When you check your website’s carbon footprint using popular online tools, you might notice that “green-hosted” sites often get a better score than others. At first glance, this makes sense – if your hosting provider uses renewable energy, surely your site’s emissions are lower?
But here’s the catch: every website on the internet draws electricity from the same energy grid in real time, whether their host buys renewable energy or not. That grid’s carbon mix changes constantly – sometimes it’s clean, sometimes it’s fossil-fuel heavy. The real question is: should a site’s footprint be measured on marketing claims or actual electricity in use right now?
Most calculators follow a simple process:
Estimate the energy used to load your page.
Apply a static average grid carbon intensity – for example, 475g CO₂ per kWh.
Reduce that score if your hosting provider is listed as “green” in the Green Web Foundation directory, meaning they’ve purchased Renewable Energy Certificates (RECs) or Guarantees of Origin (GoOs) to match their electricity use.
This creates a lower emissions score for green-hosted sites – even though the electrons powering their servers may come from the exact same mix of coal, gas, wind, and solar as any other site on the grid.
RECs and GoOs are legitimate market mechanisms. When a renewable energy generator produces 1 MWh of electricity, they can sell the “green” attribute of that electricity as a certificate. Hosting providers can buy enough certificates to match their energy use, allowing them to claim they run on 100% renewable energy.
This supports renewable projects financially, and over time can help build more clean energy capacity. But here’s the important bit — it doesn’t change the physical electricity flowing to your server right now. The grid doesn’t send “green” electrons to one customer and “brown” electrons to another; it’s all mixed together.
From a climate perspective, what really matters in the moment is how clean or dirty the grid is right now. In the UK, for example, the carbon intensity can be under 100g CO₂/kWh on a windy night, and over 400g CO₂/kWh on a still, gas-heavy afternoon. That’s a fourfold difference in emissions for the exact same website visit – something static averages and certificate discounts can’t capture.
This isn’t to say green hosting is meaningless – far from it. By buying RECs or GoOs, hosts contribute to renewable energy projects, which helps the grid decarbonise over the long term. That’s worth celebrating and encouraging.
However, in carbon reporting terms, there’s a difference between:
Location-based emissions — the actual CO₂ per kWh from your grid right now.
Market-based emissions — your net emissions after accounting for renewable energy purchases.
Both numbers tell part of the story, but they shouldn’t be confused.
We believe transparency is key. That’s why we believe tools should show the real-time, location-based score – the immediate impact of a site visit – not a made up figure that makes websites look like they are in a better place than they actually are.
This way, you see the true footprint now, and know exactly what the impact is now.
It’s about giving you the facts, not just the feel-good figure. Because when it comes to tackling the climate impact of the web, honesty builds trust, and trust drives real action.
