From shorter answers to lower emissions: launching PromptZero in New York

During Climate Week NYC, we joined PromptZero to launch a free AI chat tool designed to reduce the emissions associated with everyday AI responses by an estimated 56% on average.

AI is becoming part of everyday working life, from drafting marketing copy to answering questions and analysing information. As adoption grows, so does the need to understand its environmental impact and find practical ways to reduce it.

At 51toCarbonZero, we helped develop PromptZero and the methodology behind its estimated carbon savings. Launched ahead of Climate Week NYC, the tool gives people a simple way to use AI more efficiently and see the estimated impact of that choice.

A simple idea: make every word count

PromptZero began as a prompt that users could copy and paste into their preferred AI platform to encourage more concise responses.

The new tool takes that idea further, turning it into a standalone AI chat interface built on Claude. Users can ask questions as they would with other AI assistants, while PromptZero is designed to reduce unnecessary output and the energy associated with generating it.
Beneath each response, users can see an estimate of the CO₂ saved, alongside a running total for their session. It is free to use and requires no sign up.

The research behind the estimated 56% saving

Making climate impact visible requires a clear methodology. Our team developed the approach underpinning PromptZero’s carbon saving estimates, testing typical workplace prompts across six industries.

The study, conducted in English using Claude Haiku 4.5, found that PromptZero reduced estimated CO₂ emissions by an average of 55.6% compared with standard, more verbose responses on the same model.

The largest estimated reductions were:

59% for marketing and advertising
58.7% for food and beverage
57.3% for general office use

The methodology uses EcoLogits, an open source tool for estimating the environmental footprint of AI, and will be rerun every six months as models evolve.

The savings displayed in the interface are estimates based on the study’s average reduction. PromptZero applies that average to the estimated footprint of each answer, rather than generating an additional response for comparison every time someone submits a query.

Bringing the idea to the streets of New York

Climate Week NYC provided an opportunity to bring this practical approach to a wider audience as conversations explored AI’s environmental impact and rising electricity demand.

Alongside the launch, PromptZero featured in a digital public service campaign across LinkNYC kiosks and digital bus shelters throughout Manhattan. The campaign brought the idea of more efficient AI use into everyday public spaces, with messages including “Welcome to Climate Week. Let’s Keep This Brief” and “Prompt Like There is Tomorrow”.

The campaign was supported by the Earth Public Information Collaborative (EPIC), 51toCarbonZero, Impact BBDO and Horizon Media.

Small changes with the potential to add up

Addressing AI’s environmental impact involves decisions across infrastructure, technology and everyday use. PromptZero focuses on an action people can take whenever they ask an AI assistant a question.

As our CEO and Co founder, Richard Davis, explained at the launch:

“Generating shorter answers sounds like a small thing, but when AI is being used at enormous scale, those savings can quickly add up.”

For us, the project reflects a wider principle behind our work at 51toCarbonZero: helping people turn climate data into practical action. By making estimated savings visible, PromptZero connects an everyday behaviour with its potential environmental impact.