To make your app, website, product or service carbon neutral is easier (and cheaper) than you might think!
Frankly, it’s so easy and cheap that everyone should be doing it. It feels good!
Here’s how to go Carbon Neutral.
1. Find out how much electricity is needed
As difficult as it sounds, you can use common “proxy metrics” which will give a reasonable estimate.
One such “proxy metric” you can use to derive how much electricity you need to offer your service is the amount of traffic your app or site has. Traffic in terms of (giga-) bytes.
The gigabytes (GB) your app or site generates may be an estimate itself. Unless you’ve got access to logs and monitor this carefully, you may use tools like webpagetest.org, lighthouse or similar to get an idea of how many bytes one page view generates.
From here things get a little easier thanks to other people’s efforts. There are mainly two models you can follow: the 1 byte model, “by spend” and the Sustainable Web Design model (SWD).
I’d recommend the SWD model because it’s very broad, top-down, flexible, transparent and it’s relatively compliant with other standards in the space, such as the GHG protocol for reporting scopes.
Example to estimate electricity spend
The formula used by SWD is:
Electricity = [Data Transfer per Visit (new visitors) in GB x 0.81 kWh/GB x 0.75] + [Data Transfer per Visit (returning visitors) in GB x 0.81 kWh/GB x 0.25 x 0.02]Let’s say loading a representative page on your website weighs 3 MB everything included. Your website has 1000 visits per month. 70% are new users, 30% are returning users (they have some html, css, js images etc. in their browser cache so they’re downloading only 2%).
Then the formula would be:
(0.003 GB x 0.81 kWh/GB x 0.7) + (0.003 GB x 0.81 kWh/GB x 0.3 x 0.02) = 0.00171558 kWh/visit.(The 0.81 kWh/GB and 0.02 are defaults from the SWD model and can be changed if you have better data)
To arrive at a yearly estimate for electricity needs in our example, the formula is then:
1000 visits x 0.00171558 kWh x 12 months = 20.59 kWh.2. Find out how much CO2 the electricity generate
To figure out how much CO2 emissions the 0.00057186 kWh cause, you can use services like Electricity Mapsto find the carbon intensity of electricity. This varies drastically around the globe.
In Norway, the carbon intensity of 1 kWh is 25 grams CO2e, while in India and many US states it’s well above 700 grams CO2e.
The SWD model uses a global average of 442 grams CO2e/kWh.
This number can be adjusted to where your data center is geographically located, whether it’s powered by renewable energy, and where your users are located.
Using the default, 442 g/kWh, our example looks like this:
20.59 kWh x 442 g/kWh = 9099 g CO2e = 9.1 kg CO2e.Our website has a yearly carbon footprint of 9.1 kg CO2e.
(Which is about the same as driving a modern fossil car 74.40 km)
3. Buy carbon offsets
In order to claim carbon neutrality, our example site must make up for the 3 kg CO2e.
This is done by “offsetting”. You need to buy “carbon offsets” to compensate for your emissions.
This business is, to be honest, a little prone for scams. To avoid this article being too long, I’ll just say; do research, make calls, send emails, look for companies offering projects verified by Gold Standard, Verified Carbon Standard and Climate Action Reserve. Look at google for potential places to buy.
From good vendors with good projects offsetting 1 metric tonne (MT) of CO2e costs in the range of $16 – $30.
Back to our example. What’s the cost of compensating for the emissions of our website?
0.003 tonne CO2e x $30 = $0.27 per year
…honestly, everyone can afford $0.27 per year for a site with 12000 visits per year.
Conclusion
Yes, the calculation is not accurate and not perfect. It’s a qualified guess based on the data we have available.
However, we have to start somewhere. The SWD model, the 1 byte model, or even a “by spend” models (emission by money spent running your app or site) are all great places to start figuring out the carbon footprint. The rest is so easy and so cheap that everyone should do it!