Greenhouse Gas Emissions Inventory

The Inventory of New York City Greenhouse Gas Emissions is an annual report that measures where emissions come from and tracks the City's progress in reducing them. The report consists of two inventories: Citywide and City Government.

• The Citywide Inventory reports all activities taking place within the boundaries of New York City's five boroughs.
• The City Government Inventory reports only activities associated with New York City government operations.

The inventory report is the most fundamental tool we have to measure the City's climate progress, conduct climate action planning, and showcase how human activities in New York City impact climate change.

In 2007, New York City began publishing the report and updating the inventories annually in accordance with NYC Local Law 22. Since then, the Mayor's Office of Sustainability has remodeled the inventory reporting in 2015, 2016, and most extensively in 2019 to align our accounting methods with the best available science and be in compliance with the Global Protocol for Cities. Throughout this period, the City of New York has become a global leader in the development and implementation of city-level carbon accounting methodologies.

Improving Inventory Reporting

New York City is always looking for opportunities to improve our GHG accounting methods. In the 2019 Inventory, we improved our measurement of the carbon intensity of the power grid, achieved a more complete collection of heating oil data, and reached a more efficient way to collect City Government energy data.

Electricity emission factor overhaul

The previous electricity emission measurement did not consider emissions from old, dirty generation sources, relied on datasets that are no longer available, and included out-of-date assessments of electricity generation and contracted power into New York City. 

To improve the electricity emission accounting method, the Mayor's Office of Sustainability:

• worked with PowerGEM, an expert in electricity markets modeling, to reassess how much weight to allocate electricity generation from different regions in upstate New York;


• completed a quality assurance process for the data used in our calculations of the carbon intensity of the grid for each year dating back to 2005;


• stopped the practice of assuming that 100% of contracted power made it to the City from outside Zone J of the New York Independent System Operator's Load Zone;


• included emissions from old, dirty generation sources that were not originally included in the 2005 base year calculation, specifically electricity generated from tire-derived fuels, waste oil, Municipal Solid Waste, and Petroleum Coke.

The result is a more accurate assessment of the carbon intensity of our power grid over time, dating back to 2005.

More complete coverage of heating oil sales

In 2019, the Mayor's Office of Sustainability partnered with the Department of Consumer Affairs to create a comprehensive list of heating oil vendors operating in New York City, which resulted in a broader coverage of data collection of heating oil.

The Mayor's Office of Sustainability also issued penalties to vendors that fail to report annual sales data (in accordance with Local Law 43), which has increased compliance rates.

Organization of municipal data collection

In 2018, the Mayor's Office of Sustainability shifted away from agency-based data collection and partnered with the Department of Citywide Administrative Services to consolidate data reporting from various City agencies. This new process created more consistent data and complete energy benchmarking data resources for the City Government GHG Inventory.