I’ve spent the last month trying to reduce the carbon footprint of the websites I have (some) control over. When talking about this with other people they often look at me blankly before asking “aren’t you taking this a little too far?”.
The simple answer is no. In fact, it is probably the most effective use of my time when it comes to reducing carbon dioxide emissions.
Carbon emissions from distributed code
All of my WordPress plugins combined run on well over 2 million different websites, each website receiving who knows how many visitors.
At an assumed average energy expenditure of 2,9 kWh per GB 1 this means that every kB saved equals an energy reduction of about
2,9 kWh / 1.000.000 kB * 2.000.000 websites = 5,8 kWh if each of these websites received exactly 1 visitor.
Let’s assume the average website receives about 10.000 unique visitors per month and serves files from cache for returning visitors. The total amount of energy saved by shaving off a single kilobyte is then
5,8 kWh * 10.000 visitors = 58.000 kWh.
58.000 kWh of energy produced by the current European electricity grid equals about
58.000 * 0,295 = 17.110 kg of CO2.
Shaving off a single kilobyte in a WordPress plugin running on 2 million websites reduces CO2 emissions by 17.110 kg per month!
To put this into perspective, that is the same amount of CO2 saved per month as:
- Driving my Toyota Yaris for 114.000 kilometers. (158 g CO2 per km)
- 25 flights from Amsterdam to New York. (679 kg CO2 per flight)
- Eating 684 kg of beef (25 kg CO2 per kg of beef)
Ignoring the absurdity of those numbers, I already work from home, am a vegetarian and didn’t take any flights in the last 3 years so it seems I am stuck trying to make the web more efficient.
What can we do?
According to httparchive.org, the average website on desktop is about 4 times as large as in 2010. On mobile, where data transfer is way more expensive in terms of energy usage, the numbers look even worse: from 200 kB up to a whopping 1,9 MB!
As web developers we have a responsibility to stop this madness. Did websites really get 4 times as good? Is this motherfuckingwebsite.com clocking in at 5 kB in total really that bad in comparison? I don’t think so.
Whenever you are adding to a website, ask yourself: is this necessary? If not, consider leaving it out.
I’m sorry if that turned into a bit of a rambling, but I hope you see where I am going with this. Personally I really enjoyed forcing myself not to use more than 1 kB of CSS for the website you are reading this on. It sparked creativity.
Let’s do our share as web developers and stop bloating the web.
1 Energy expenditure numbers vary a lot depending on the network you are using. “Using data volumes from the year 2010 Malmodin and colleagues estimated electricity consumption per data volume as follows: 0.08 kWh/gigabyte for averaged fixed broadband access network, compared to 2.9 kWh/gigabyte for average 3G mobile broadband access network and 37 kWh/gigabyte for average 2G mobile communication.”, doi:10.3390/su10072494