New York City Mayor's Office of Climate and Environmental Justice

At a Glance


Government/Public Administration

Project Type

Sustainability and Energy Management Strategy




New York, NY


Allie identified and assessed greenhouse gas offset methodologies to be considered for authorization in New York City’s building emissions reduction law.


NYC’s Local Law 97 requires most buildings over 25,000 square feet to meet greenhouse gas emissions limits starting in 2024. Local Law 97 allows buildings to deduct up to 10% of the building emissions limit by purchasing greenhouse gas offsets. The law did not specify the types of offsets allowed, so the Mayor’s Office of Climate and Environmental Justice hired Allie Shepard to identify and develop carbon offset methodologies that may be authorized in the Local Law 97 rules.


Allie first surveyed the landscape of existing offset methodologies, which are essentially “recipes” for implementing offset projects and certifying offset credits. She identified several offset methodologies that may be appropriate for the specific types of offsets to be authorized but concluded they need to be revised to improve the applicability and usability for project developers. Allie mapped out the methodology revision and project development processes and discussed these with relevant stakeholders, including potential project developers, offset registries and validators, and the Department of Buildings.

Potential Impact

The city is working toward publishing the rules governing building decarbonization, and Allie helped prepare the rules and supporting justification for one of the key compliance pathways. Allie’s recommendation for carbon offsets will help advance the city’s goals of reducing city-wide emissions and improving local air quality equitably and sustainably.

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