There is a claim that adverts sometimes include animations, which requires more energy to display, and that, hence, ad blockers save significant energy?

Source: Blocking Online Ads May Save Energy

Using Firefox 3.04, with AdBlock Plus and NoScript, a browser add-on that blocks client-side scripts, Hansen realized a power savings of 11 watts, based on average readings taken at the ten Web sites that, thanks to their use of rich media, draw the most power.

These power-hungry sites, according to Hansen's numbers, include: 1.) myspace.com, 2.) gamespot.com, 3.) go.com, 4.) espn.go.com, 5.) bestbuy.com, 6.) disney.go.com, 7.) weather.com, 8.) gamefaqs.com, 9.) tribalfusion.com, and 10.) amazon.com.

Is this true?

  • 1
    Actually there are notable claims (and studies) that it's true in case of mobile apps on 3G (directly related to this: skeptics.stackexchange.com/questions/15672/…)
    – vartec
    Apr 22, 2013 at 10:12
  • Note that the linked article was written in 2008, so the difference in power use on a modern computer may be less noticeable - an entire iPad uses less than 11W of power on average
    – Johnny
    Apr 24, 2013 at 18:03
  • Semi-related: reminded me of blackle.com which claims ( blackle.com/about ; equally dubiously) massive power worldwide would be saved by a black google home page (depends enormously on display tech of course!)
    – timday
    Apr 26, 2013 at 20:11

2 Answers 2


Significant may be in the eye of the beholder.

On modern CPUs (and motherboards), power draw varies based on load. Successfully preventing ads that require CPU cycles to display (compared to a page of text with no ads) would vary the CPU load (and presumably other motherboard loads as well).

This article gives an idea of power requirements comparing idle and busy CPUs:


And in my hasty testing, on espn.go.com, my Intel Core i5 tower draws 63 watts while the 'ad' is 'playing' and settles to 56 watts when the 'ad' finishes. (It initially draws up to 70 watts while refreshing the contents of the page, then clearly settles at 63 watts while the ad plays) If ads are constantly refreshing and displaying motion and sound, that is most certainly creating CPU load.

Measured with: http://www.p3international.com/products/p4460.html


While it is true that everything has a price (and CPU calculations cost electricity, with none being available for no additional energy cost), the issue is one of scale and whether or not the results are *material - that is to say, if it is significant enough to warrant anyone to choose to use or not use ad blockers based upon it.

Looking at the claim itself, the informal study itself is here: Browser Power Consumption Quite frankly, it seems perfectly reasonable as Flash especially can really draw lots of CPU cycles (and thus power) due to the nature of how such animations work (often using vectors, numerous floating point calculations of multiple complex objects, layers, view-port culling which is not always optimal, video card tie-ins to assist in some of the processing...).

Note that every system is different, and the more energy hungry the device the more this is an issue.

But if we take the case of 11 watts, as an individual this is extremely small even if you browse 24 hours a day, all month long - then it would add up to maybe half a kilowatt hour. Given how people actually use their devices, it's probably more like 0.1 or 0.05/kwh. Here's some source information on calculating cost of energy and kwh: Cost of Electricity

However, on the other hand, this is something that an individual needs to only do maybe once a year or even less (thanks to auto-update software), and it does not even bother to even try to calculate savings in network bandwidth, or in the time savings of faster page loads and less time wasted on ads that are only rarely of any value to the individual.

Now, on the aggregate this is a bit more compelling, and could be considered a material factor to consider for IT departments on large campuses, government agencies, software vendors (like Mozilla including the plugin by default...), etc. On a campus of 10,000 people with thousands of workstations, a 0.05/kwh/user/month savings could shave 500/kwh off an electric bill, save lots of download bandwidth, etc.

Back on the other hand, note that is all only considering a desktop PC, which is the most power hungry internet-consuming device in existence today. The iPad 2, by comparison, has a battery rated at a maximum capacity of 25-watt-hours source, and makes an end run on all this by simply not supporting Flash in the first place - though it still supports AJAX and other types of animations, of course, so is still somewhat served by ad blockers.

The authors themselves say there are far more potent ways of saving energy, but it seems to validly be another small - but measurable and real - benefit of ad blockers.

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