Learn About NSF/ANSI 391.1 Certification Levels and Prerequisites

The standard for the professional services sector has rigorous prerequisite criteria for all applicants. Still, it allows for flexibility to further demonstrate your commitment to a sustainable future.
A picture of an adult and a child walking through grass - 391.1 Certification Levels and Prerequisites | NSF

NSF/ANSI 391.1 - General Sustainability Assessment Criteria builds on the concept of the triple bottom line, recognizing that long-term sustainability requires attention to environmental, social and economic impacts.

The standard allows professional service providers (PSPs) to make documented and measurable commitments to improve their performance in each of the standard’s four pillars: environmental impact, social equity, economic governance and supply chain sustainability.

Certification Levels and Points System

NSF/ANSI 391.1 is the only points-based ESG certification specifically designed for the professional services sector. The standard has rigorous prerequisite criteria for all applicants. However, it also provides two levels of certification and flexibility for your organization to choose additional policies, actions and practices from any of the four pillars.

Review the certification levels and points system below:

391.1 Certification Levels and Points System Chart

Required Prerequisites

Within each of the four pillars, all PSPs regardless of size, location or service area must meet all prerequisites to demonstrate compliance to NSF/ANSI 391.1. Some requirements include:


  • Publish publicly available environmental policy
  • Demonstrate a reduction of greenhouse gas emissions caused by company services
  • Increase the use of renewable energy within the corporate footprint


  • Provide documentation of ethical codes of conduct
  • Undertake recurring stakeholder mapping exercises
  • Publicly report sustainability and ESG policies


  • Commit to preventing harassment, discrimination and violence in the workplace
  • Document anti-corruption, labor, anti-discrimination and career path policies
  • Commit to support nonprofits and NGOs or provide pro bono services

Supply Chain

  • Implement supplier diversity programs and increase your spend with diverse suppliers
  • Create a diverse supply chain that supports protected class businesses
  • Establish sustainable procurement policies
  • Undertake recurring stakeholder engagement

Once a PSP has demonstrated compliance with all prerequisites, it can select additional policies and practices to gain points across the four pillars.