Carbon Savings Calculation Methodology

1. Carbon Savings Calculation Methodology

The Zero2 App methodology for calculating carbon savings is designed to help users measure the impact of their green actions in 4 areas: Recycling, Green Dining, Utility Bills and Walking. Zero2 and Negawatt have applied a scientifically rigorous calculation methodology that ensures the accuracy and reliability of our carbon savings data.

Zero2 App and Negawatt has conducted extensive research studies and utilized their professional expertise to establish the carbon savings calculation methodology used in the Zero2 app. The methodology takes into account various factors such as the type of material recycled, the weight of the material, and the actual carbon emissions saved. This provides users with a clear understanding of the carbon savings resulting from their green actions.

Our commitment to scientific accuracy and transparency is essential to providing users with reliable carbon savings data. By tracking their carbon savings through the Zero2 app, users can gain a better understanding of their environmental impact and contribute to a more sustainable future.


2. Calculation Methodology

2.1 Recycling Rewards Calculation:

Type of MaterialAmount of MaterialZero Coin EarnedPositive Energy EarnedCarbon Saving (kg CO2e)
Clothing1 kg1261512.64
Paper1 kg36303.62
Metal1 kg92309.15
Plastic1 kg10300.95
Glass Bottle1 kg3300.3


The Recycling Rewards Calculation table shows the amount of Zero Coins and Positive Energy that users can earn by recycling various materials, including clothing, paper, metal, glass bottles, and plastic bottles. The table also displays the actual carbon emission saved by recycling each material. Users can use this table as a guide to help them recycle more and earn more rewards on the Zero2 app.


2.2 Daily Sustainable action

ActionZero CoinPositive EnergyCarbon Saving (kg CO2e)
No Cutlery3200.29
Bring Your Own Cup / No Cup Lid1100.11
Bring Your Own Bag16351.58
Walking (50km)151001.50


This table displays the carbon savings and rewards for sustainable actions that users can take to reduce their carbon footprint. The actions included in this table are bringing your own cup or no cup lid, bringing your own bag, and choosing no cutlery for takeaway orders. Users can earn Zero Coins and Positive Energy by taking these actions, which can be used to redeem rewards from Zero2’s partner merchants. The carbon savings are based on estimated carbon dioxide emissions that are avoided by taking these actions. Zero2 reserves the right to change the coin metrics at any time without notice.


2.3 Utility Bills Reward Calculation

Utility Bill TypeAmount of Utility Bill SavedZero Coin RewardsCarbon Saving (kg CO2e)
CLP1 kwh40.39
HKE1 kwh70.68
Towngas1 MJ10.592
WSD1 M340.428


This table shows the amount of zero coins earned and the actual carbon emission saved by saving utility bills for different types of utility companies, including CLP, HKE, Towngas, and WSD. Users can earn zero coins by saving on their utility bills and in turn reduce their carbon footprint. Each company has a different amount of zero coins earned and actual carbon emission saved per unit of utility bills saved.



3. Would you like to know more about our Zero2 App’s Carbon Savings Methodology?

If you have any questions or feedback, please feel free to send us an email at We value your input and look forward to hearing from you.

*Please note that Zero2 reserves the right to change the coin metrics at any time without notice.




  • The Greenhouse Gas Protocol: A Corporate Accounting and Reporting Standard (Revised Edition) of the World Business Council for Sustainable Development (WBCSD) and the World Resources Institute (WRI).
  • The Greenhouse Gas Protocol: Corporate Value Chain (Scope 3) Accounting and Reporting Standard.
  • The Greenhouse Gas Protocol: Technical Guidance for Calculating Scope 3 Emissions (Version 1).
  • The Sustainable Development Goals (SDGs): A set of 17 global goals adopted by the United Nations (UN) in 2015.
  • The 2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines for National Greenhouse Gas
  • Relevant IPCC Assessment
  • The International Standard for GHG Emissions ISO 14064-1: Greenhouse
  • The International Standard for GHG Emissions ISO 14064-2:2019: Greenhouse gases — Part 2: Specification with guidance at the project level for quantification,  monitoring and reporting of greenhouse gas emission reductions or removal enhancements.
  • The Avoided Emissions Framework (AEF).
  • Policy and Action Standard, an accounting and reporting standard for estimating the greenhouse gas effects of policies and
  • WARM version 16,EPA,US,
  • China Products Carbon Footprint Factors Database (2022)
  • Carbon inclusive method for the reuse of waste clothing in Guangdong Province (2022 revision).
  • CLP Power Hong Kong 2023 Sustainability
  • HK Electric Investments 2022 Sustainability
  • How to prepare an ESG Report Appendix 2: Reporting Guidance on Environmental KPIs,2022.
  • WSD Annual report20/21
  • AR6 ,GWP value,Table 7

Updated on 1 May 2024