Emergency Egress From Buildings. Part 1. History and Current Regulations for Egress Systems Design. Part 2. New Thinking on Egress From Buildings.
Emergency Egress From Buildings. Part 1. History and
Current Regulations for Egress Systems Design. Part 2.
New Thinking on Egress From Buildings.
(1972 K)
Bukowski, R. W.
Performance-Based Codes and Fire Safety Design Methods,
7th International Conference. Sky is the Limit.
Proceedings and Case Studies. April 16-18, 2008,
Auckland, New Zealand, Society of Fire Protection
Engineers, Bethesda, MD, 167-191 pp, 2008.
Keywords:
performance based codes; fire safety; safety
engineering; regulations; egress; emergencies; systems
engineering; stairways; stairwells; elevators (lifts);
flow rate; geometry; high rise buildings; human beings;
technology utilization; refuge; design applications;
occupants; evacuation; specifications; data analysis;
performance evaluation
Abstract:
For most of history buildings were short enough that
stairs provided for access were sufficient for rapid
egress in the event of fire. Even in single stair
(mostly residential) buildings, experience showed that
this stair was sufficient for fire egress as long as the
fire did not expose or block access to the stair. Fire
resistant apartment doors shielded the stair from most
fires and exterior fire escapes provided a second egress
path beginning early in the 20th Century. The 1854
invention of the elevator safety brake enabling the
passenger elevator is credited with facilitating
increases in building height and the first so-called
skyscraper in Chicago in 1885. These buildings utilized
steel frames protected by masonry or tile and were
dubbed "fireproof construction" providing a (possibly
false) sense of security. By 1914 authorities had begun
to question these arrangements as evidenced by a move to
change the term "fireproof" to "fire-resistive," and
description of egress provisions in regulations as
"exceedingly deficient." Model building regulations in
the US started with the National Building Code published
by the National Board of Fire Underwriters (NBFU)
following the Great Fire of Boston (1872). Property loss
claims from this fire resulted in more than 70 insurance
companies being driven into bankruptcy, causing
insurance interests to form the NBFU and to develop
building fire safety rules aimed at reducing property
losses in fires. These rules became the first model
building code, called the National Building Code (NBC),
and first published in 1905. The NBFU was able to tie
compliance with their rules to their Municipal Grading
Schedule on which insurance rates are based. Cities
needed favorable rates to attract investment, so they
were motivated to adopt regulations consistent with the
National Building Code. The first (1905) edition of the
NBC required exit stairs to have a minimum width of 20
in (510 mm). The purpose of this paper is to document
current regulatory requirements for means of egress in
fires, their origins and scientific basis, and the
approaches used in other countries. Then the paper will
present an argument for why these approaches and
requirements should be re-evaluated to reflect changes
both in buildings and in their occupants. Finally the
paper will make some suggestions for reasonable
revisions to design practice along with a more holistic
philosophy that takes better account of human behavior
and is based on a more appropriate performance metric.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899