Low Carbon Computing

Do we need to worry about the carbon emissions from all these extra online conferencing we are doing these days? What is the best way to reduce our emissions from use of ICT? The energy group discussed these issues this week. Gareth did most of the research - he works with computers in his job and knows an awful lot about it. Also, Gareth and Nicola both did some tests on home equipment to see how much power was being used. Here are some of the things we learned. You can see the slides here.

Computers are more and more commonplace.

How many computers do you have in the room with your right now? Perhaps you are in your living room. Obviously there is one that you are reading this article on and at least one in the TV, and another in the remote for the TV. Do you have Alexa or a similar device? Do you have remote controlled LED lights? Perhaps you have a security camera on the front door? Do you have a digital watch? Perhaps you have a smart watch that monitors your heartbeat or how far you have walked today? All of these rely on computers of one kind or another. We have them, we use them, and increasingly we rely on them.

Carbon emissions come from making them, then from having them switched on, and then doing actual work.

It is often hard to get information on lifecycle carbon emissions for products. However, Nicola has a newish Mac Mini (bought last year) and Apple publish the lifecycle carbon emissions for their products so we have a clue about that one. Applying a 40% uplift factor to Apple's figures (as recommended by Mike Berners Lee in How Bad are Bananas), and assuming a lifetime of 3 years, the emissions from manufacture and delivery come to 130 g/day. It uses about 14 W when not doing very much, and up to 40 W when working really hard. So in a typical 8 hour day it might use 0.14 kWh - another 18g carbon. The manufacturing emissions far outweigh those from use, and this is not unusual.

The Mac Mini is quite good at saving energy when idle;  Gareth's WiFi router is not. It takes about 13 watts all the time, and when it is working hard, for example downloading video, it uses only a little more, increasing to about 15 watts. Generally speaking, older equipment is less good at saving energy, especially desktop computers, while newish equipment is better, especially if it works off battery such as laptops, tablets and phones.

Manufacturing emissions mean it is often better to use a less efficient old machine than buy a new one.

This chart compares carbon emissions per day from Nicola's new Mac Mini and a monitor of similar age, with an older monitor and desktop PC of Gareth's. Manufacturing emissions for the older equipment are likely even more than the new kit, but they are not relevant as they are history now. The older PC uses far more power than the new Mac - so much so that the daily emissions for the two computers are the same. For the monitors though, the new (admittedly larger) monitor has three times the emissions of the older machine even though, again, it is much more energy efficient in use. So you will not save carbon by buying new equipment!

It is also interesting to compare these with a paperback book, if you only read it once and take 7 days. If you read it several times (or lend it to someone else) then this reduces the emissions per day.

Comparing carbon emissions per day: new 27" monitor (5 year life) compared to an old 24" monitor, new Mac Mini (3 year life) v. older desktop PC, based on 8 hours use/day. Also reading a paperback book over 7 days. Data from Apple, Dell, measured power consumptions and, for the book, from How Bad are Bananas.

How much extra emissions from a zoom meeting?

So how much extra emissions are we generating from all those zoom meetings? This is actually quite hard to say. The infrastructure is sized for peak demand, so the more we use, the more cables and routers, - and for mobile networks towers and base stations - we need. Then, as with your WiFi router, most of this equipment is on all the time, even in periods of low demand - though this is less true for 5G which has been designed for autoscaling. So if you do not actually attend the zoom meeting, the equipment that allows you to do so is still running and you have not actually saved very much at all, outside the home.

It is the same as with buses. There are carbon emissions from making the bus and more from driving it around the scheduled route, regardless of whether there is anyone on it. One extra passenger makes very little difference.

On the other hand, if lots of people used a reduced amount of network capacity, some network infrastructure could be switched off; this would be like running fewer buses on the same route. If there are not enough passengers to run a bus every 10 minutes, you can run it every 30 minutes instead.

Efficiency improvements have kept energy use steady despite growth in demand.

Demand for internet data is growing rapidly. Over five years, data centre workload tripled and global data volumes increased by more than five times. The energy used to run this network, including data centres, remained stable because they have been getting more and more efficient. However there are limits to this efficiency, and there is still the emissions from building the new infrastructure to consider.

Mobile networks are less efficient and high definition video needs more data.

Most estimates of internet energy use consider all energy use and divide by total data transferred. Mobile networks are far less efficient in these terms, using at least four times the energy for the same amount of data. Resolution also matters - so downloading a film to your TV in high definition can use four times the power of watching a standard video on YouTube. Even so, your TV will itself use more power than the data centres and internet supplying data to it - 23W to download from NetFlix according to one estimate compared to 100W for a large TV and speakers.

What might you be doing instead?

Inside the home, you have to consider the counterfactual - if you were not on that zoom call, what would you be doing? Would you be streaming a film to your TV (bigger screen, high definition video). Or would you be playing a computer game (using even more than the TV) - or reading a book or gardening or going for a walk? The last two might be zero emissions. The book is not - though if you use an e-reader there are few emissions associated with the act of reading.

Do you really need that new computer?

The best way to reduce emissions in homes is usually to keep using your old devices for longer before buying new ones. Unfortunately, there are barriers to this. Apart from actual hardware failures (which may or may not be fixable) there are other reasons why we find we find we have to upgrade. Here are some of them.

• Security updates - most commercial operating systems get regular updates to fix bugs that can let in malicious software. However, these updates do not go on for ever, at which point we need to upgrade.
• Web pages have got bigger and need faster machines - the average size of a webpage has quadrupled in about 6 years (see chart). As well as data and video, web pages often run programs inside them, which also require computer power. This means a machine that was perfectly adequate even 5 years ago can struggle now. 
• We want to run power-hungry games - there are more and more fun (some would say addictive) games with extraordinarily realistic graphics and interaction. A games console can use up to 200W - much more than a TV.
• We need to communicate with our friends and family - and that means video conferencing. We don't want to be left out. Older machines may not have in-built cameras or microphones (but they can be added on with cheap USB devices) and can struggle to encode video without the special hardware built into new machines. However most PC’s built within the last 10 years are capable enough for this task.

Web pages have quadrupled in size over 6 years, requiring more energy to load and display. If you are a website designer, can you simplify your pages? 

What can we do to reduce our emissions then?

There are strategies we can use to reduce emissions but there are costs and benefits. For example:

• Open source software is often maintained longer than proprietary systems. You could try using Linux Mint or Ubuntu instead of Microsoft Windows, though you will have to install it yourself. Also you may find specialist software is unavailable, although there is software to satisfy most people's word processing, email and web browsing needs and many apps can run in a browser rather than having to download an app.
• Do you (or your children) really need to play 'Assassins Creed Odyssey''? Maybe your friends do and you don't want to feel left out. 
• Older machines can often be upgraded with more memory and disk space. Also replacing your ‘hard disk drive’ for a ‘solid state drive’ can provide considerable performance benefits where the hard disk is being used (for example when booting and loading applications) and most older machines can be upgraded in this way. However, you will be stuck with the same processor so if it is processor speed that is the limitation this will not help.
• Can you share your devices with other members of your family? This might enable you to get by with fewer devices, and the ones you do have will get more use before they go out of date.
• Do you need the latest hardware or can you use a secondhand or refurbished machine from someone who really does need to upgrade?

This is just a summary of some of the points raised in the meeting. For more detail, do take a look at the slides.