How you use your computer impacts your energy bill

minute read

After the record-breaking summer we just had, we got curious and started digging into the numbers on emissions from the IT industry. You can read that article here.

Turns out, all this also has a very topical energy cost angle. With energy bills rising everywhere, we thought we would run a little experiment on how much electricity an average laptop uses during an average workday. Mind you, the laptop we used is average for the software engineering industry - it has a separate, discrete GPU and runs several large applications. 

Computer generated emissions and energy consumption

First things first. Much of the emissions from computers comes from their production. In fact, one estimate claims that about 75-85% of their total carbon footprint is generated before the computer is even shipped out (1) - this includes mining for the materials used in its construction and the energy used during manufacturing. 

But beyond production and shipping, what is the energy consumption of a typical computer, and how can individuals lower this? This is a case of ‘little things that matter’, as explained on the Microsoft Sustainable Software blog: 

"The biggest contributor to embodied carbon comes from the integrated circuits within the system especially as our devices get smaller and more powerful. These include components such as CPUs, graphics processing units or GPUs, solid-state drives or SSDs, memory, network processors, wireless processors, voltage regulators, and many more." (2)

This means that small changes to the way your computer runs those components could result in greater efficiencies and lower energy consumption. One of our UK team members, Henry, graciously offered to run a little experiment with his own set-up. 

The experiment

Over the course of one morning, Henry measured how much power his fairly standard 2019 MacBook Pro (2.3 GHz 8-core Intel i9 CPU with an AMD Radeon Pro 5500M GPU) was drawing from the wall using a simple plug-in energy cost metre. Below his data:

To visualise the spikes in power consumption, here is a little line graph - we included the monitor at the far right of the graph (‘steady’ on the X-axis) for comparison:

What can we learn from this little experiment? For one, using processing-intensive apps like, in Henry’s case, IntelliJ or meeting software like Teams, unsurprisingly, leads to an increase in energy consumption. Henry recorded a hefty 50% increase on his MacBook. A more surprising finding is that the use of an external display impacts a MacBook’s ability to use its integrated - and more energy efficient - GPU. Henry’s customised settings usually direct the OS to use the integrated GPU, but linking to a monitor automatically switches this over to the discrete GPU. If you do not use an external display you can use a tool like gfxCardStatus to force your laptop to always use the integrated GPU to save power - however small that is.  

Despite the fact that all computers use integrated circuits, studies have shown that desktop computers use more energy and cause higher emissions when in use than laptops, in fact up to around 175 kg of CO2 a year (3). Compare that to a laptop’s emissions, which, depending on use, lie between 40-90 kg of CO2 in a year. As Henry’s small scale experiment shows, many variables impact on power consumption - from hardware used to processes run, and hours spent actively working on the computer as well as whether or not a user turns the device off when not in use. Hardware also includes external devices like additional screens, modems, printers, cameras and microphones (4), all of which come with their own CO2 footprint, much of it, again, generated pre-sale. 

How to save energy when using your computer

If you want to cut down on your computer’s power usage, a good place to start would be to: 

  • Use only laptops
  • Avoid external displays when possible - they draw power directly from the mains but also laptops use more power once connected to them
  • Optimise your GPU settings - integrated GPUs will use less power than discrete GPUs
  • Turn off your devices when not in use - properly turn off, and also pull out plugs from wall sockets
  • Do not leave your phone or computer charging longer than needed - it both degrades the battery and draws unnecessary power
  • Repair instead of replace your devices 

Endnotes and References

We sourced our information from various online publications and websites, which you can see listed below. But one particular source stood out as being a treasure trove of data, and that is Make Berners-Lee’s book ‘How Bad Are Bananas - the carbon footprint of everything’. We highly recommend you get yourself a copy (used, ideally! And maybe not via Amazon…).

(1) Circular Computing (2021) “What is the carbon footprint of a laptop?”,, 9 August 2021; Available at: [Accessed 20 July 2022] 

(2) Manne, S. (2020) “Examining the carbon footprint of devices”, Microsoft Sustainable Software blog, 23 November 2020; Available at [Accessed at 21 July 2022]

(3) Energuide, “How much power does a computer use? And how much CO2 does that represent?”;; Available at: [Accessed 20 July 2022]

(4) Zetterlund T. (2022) “Do you know how much CO2 your computer use?” (sic), Torbjorn Zetterlund, 4 January 2022; Available at: [Accessed 20 July 2022]

Have a project in mind? Let's talk.

Contact us