A website with 10,000 monthly page views producing 4.61g CO2 per visit generates approximately 553 kg of CO2 per year — equivalent to driving a car 2,200 km.
How it works?
Understand our science-based approach to measuring and certifying your website's environmental impact.
Four Steps to Certification
1
Scan & Measure
Enter your website URL and we run a comprehensive analysis. We measure total data transfer, test loading performance via Google PageSpeed Insights, and assess hosting infrastructure. All measurements follow the SWD v4 model.
2
Carbon Calculation
Using the measured data, we calculate your website's carbon footprint in grams of CO2 per page view. The calculation accounts for energy consumed across four system segments: data centers, networks, user devices, and hardware production.
3
Score & Certify
We generate a composite score from 0 to 100. Websites that score above our thresholds receive a star-rated EpicStamp certificate (1 to 3 stars).
4
Monitor & Improve
Choose a 1, 2, or 3-year subscription for ongoing monitoring. Your website is re-scanned periodically with regular reports and recommendations.
Our Methodology: Sustainable Web Design (SWD) v4
We use the industry-standard SWD model version 4, developed by the Green Web Foundation.
What is the SWD Model?
The Sustainable Web Design (SWD) model is a peer-reviewed, open-source methodology for estimating carbon emissions of digital products. Version 4 was developed by Green Web Foundation, Wholegrain Digital, Mightybytes, and Medina Works.
The model translates data transfer (in bytes) into energy consumption (in kWh), and then into carbon emissions (in grams of CO2e).
The Four System Segments
The SWD v4 model divides internet infrastructure into four segments, each with its own operational energy intensity:
Data Centers
Measured intensity
The servers that host websites — compute, storage, cooling, and facility overhead.
Networks
Measured intensity
The telecommunications infrastructure — routers, switches, and undersea cables.
User Devices
Measured intensity
Laptops, phones, and tablets — energy for data processing and display.
Hardware Production
Measured intensity
The embodied energy in manufacturing hardware across all three operational segments.
Total Energy per Visit
The total energy consumption per visit is calculated by combining the energy intensities of all four segments, adjusted based on the hosting country's energy grid and visitor caching patterns.
From Energy to Carbon
We convert energy consumption to emissions using the carbon intensity of the electricity grid. It varies significantly by country:
🇫🇷
France: ~56 gCO2/kWh
(mostly nuclear)
🇩🇪
Germany: ~385 gCO2/kWh
(mixed energy sources)
🇺🇸
USA: ~379 gCO2/kWh
(varies by state)
🇳🇴
Norway: ~29 gCO2/kWh
(mostly hydroelectric)
Carbon Emissions Calculation
The energy consumption is converted to carbon emissions using the carbon intensity of the electricity grid. A website hosted in France produces roughly 7x less CO2 than one on a coal-heavy grid. Our system applies additional factors for server efficiency and caching patterns.
Returning vs. New Visitors
The SWD v4 model accounts for browser caching. Returning visitors typically load fewer resources.
Returning visitors transfer significantly less data thanks to browser caching. Our model applies dynamic caching coefficients based on the type of content served, combined with statistical visitor return patterns.
Green Hosting Bonus
If your website is hosted on a verified green energy provider, we apply a reduction factor. Green-hosted sites receive a lower carbon calculation.
PageSpeed & Quality Scoring
Beyond carbon emissions, we evaluate your website using Google PageSpeed Insights across four key areas:
90+
Performance
Core Web Vitals — LCP, CLS and TBT.
90+
Accessibility
ARIA labels, color contrast, keyboard navigation, and semantic HTML.
90+
Best Practices
HTTPS, image optimization, modern standards.
90+
SEO
Meta tags, structured data, mobile compatibility.
Each PageSpeed category contributes to your overall EpicStamp rating. Better performance means less data and less energy.
Composite Score Calculation
Your final EpicStamp score (0-100) is a weighted composite of multiple factors. The carbon footprint carries the highest weight:
●●●●
Carbon Footprint Score
Primary factor — CO2 emissions compared to industry benchmarks
●●●
Performance Score
Core Web Vitals and loading speed
●●
Accessibility
Web accessibility standards
●
Best Practices
Modern web standards and security
●
SEO Score
Search engine optimization
Star Rating System
Your certification level depends on how well your website meets sustainability requirements.
70%+ Score — Certified
Meets the baseline sustainability standard. A solid foundation to build upon.
80%+ Score — Good
Significantly above average. Strong credentials with room for minor improvements.
90%+ Score — Excellent
Among the cleanest websites on the internet. Exceptional optimization and minimal carbon footprint.
Why It Matters
4.61g
Average CO2 per page view worldwide
2%
Of global CO2 emissions come from the internet (comparable to aviation)
24/7
Continuous monitoring for every certified website
Built on Open Standards
SWD v4 Model
Developed by the Green Web Foundation. Peer-reviewed and open source.
sustainablewebdesign.orgCO2.js Library
The Green Web Foundation's JavaScript library for calculating digital carbon emissions.
developers.thegreenwebfoundation.orgGoogle PageSpeed Insights
Industry-standard tool for measuring web performance, accessibility, and SEO.
pagespeed.web.devReady to measure your website's impact?
Enter your website URL to get a free carbon footprint analysis.