Green hosting: what's real and what's a certificate

Every server your site touches is a physical machine drawing power, in a building that has to be cooled. Data centres account for roughly 1.5% of global electricity consumption — comparable to the aviation industry — and the internet as a whole for something close to 4% of carbon emissions.

So “green hosting” is not greenwashing as a category. But some of it is, and the distinction is learnable in about five minutes.

The distinction that matters

Two very different things get marketed with the same word.

Renewable Energy Certificates (RECs) are bought after the fact. A provider uses grid electricity, then purchases certificates representing renewable generation somewhere else. It is accounting. It is not nothing — it does fund renewable projects — but the electrons powering your server were whatever the grid was producing that day.

Power Purchase Agreements (PPAs) are contracts to buy the actual output of specific renewable generation. This is a materially stronger claim, because it funds capacity being built rather than reallocating credit for capacity that exists.

The strongest claim of all is 24/7 carbon-free energy: matching consumption with carbon-free generation hour by hour, rather than averaging it across a year. Averaging lets a provider run on gas overnight and call the year renewable.

If a host's sustainability page says only “100% renewable” with no further detail, that is usually certificates. Worth knowing rather than worth condemning.

Where UK businesses stand

Reasonably well served. Several UK-owned hosts run on verified renewable energy from UK data centres, some certified by the Green Web Foundation, at prices starting around £2.49 a month — which is to say green hosting is not a premium product any more.

UK data centres also help for a reason unrelated to carbon: lower latency for UK visitors, and simpler answers on data residency if you handle personal data.

The thing most people miss

Here is the part that gets skipped in every article about green hosting: the biggest carbon lever is not which host you use. It is how much your site makes them do.

A four-megabyte page loaded a hundred thousand times a year costs vastly more energy — across the data centre, the network and every visitor's device — than the difference between two hosting providers. And the energy burned on the visitor's phone is not on your host's balance sheet at all.

Which means the most effective sustainability work is the same work as the most effective performance work:

• Compress and correctly size images. This is almost always the single biggest win.
• Ship less JavaScript.
• Cache properly, so repeat visits transfer almost nothing.
• Remove the tracking scripts nobody looks at the data from.
• Serve from somewhere near your visitors, so fewer network hops are involved.

Every one of those makes the site faster, cheaper to run and better at converting. The carbon saving comes free with work you should be doing anyway — which is a much better argument than virtue.

Our own take on the performance side is in Core Web Vitals in plain English.

How to judge a host's claim

1. Does the sustainability page distinguish PPAs from certificates, or just say “100% renewable”?
2. Is there third-party verification, or is it self-declared?
3. Do they publish a PUE figure (how much energy goes to computing versus cooling)?
4. Where are the data centres, and what grid do they sit on?
5. Is there anything on hardware lifecycle — how long machines run before replacement, and what happens to them after?

A host that answers all five specifically is doing the work. One that answers none of them and plants a tree per signup is doing marketing. Tree-planting is fine; it is just not the same claim.

Our honest position

We would not tell a client to migrate purely for carbon reasons — the emissions of the migration itself are not zero, and the difference between two reasonable hosts is small next to the difference between a heavy site and a light one.

What we would say: when you are choosing anyway, choose the greener option, because it now costs the same. And spend the effort you might have spent on host-shopping making the site lighter, where the leverage genuinely is.

If sustainability reporting matters to your business or your customers, we can build a site that stands up to the question — book a free call. See also types of hosting compared.