The Leadership in Energy and Environmental Design (LEED™) Green Building Rating System represents the U.S. Green Building Council’s effort to provide a national standard for what consistitutes a “green building.” Through its use as a design guideline and third-party certification tool, it aims to improve occupant well-being, environmental performance and economic returns of buildings using established and innovative practices, standards and technologies.Consistent with USGBC policy for the continuous improvement of LEED, Version 2.1 is an administrative update of the LEED 2.0 Rating System for new commercial construction, major renovations and high-rise residential buildings. Its purpose is to address concerns raised by USGBC members and other LEED users by providing technical clarifications and streamlining the documentation requirements for LEED certification. These improvements are expected to simplify the documentation process for project teams and to reduce the costs of documenting LEED credits while retaining the stringency and integrity of the LEED Version 2.0 standards. An approval vote by USGBC membership is not required for Version 2.1 because performance levels have not been altered. Version 2.1 was created through the generous volunteer efforts of the LEED Technical Advisory Groups and with the guidance of the LEED Steering Committee. This document represents general consensus, not unanimous agreement. USGBC gratefully acknowledges the contributions of its committee members.The new LEED Letter Template is a central component of the Version 2.1 improvements. It is a dynamic tracking and documentation tool that must be used by Version 2.1 project teams in preparing a complete LEED certification submittal. For each credit, the Letter Template prompts LEED practitioners for data, indicates when documentation requirements have been fulfilled adequately for submittal, and serves as a formatting template for the project’s initial submittal. Additional support documents will be requested during the certification assessment’s audit phase.This Rating System document states the basic intent, requirements and documentation submittals that are necessary to achieve each prerequisite and voluntary “credit.” Projects earn one or more points toward certification by meeting or exceeding each credit’s technical requirements. All prerequisites must be achieved in order to qualify for certification. Points add up to a final score that relates to one of four possible levels of certification. See the LEED Checklist for a summary of credit topics and point values. A short description of technologies and strategies is included for each credit to briefly inform those who are unfamiliar with the particular topic. The LEED Reference Guide for Version 2.1—the technical companion to the Rating System and Letter Template—provides further background, explanations and instructions.