There are several factors to consider in this calculation, and different calculation methods and factors are used around the world, although all arrive at roughly the same result within a limited range. We have chosen to employ a calculation method that arrives at higher results than average and is based on the worst-case scenario, which ensures that all the calculations include a ‘buffer’ that helps ensure that it is always possible to offset the calculated CO2 emissions. In practice, what this means is that it may be possible to find projects similar to ours in various countries that can offer carbon offsetting at a slightly lower cost. The reason why we choose to employ a calculation model that takes into account the worst-case scenario is because the way we see it, when a business chooses to do something for the environment and take social responsibility, it is far more important that these goals are achieved rather than saving a little money by opting for a cheaper and different approach. Essentially, in order to calculate a website’s carbon footprint, you need data on a few specific areas such as the amount of power consumed by its users, the server, data transfer, etc. Regarding the energy consumed by the website users, this naturally depends on several factors such as the kind of hardware used (PC, monitor, router, modem, etc.) and not least, how much time they spend on the website and the number of page views. The starting point in our calculations is a user who uses standard hardware, which results in 173W (source: eu-energystar.org), onto which we add 30W for the power consumed by the modem and router. As for the number of page views, that is information we require from the businesses themselves, as it is not publicly available data. Of course, it is always difficult to predict the future, which is why we arrive at a solution model based on the historical level of activity and consumption over previous months which then applies for one year. Should activity/consumption levels change over the course of that year, the model can be adjusted, and the offset intervals you choose from ensures that a ‘buffer’ has always been incorporated into the calculation.
A website that has 150,000 page views a month is in the same interval as websites with up to 250,000 page views per month, which always ensures that businesses sign up for an offset level that in reality is higher than their website’s actual carbon footprint.
As for the time spent on the website, which has a big impact on the power consumed by the user, this is also an important variable in the calculation. Numerous studies have been conducted in this area by many of the world’s leading research institutes, and the results show that a website visitor spends just under one minute per page view.
We always calculate a visiting time to just over a minute, giving us an additional ‘buffer’.
Regarding the energy consumed by servers, the vast majority of businesses outsource hosting of their websites to professional web hosts. In practice, this means that even though the energy needed to run the powerful servers – which operate 24/7 – is high, the net consumption is lower because a lot of websites are hosted on the same server, which naturally results in less power consumed per website compared to the alternative, which is a single website hosted on a single server, which typically amounts to 200W.
We assume the worst-case scenario, where we use 200W in our calculations.
In addition to all this is the energy consumption for power from cables, etc. from the server to the consumer. Estimates vary in terms of how much this amounts to, but we have chosen to set this at 2W per page view, which is twice as high as what similar providers set this variable at. In other words, we incorporate a larger buffer value in this regard. The power supply and how it is produced has a major significance on the calculation of your website’s carbon footprint. Naturally, power that is derived from wind turbines, for example, adds almost nothing to your carbon footprint, whereas in contrast, coal power will add a lot. Utilities generally choose to include power produced by wind turbines in their calculations on how much CO2 they emit from their power production. For instance, if 20% of their power is derived from wind turbines, they deduct this percentage from the total, which would amount to under 600g of CO2 per KWh.
In our worst-case scenario, all the power is produced by coal, which increases the carbon footprint to 800g per KWh, which is the value we use in our calculations.
All our carbon footprint calculations are checked and approved by the national authorities of the countries where we are represented.