wall. Because even though the diodes are off, the drivers and receiver cards are still consuming energy.

Standby power consumption

When the LED wall is set in standby those same electronics are still working albeit in power saving mode. So, the standby power consumption is below the black level power consumption, but obviously still higher than when the display is completely turned off.

Now, content usually isn’t just full black or white, but shows a variety of colors depending on the application where LED wall is used for. That’s why Barco always refers to “the typical power consumption”.

How to calculate the typical power consumption of an LED wall?

The traditional industry rules of thumb (dividing the maximum power consumption by three) usually don’t take into account the average use and black level power consumptions. For outdoor products with low pixel density and only a couple of drivers, this was on average a correct calculation. But with today’s high-resolution indoor LED products, the black level power consumption has become an important parameter which shouldn’t be left unnoticed. Pixel-pitches are significantly lower, think of the XT0.9 tile, and the pixel density on LED tiles is increasing. More pixels naturally need more drivers to manage the wall. The power consumed by these drivers and extra electronics is not neglectable. Hence, it’s only logical to include it in your calculations. The result will be much closer to reality!

Barco’s calculation of the typical power consumption is based on the black level power consumption, the maximum power consumption and an average usage of the LED wall. On average a customer configures the display at 70% of its maximum brightness, and the typical content on the wall consumes only 33% of that power.

Barco’s calculation of the typical power consumption =

[(Max power– black level power)*70%*33%]+ black level power 

 

 

Traditional rule of thumb in the industry  Barco’s methodology 
  • Max power consumption = 100W
  • Black level power consumption = 30W

 Not taking into account the black level power consumption or average use.

Following this outdated method, the typical power consumption for this LED wall is 100W/3 = 33W

  • Max power consumption = 100W
  • Black level power consumption = 30W

→ The range from full white, or full brightness, (100W) to full black (30W) = 70W

  • Average usage:

 Display configuration at 70% of maximum brightness

→ At full white, the screen typically uses (70W*70%)+30W = 79W

 Content typically consumes 33% of that power

When using this methodology, the power consumption for this LED wall amounts to: 70W*70%*33%)+30W = 46.2W

 

In this calculation we assume that the content consumes only 33% of the configured power, but as we indicated earlier it all depends on the application area and the typical content shown on the display. Suppose you install an LED wall in a lobby to welcome your business visitors by showing your logo and the visit’s schedule on a white background. Since the white requires more power, the average power consumption of this content will be higher than 33%, and the total typical power consumption for this specific case will also result in a higher number. If you install the same LED wall in a control room where predominantly black SCADA1 content is shown, the average power consumption will be lower than 33% and the typical power consumption significantly smaller than in the lobby.

Key takeaways

  • As pixel pitches are becoming increasingly smaller, the effect of the black level power consumption should not be ignored.
  • Yes, one and the same LED wall can have different typical power consumption levels in different environments! Each application has its own typical visualized content which has a huge impact on the typical power consumption.
  • Look at your LED spec sheets with a critical mind. Don’t just go for the theoretical value that looks best at first sight but go for the value that’s closest to your actual truth.

 

1: Supervisory Control and Data Acquisition

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