Love to know where this number comes from

According to HCVA, a classic car generates 563kg of C02 a year, which equates to 20pc of the emissions from powering a computer for a year.

2.5 tonnes of CO2 for one computer for one year? Actually, closer to 3 tonnes. The UK average emissions per capita are only just over 5 tonnes I think that’s without counting imported and embedded emissions.

A complete desktop uses an average of 200 Watt hours (Wh). This is the sum of the average consumption per hour of the computer itself (171 W), the internet modem (10 W), the printer (5 W) and the loudspeakers (20 W). Assuming that a computer is on for eight hours a day, the annual consumption comes to 600 kWh. That corresponds to CO2 emissions of about 175 kg per year, i.e. 1.75 % of the average annual emission of a Belgian.

A laptop uses considerably less: between 50 and 100 Wh that it is on, depending on the model. If it is used for eight hours a day, consumption therefore varies between 150 and 300 kWh/year. That corresponds to CO2 emissions of between 44 and 88 kg per year (or between 0.44 and 0.88 % of the average annual emission of a Belgian).

Someone, somewhere, is spouting bollocks, aren’t they?

26 thoughts on “Love to know where this number comes from”

  1. Rational Anarchist

    Assume a 1kW desktop (instead of 171W) and 24 hours per day and you get close to what the first one is claiming. Of course you’d struggle to find a 1 kW computer in general use nowadays…

  2. The Meissen Bison

    a classic car generates 563kg of C02 a year

    It’s always a surprise that it doesn’t occur to the people who do this kind of “study” that they end up with a spuriously precise number.

    Most classic cars spend most of the year under dustsheets in the garage and the amount of CO₂ they “generate” will probably be a function of whether or not there’s a trickle-charger connected to the batteries.

    Please can the average annual emission of a Belgian join the length of a London bus and an area the size of Wales in the pantheon of useful rules of thumb?

  3. I once calculated the numbers and if I recall, using a laptop all day was about the same as driving a modern car for a mile.

    Rough rule of thumb: it just isn’t worth worrying about household electronics, especially if using them saves you from driving somewhere.

  4. I think someone has read the power labels on each device and assumed because they are rated up to X that is how much they use. The equivalent of assuming the classic car will be constantly running at its highest revs and top speed, rather than spending most of its time idling.

    Note they claim ( that on average the classic car only does 1200 miles a year so not comparing levels of usage, and presumably they have used the worst possible electricity (dirty coal?) rather than taking into account that much of the electricity will be green or nuclear.

  5. From their page “The average number of times historic/classic vehicles are taken for a drive annually is 16.”

    So by their own numbers each trip emits 35Kg. If the car was actually used for 250 working days that would be 8750Kg in a year

  6. Abacab, pendant alert – this is a common misconception regarding loud speakers. The loudness is more dependent on the ‘sensitivity’ of the speakers, measured in Decibels dB, than the ‘wattage’. A 50 watt amp will not sound twice as loud as 25 watt amp (logarithms and all that).
    But a speaker with an efficiency of 93dB will sound twice as loud as a speaker with an efficiency of 90dB for the same input level. It’s how valve amps with miniscule outputs (some single ended triodes output 3 watts)can fill a room with sound when partnered with horn loudspeakers with an efficiency of 100dB +.


  7. Forgot to mention re: wattage: A 50 watt speaker will not be twice as loud as a 25 watt one of the same efficiency…..

  8. With computers, they’re reading the label on the back. What they actually use depends on what you’re doing. Some heavy processing like video editing you might get up near the rating for periods. That’s when you start thinking about fitting processor coolers. Web browsing you’re hardly using anything unless there’s a lot of video on the pages.2-3 % of processor capability. After all, you do the same thing on a phone that’ll run for a couple of days on a battery.

  9. Bloke in North Dorset

    Anyone using 20W speakers at 20W all day must be very, very hard of hearing…

    Its a long time since I did amplifier and speaker design theory but I can see that much will have change. The main reason you have 20W speakers is so that you can run them at 10W and and the response curve of the speakers and amps with be linear. When you ramp up to full power you get distortions.

  10. This also conflates emissions from petrol (known and fixed) with emissions from electricity (variable by source and could be zero). It is therefore completely inappropriate to compare these unless one states for example “electricity from a coal power station”, which is increasingly unlikely. And as already noted, the rest appears to be poppycock too.

  11. When my laptop PSU blew up I used a bench power supply as a stop gap until a replacement arrived. Watching the digital ammeter was quite informative – apart from short periods during boot up and loading various programmes, very little power is used during normal web browsing & emailing (which I imagine is what most folks are doing). This also tallies with what Task Manager shows, in terms of CPU load. Even watching videos isn’t that bad, and short of doing demanding jobs like video processing, it’s actually hard to get near the maximum current draw for more than seconds. With a variable speed cooling fan you have another indication of how hard it is (or isn’t) working.

    And “Don’t forget that none of this matters anyway because CO2 isn’t a pollutant” is entirely correct…

  12. Hmm.. yeah… Given that a car is in itself its own environment..

    Did they figure in the running cost in CO2 of keeping the room the PC/laptop is in at something resembling comfortable for humans? Thought not..

    Apples, Oranges…

  13. Also, during the half of the year when you are running the central heating to maintain a given temperature by thermostat, every joule of heat from your computer will compensated by one less joule from your heating system.

    Does anyone else think ’emissions of a Belgian’ was a reference to that statue in Brussels?

  14. Whoever came up with the numbers is frankly a moron – from the article I can see, they don’t want to volunteer their identity…

    Why is it that so much associated with “climate catastrophe” is exaggerated in such a fashion, always “worse than was first thought” – the perpetrators should be sought out and covered with old engine oil and covered with the contents of an old down duvet.

  15. Modem?!?! How many people are still using modems? (Although I grant that a router will use a similar amount of leccy.)

  16. Mr Womby: The modem (there is still one) is buried inside the wifi router for most people. However the modem design is rather different to those in the old days of dial-up, as the technology is totally different to get some tens of megabits per sec up and down a phone line.

  17. Given that “climate change” is the biggest pile of shite con since……well ever, who cares how much CARBON DIOXIDE (can’t these ubermorons at least pay some lip service to me what they are hysterical about) a car emits.

    I don’t. Never have and never will.

  18. Steve in Canuckistan

    It’s not the power supply watt rating that is important for CO2 emissions but the VA. Some home electronics devices have incredibly poor efficiency, low single digits for some mains powered smoke detectors for example(not sure if rules have changed in UK etc. Been out of that business for a while now). Sure you aren’t paying for it directly but the generator is, so you will be paying in the end.
    Of course this doesn’t mean this study isn’t bollocks.

  19. Gah.

    The first clue to the accuracy of the article is that in the same paragraph they mix watts and watt-hours. Result is word salad – you can’t check it because it doesn’t make sense.

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