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In a recent interview, the Flemish minister of Media mentioned energy efficiency as one of the advantages of DAB+ digital radio over FM radio. (And thus making the decision by the EU to completely switch over to digital radio in the next few years seem ecologically motivated.)

Asked about the (slowly) growing number of DAB+ users, he is reported to have said:

"Dit bewijst meer dan ooit dat DAB+ de toekomst van radio is: betere kwaliteit, groter gebruiksgemak, een ruimer aanbod, zuiniger qua energie, ..."

which translates as:

"This proves more than ever that DAB+ is the future of radio: higher quality, better user-friendliness, a greater choice [of stations], better energy efficiency, ..."

However, an analog radio set is one of the least energy-hungry appliances you'll find in your house; small portable radios and radio alarm clocks sometimes work for several years on a single set of batteries, and you can even build a radio set that doesn't need batteries at all.
Digital radio sets, on the other hand, necessarily contain a processor and DA convertor; a quick search tells me that the power consumption of the most frugal DAB+ radio sets is around 3.5W at the moment.

Therefore it seems unlikely that this claim is true, at least not when looking solely at the receivers.

Is there a way of measuring the power consumption of radio, e.g. by not only looking at the receivers but also at the power consumption of transmitters, that would make the claim that digital (DAB+) radio is more energy efficient than FM radio true at this point in time?

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    Please quote the claim being made (and ideally translate it to English). It seems like the Minister is making one claim (that the total power used by transmitters is lower), and you are asking us to defend/debunk a different claim (total power used by transmitters & receivers is lower).
    – Oddthinking ♦
    Nov 4, 2019 at 8:22
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    @Oddthinking I added the relevant quote. It doesn't go into any detail, just a vague claim of "improved energy efficiency".
    – user52494
    Nov 4, 2019 at 14:08
  • at least not when looking solely at the receivers - My first thought is that he is referring to the energy required for broadcasting (the antenna).
    – user22865
    Nov 5, 2019 at 12:40

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[Edited to add reference to European Broadcasting Union Cost-Benefit analysis]

A cost-benefit analysis of FM vs DAB undertaken for the European Broadcasting Union based on a detailed analysis of Big-5 EU countries estimated the OpEx requirements for FM and DAB radio transmission (basically power consumption + facilties costs).

DAB had greater energy and facilities costs to achieve the same coverage because with shorter ranges, more stations were required. However digital protocols enable multiplexing of multiple stations on one signal sharing costs between 10 or more stations.

A single chanel would cost c. twice as much on DAB than FM but realisitically one channel would cost on 1/5th of the FM cost when shared.

EDU Tech Review - FM vs DAB Cost-Benefit

While this report focuses on operating costs in general (of which power is one of the main ones) the same conclusions are found in analysis focused narrowly on power consumption.

For example the conclsions match very closely those of the analysis below that is wholly energy focused (though comes from a pro-DAB group so perhaps can't be 100% trusted!). They estimate that the power requirement for transmitters to cover all of Bavaria is c. 116kW of electricity for FM and 224kW of electricity for DAB but the DAB transmitters can multiplex 10 channels for the FM stations 1 making it 116kW vs 22kW per channel.

"Green Broadcast" DAB vs FM (DAB interest group view)

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  • As I starting my comment: "This is from a pro-DAB group so perhaps can't be 100% trusted". The ability to multiplex would logically increase you efficiency while even this group acknowledge the total power requirement for area coverage is higher on DAB, presumably as a result of the small cells. So the argument seems prima facie credible.
    – Duke Bouvier
    Nov 4, 2019 at 13:00
  • I guess this means that the answer will be a complex calculation based on the geography of the country, the number of listeners, the number of stations, the degree to which stations share transmitters, and the chosen trade-off between quality and number of stations. It may be impossible to disprove any claim about it unless you have access to very specific data.
    – user52494
    Nov 4, 2019 at 13:55
  • There are some basic things: - DAB as a digital signal can multiplex; FM cannot. Sharing bandwidth creates massive efficicences. - DAB works in small cells needing more transmitters (and less than pro-rata reduction in power. - Question looked to be power consumption. Whole-lifecycle cost is a different issue, as is power use of consumer devices - which drops continoous, but anyway is worst for multi-mode devices which rather vitiates the question.) The overall message of this piece is directionally correct despite their spin. Of course a better sources woudl be welcome.
    – Duke Bouvier
    Nov 4, 2019 at 17:17
  • @xenophantic - agreed, which fortunately someone was commissioned by the European Broadcasting Union to do :-) (See edited reply above)
    – Duke Bouvier
    Nov 4, 2019 at 18:31
  • @DukeBouvier That EBU study is a great find. It's a bit strange that the multiplexing vs. quality trade-off is only mentioned as "96 kbit/s will be considered the reference bitrate" and they don't even explain whether this corresponds to the 10 or 18 stations per signal scenario. I think they're showing some pro-DAB bias there. You could argue that for a fair comparison they should have used audio quality comparable to FM.
    – user52494
    Nov 4, 2019 at 22:55

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