Validation: High Carbon Rating

back to issues overview

High Carbon Rating

URLs that have a carbon rating of D, E or F using the digital carbon ratings system from Sustainable Web Design.

This scale equates page weight tracked by the HTTP Archive with CO2 estimates per page view. The CO2 calculation uses the ‘The Sustainable Web Design Model’ for calculating emissions, which considers datacentres, network transfer and device usage in calculations.

The CO2 calculation and rating system can be used as a benchmark, as well as a catalyst to contribute to a more sustainable web.

Please note: Estimating carbon emissions of a website is difficult, and the tools used to do so are not perfect. However, it is a good starting point for businesses that wish to monitor and improve their carbon footprint. This is not something that will improve your SEO.

How to Analyse in the SEO Spider

To populate this filter JavaScript rendering must be enabled via ‘Config > Spider > Rendering > JavaScript’.

View URLs with this issue in the ‘Validation’ tab and ‘High Carbon Rating’ filter, and export all URLs using the ‘Export’ button.

Use the lower ‘Resources’ tab tab to see the individual ‘Transferred’ sizes of resources loaded on a page to identify those contributing to overall page size.

Consider performing a page speed audit to identify opportunities for reducing the weight and improving the speed of pages.

What Triggers This Issue

This issue is triggered when a URL is assigned a carbon rating of D, E or F using the digital carbon ratings system from Sustainable Web Design.

Digital Carbon Rating Scale

This equates to any page larger than 1875kb in total transferred size, which is 0.656 grams of CO2 per pageview.

The ‘Total Transferred’ size of a web page is used to calculate CO2 emissions, which includes all loaded resources when in JavaScript rendering mode.

How To Fix

Consider optimisation opportunities to reduce file size and CO2 emissions, and improve carbon footprint and rating.

The CO2 calculation and carbon rating can be integrated with analytics data to help prioritise which areas or URLs should be focused upon.

Review best practices and opportunities listed under the PageSpeed tab for more specific actions.

Further Reading

Back to top