[English Press Release] Official Launch of GreenSyncWebCO2

Buddyworks, a limited company based in Hachioji, Tokyo, Japan, officially launched GreenSyncWebCO2 in June 2025. This free tool offers a simple and practical way to visualize the carbon footprint generated when websites are loaded.

A Free Tool for Visualizing Page-Level CO2 Emissions

GreenSyncWebCO2 utilizes the Google Lighthouse API to measure the actual data transfer volume of static resources needed to render a web page—such as HTML, CSS, JavaScript, images, and fonts.
Based on this data, it calculates the CO2 emissions per page view (in grams of CO2).

For its calculation logic, the tool incorporates “co2.js,” an open-source library maintained by The Green Web Foundation, enabling reproducible and credible assessments based on internationally recognized estimation models.

The environmental rating system is inspired by the framework presented in "Introducing Digital Carbon Ratings," with practical adjustments tailored to real-world website analysis.

Key Features

• CO2 Emission Measurement
  Calculates carbon emissions per page view (gCO2).
  Example: 1.05g CO2/view
• Environmental Rating (6 Levels)
  Scores pages on a 6-point scale from A+ to F based on environmental impact.
• Page Size Visualization
  Displays total data transfer size, including HTML, CSS, JavaScript, and media assets.
  Example: 1.5MB
• Green Hosting Detection
  Checks if the hosting provider uses renewable energy via the Green Web Dataset from The Green Web Foundation.
• Annual Impact Estimation
  Estimates yearly CO2 emissions, power consumption, and equivalent offsets—such as the number of cedar trees or hours of appliance usage—based on monthly page views.
  Example (10,000 PV/month):
  
  • Estimated annual emissions: approx. 126 kg CO2
  • Equivalent CO2 absorption by cedar trees: approx. 14 trees
  • Air conditioner equivalent: approx. 390 hours

Supporting ESG and SDG Initiatives

GreenSyncWebCO2 is suitable for a variety of use cases, including:

• Providing data for ESG disclosures and sustainability reports for companies and municipalities
• Serving as a benchmarking tool for designing and improving environmentally conscious websites
• Supporting education and academic research on digital sustainability and carbon measurement

We aim to deepen collaboration with public institutions, academic communities, and green hosting providers, and contribute to the widespread adoption of sustainable web practices through potential integration with environmental certification schemes.

Toward a Sustainable Web as the Global Standard

GreenSyncWebCO2 supports your first step toward a more environmentally responsible digital future.
Start by measuring the carbon footprint of your own website.
We invite you to try it today.