Glass Collisions

Threat Factor Table & Supporting Materials for NYC's Local Law 15

Vassar Bridge Science Building, N.Y. ©Christine Sheppard

New York City Local Law 15 of 2020 stipulates that most glass on new structures must have a Threat Factor of 25 or less to meet bird-friendly design requirements starting January 1, 2021. Below, you will find American Bird Conservancy's table of Material Threat Factors that can be used to identify acceptable materials. Materials are also listed, with photos, in our searchable database. For more information, please see our Supporting Resources, which provide further details related to bird-friendly design.

American Bird Conservancy's Threat Factor Table

American Bird Conservancy Threat Factor Table – Materials included in the Threat Factor Table have been assigned Threat Factor scores, which can range from 1 to 100. If you are interested in a particular range of scores, we recommend sorting by the Threat Factor column. The table also includes non-glass materials, as well as several products that can be used to retrofit glass.

Supporting Resources

Bird Collision Deterrence Material Threat Factor Reference Standard and Guide for Prescriptive Rating Standard describe the informational resources used to assign Threat Factor scores. This includes American Bird Conservancy's tunnel testing, testing with Klem's and Roessler's protocols, field data from monitoring programs, and descriptive criteria. We also explain the manner in which these resources were applied. NYC's Bird-Friendly Building Law: Local Law 15 of 2020, a seminar sponsored by the AIANY Committee on the environment, explores the requirements of LL15 in detail.

Bird-friendly Design and Bird-friendly Glass – A review of the ways in which bird-friendly glass can be created, including both glass patterns and external structures like sunshades. This document also includes information related to spacing recommendations and a summation of other variables.

Bird-Friendly Building Design – An overview of the threats that collisions pose to bird populations, as well as solutions for both new and existing buildings. Other topics include a summary of bird-friendly collisions legislation, a literature review of collision causes, and an introduction to collisions prevention research.

Products That Prevent Collisions

Looking for glass for a new building, or a solution to fix existing windows? Search our comprehensive material database to find the right product.

Take Action for Birds

ABC is working hard to make federal buildings bird friendly. Join us today and ask Congress to pass the Bird-Safe Buildings Act!

Visit our photo gallery to see how a variety of materials and techniques can be used to make buildings safe for birds and great for people.

News, Updates, and More

Bird Collisions on ABC's Blog

Check out BirdCalls Blog for frequent updates and insights into birds and window collisions…. Read more >>