Almost every host now claims to be green. The claims are not equivalent — here is the hierarchy, from carbon negative to a certificate someone bought.
Data centres consume somewhere around 1–2% of global electricity, and every hosting company now has a sustainability page. The claims range from structurally meaningful to almost entirely cosmetic, and the marketing copy makes no distinction. Here is the hierarchy.
Tier 1: reduce the energy used
The only intervention that unambiguously helps is using less power in the first place. This shows up as PUE (power usage effectiveness) — total facility power divided by IT equipment power. A PUE of 1.1 means 10% overhead for cooling and losses; a badly-run facility is 1.8 or worse.
OVHcloud is the standout: it designs and builds its own water-cooled servers, avoiding air conditioning almost entirely, and reports PUE figures around 1.1. Hetzner and Nordic operators benefit from cold climates and direct free cooling. This is engineering, not accounting, and it is the tier that matters most.
Tier 2: buy actual renewable power
A power purchase agreement or a genuine renewable tariff means the electricity going into the building came from renewable generation. Several UK hosts do this — Krystal, 34SP and IONOS among them — and it is a real, verifiable commitment with a real cost attached.
Krystal goes further than most: B Corp certified, 100% renewable, and carbon negative through additional removal purchases, with the ownership structure (an employee trust) to make it stick rather than being a marketing cycle.
Tier 3: renewable energy certificates
This is where it gets murky. RECs and REGOs are tradable certificates representing renewable generation somewhere on the grid. Buying them lets a company claim renewable electricity without any change to what physically powers its building.
GreenGeeks' "300% renewable" claim is this — buying three times the certificates for the power consumed. It is better than doing nothing and it does fund generation at the margin. It is not the same as a facility that runs on renewable power, and the two claims read identically in an advert.
Tier 4: carbon offsets
Paying someone else to plant trees or avoid emissions elsewhere. The voluntary offset market has a well-documented problem with additionality — a substantial proportion of credits studied have turned out to represent reductions that would have happened anyway. Treat "carbon neutral through offsets" as the weakest claim on the list.
What to actually look for
- A published PUE figure. Companies that measure and publish it are usually the ones doing the engineering work. Vagueness here is informative.
- "Renewable-powered" versus "carbon neutral". The first describes the electricity. The second usually describes an accounting adjustment.
- Third-party verification — B Corp, ISO 14001, or a published sustainability report with numbers rather than adjectives.
- Whether they own the building. A host reselling space in someone else's facility can only pass on that operator's efficiency, whatever their own marketing says.
The uncomfortable part
The largest environmental variable in web hosting is not which host you pick. It is how much compute your site wastes. A bloated WordPress site with a page builder, forty plugins and unoptimised 4 MB hero images burns several times the CPU and bandwidth of a lean one — on every single page view, on every visitor's device as well as the server.
Caching properly, compressing images to WebP and deleting plugins you do not use will reduce your site's actual footprint more than switching between two hosts that both claim to be green. It also makes the site faster, which is the rare case where the environmental argument and the self-interested one point the same way.
Published 12 August 2026. Prices and ownership change — check the comparison table for current figures, and the provider's own site before buying. No affiliate links anywhere on this site.