Circular IT series - Cloudinary: Small changes to cut bandwidth lead to big CO2 savings

A website’s CO2 footprint 

However, determining a website’s CO2 footprint can be quite complex. 

The Website Carbon Calculator bases its calculations of a website’s CO2 emissions on five different data points:

• the data transferred over the wire when a web page is loaded; 
• the energy that is used at the datacentre;
• telecoms networks
• end user’s computer or mobile device; 
• the energy source used by a datacentre; and the carbon intensity of electricity and the website traffic.

According to Wholegrain Digital, which runs Website Carbon Calculator, the average web page tested produces 1.76 grams CO2 per page view. For a smaller website with 10,000 monthly page views, that’s already 211 kg CO2 per year. But many eCommerce sites will have far more visitors. Plus, any organisation that relies on online sales is naturally aiming to increase, not reduce, its web traffic.

Fortunately, there is a way to reduce the data transferred per web visitor – bandwidth reduction. Many companies are doing this already to reduce their costs and increase their web performance, but might have not analysed this from a CO2 perspective.

The power of bandwidth reduction

Bandwidth refers to the total amount of data transmitted over an internet or network connection in a given amount of time. Bandwidth is a factor of the number of visitors that a website attracts and the file sizes that comprise a website. Let’s have a look at how reducing the bandwidth of an image and video-rich website of the largest sportswear manufacturer in Europe is making an impact on its CO2 emissions.

But before we do this, we need to explain the numbers. 

According to the American council for an Energy-Efficient Economy, it takes 5.12 kWh of electricity per gigabyte of transferred data. And according to the department of energy, the average US power plant expands 600 grams of carbon dioxide for every kWh generated. By those numbers, transferring 1 GB of data produces 3 Kg of CO2.

By using image and video optimisation tools, it is possible to reduce the bandwidth at the website’s end. In this context, optimisation refers to delivering images and videos with the smallest possible file size while maintaining visual quality. Optimising images and videos saves bytes and thus reduces bandwidth: the fewer bytes per asset, the lesser bandwidth is required. Advanced image and video optimisation tools use AI to automate this process.

1890 tonnes of Co2 saved by just optimising videos.

By deploying such automated video optimisation, a top international sports apparel brand was able to reduce bandwidth consumption by 40% from 6.8 TB/day to 4.05 TB/ day. Annualised, the company saved 618 TB of bandwidth, which equals 1890 tonnes of CO2 saved.

Bandwidth tips to reduce CO2 footprint

Certainly, the easiest way to optimise images and videos is by using automation. AI-based tools automatically set the optimal file format, file size, compression rate and visual quality for an image or video ‘on-the-fly’, ensuring as little bandwidth as possible is used but still enough to display well on your visitors’ devices.

If you don’t use such a tool, there are still several things you can do to save bandwidth:

Use smaller, lightweight image formats and video codecs for frequently used images and video.

Lev-Ami: Box clever & don’t get banjaxed by bandwidth.

Some file formats require less bandwidth than others. For example, newer image formats like WebP, AVIF, JP2, HEIC and JPEG XL can cut bandwidth requirements significantly. Using JPEG XL over JPEG, for example, could cut global data usage by 25 to 30 percent. The same applies to video codecs. 

The AV1 codec was designed specifically to improve video transmissions over the Internet. It does this by compressing videos more efficiently, thus it uses up to 20-50% less data than the video codec H.264 or H.265. As compressing newer codecs is CPU-intensive, it should be reserved for frequently used images and videos so what is gained on bandwidth savings isn’t lost on CPU power.

Use compression & caching

Compression can not only be used to reduce the file size of images or videos, but also to reduce the size of other objects of a website. For example, HTTP compression for text-based content or compression to optimise JavaScript or CSS code.

Caching works by creating a temporary storage area (or cache) that mirrors a site or application’s content. That means that the web server does not need to request the content from the backend server each time a visitor comes to your site. Caching reduces bandwidth load. If you use a content delivery network (CDN), a system of distributed servers across many datacentres, the cache can be placed even closer to the users and reduce the traffic even further and with it the CO2 footprint.

Lazy loading

Lazy loading loads heavy elements of a website (usually an image or a video) only when needed. For example, images or videos further down on a website are only loaded if the user scrolls down. With lazy loading, less data needs to be transferred and thus less energy is consumed.

Use datacentres that use renewable energy: CO2 emissions coming from the electricity generation depends among other factors on the type of fuel used. (e.g., natural gas, coal, wind, sun, water). Several studies have shown that renewable energies such as wind and sun reduce CO2 emissions. A study by the National Renewable Energy Laboratory found that generating 35% of electricity using wind and solar in the western U.S. would reduce CO2 emissions by 25-45%. Check out The Green Web Foundation database to see if your datacentre is using green energy.

Of course, sustainability is a complex puzzle and reducing the emissions of your website is just one piece of it. But as more and more of our lives move online it’s hardly insignificant. Neither is saving 1890 tons of CO2 per year. Everything businesses can do to cut bandwidth takes us that bit closer to meeting our COP26 goals. 

The good news is that small adjustments can have a big impact.