What we accept as evidence of green power

We outline in more detail the process of listing providers as green, but if you are not sure about what to present as evidence we have outlined what we accept here, and our reasoning.

The general principle is as follows though:

If you want a green site, you need to demonstrate steps you are taking to avoid, reduce or offset the greenhouse gas emissions caused using electricity to provide the service. You need to do this on a yearly basis, or better.

Why we ask for this

For providers of digital services like hosting and so on, we are primarily interested about the energy from the digital infrastructure they use for evidence of greenness. We ask for this  because if we want to talk about an organisation’s digital operations being green, we need to know what makes a material difference to the carbon emissions.

This is different to things which sound nice, but do not make a significant difference to the carbon emissions of you running a digital service. As an example, composting in an office is nice, but in most cases will not make a material difference to the carbon emissions caused by running a hosting service, so it would not be enough.

Let’s run through avoid, reduce, or offset, with some concrete examples:

When we list you in the directory we share the basis you have used to account for your emissions, and we point to any public facing documentation you have agreed to make publicly available to support your claims. We do not share any supporting documentation you have asked us to keep private, but we do recommend making as much as you can available, in redacted form if need be. This makes your claims easier to defend, and some users will prefer to buy from a provider that use one way of accounting for emissions, over another.


The scenario: Your organisation draws power from renewable sources, almost all the time, and does not draw power from the grid.

An example provider: Data Centre Light in Switzerland. They have their own hydroelectric power generator, and get the rest from solar.

We need to see:

  • evidence that they have these facilities onsite to make this possible
  • a written, public claim somewhere that this is where the power comes from, not the grid.
  • If power comes from the grid, see ‘reduce’ below


The scenario: Your organisation draws power from the grid, but you take steps to reduce the share of power coming from fossil fuels. You do this by buying certificates for green energy, using a green energy tariff, or you can point to evidence of funding the deployment of renewable energy, like community solar or wind. This puts more renewables on the grid, and over time reduces the share of power that comes from fossil fuels.

Examples: Hetzner (green energy tariff), and Greengeeks (RECS), Google (both).

What we need to see:


Your organisation draws power from the grid, but you account for the burning of fossil fuels by purchasing an amount of carbon offsets that meets or exceeds the carbon emissions caused by burning those fossil fuels.

In some parts of the world, you only have a single provider of electricity (sometimes called a natural monopoly), so you can’t choose a green provider, or green tariff. Or you might use a provider who has not told you where the power used to deliver your services comes from.

In this case, we accept carbon offsets like this as a last resort.

In this case, we need a way to see the projects used, and refer to it them in the directory, but you do not need to publicly disclose the quantity of offsets purchased.

Example: You are hosting with Amazon Web Services, and using services in regions where they do not make claims about accounting for the fossil energy they use (every region apart from U.S. West (Oregon), GovCloud (U.S. West), Europe (Frankfurt), Canada (Central), Europe (Ireland)). You use the open source Cloud Carbon Footprint, to quantify the emissions caused, and you pay to account for the carbon emissions.

What we need to see:

  • the certificate from the provider of the offsets, showing a serial number or identifier for the given scheme
  • evidence of the offsets coming from a recognised scheme – VCS, Gold Standard, or a link back to the site in for users to understand the source of claims about the offsets
  • evidence of the ‘vintage’ – what time period these offsets apply to (offsets need to apply to the year of emissions – we don’t accept offsets with a vintage of 2010 for emissions taking place in 2019, for example)

If you have further questions

We currently try to balance accessibility to as many organisations as possible, with rigour – having some defensible basis for issuing our green results, and the criteria are based on principles outlined in existing, established working groups.

We also base this on published work from groups like The Renewable Energy buyers Alliance Future Internet of Power Report, and our own membership of associations like Green Software Foundation, the Open Energy project with Icebreaker One , and the Sustainable Digital Infrastructure Alliance.