Carbon Offsetting

How whatsthecost.com is carbon neutral

Working out the carbon usage for this website turned out to be far more difficult than I expected. The obvious candidates are the two servers, currently two Dell PowerEdge's. One for the website, the other for the database.

But there are a whole load of other things to take into consideration. For example, I would like to take into account the carbon footprint of computers currently connected to the website. That means, that while you’re dealing with your debt, at least you know you aren’t harming the environment!

Using several guestimates and assumptions, I worked out the carbon footprint of whatsthecost.com is approximately 2 tonnes of CO2 equivalent per year. That includes the carbon footprint of its users (e.g, you as you’re using the site!), and is about one fifth of the carbon foot print for an average European family.

There is a new charity, Cool Earth, which allows people and organizations to sponsor parts of the rainforests, each acre of rainforest sponsored “locks in” approximately 100 tonnes of carbon.

So I’ve sponsored half an acre of rainforest for the website. That should lock in 50 tonnes, which should be enough for the site for the next 25 years, say 10 years if the traffic keeps increasing as it have over the last 12 months. However, I plan to sponsor an additional half an acre each year if possible.

You can view our certificate here! (Unfortunately, it’s in my name, not the website, but I did buy it for whatsthecost.com! – Looks like they don’t put the company name on the certificate)

How I worked it out! (very roughly)

Each server has a 750 watt PSU, however the CPU usage on each server is very low, so I’m going to assume (the first of many assumptions!), that each server pulls an average of 200 watts. I’m sure it won’t be more than that, and is probably significantly lower. So that’s 200 * 24 * 31 per server, which is just under 150 kilowatt hours, 300 for both.

In the last month (May 2007), the site has been used for approximately 1,450 hours – This is worked out by taking the number of visitors, and multiplying it by the average time a visitor stays on the site.

Assuming that most modern PCs draw around 100 watts when browsing the web, this means that each month, users use around 75 kilowatt hours (100 * 24 * 31).

The conversion factor for CO2 emissions is generally considered to be around 0.43, which means the CO2 emissions for the website are approximately 161.25 (375 * 0.43) kilograms per month, or just under 2 tonnes per year.