Those who work on HVACR in large buildings have always factored in safety. But in recent years, security has become as significant. To such natural threats as fire, wind, and rain, or criminal threats such as burglary and arson, has been added terrorism that may involve chemical or biological agents or dramatic acts producing mass destruction.

James Hill, acting director of the Building and Fire Research Lab at the National Institute of Standards and Technology (NIST), reviewed risk assessment in today's building planning to an audience of researchers and engineers during a plenary session Tuesday at the combined Compressor Engineering Conference and Refrigeration & Air Conditioning Conference at Purdue University.

In light of the events of September 11, 2001, Hill noted, "Terrorism involving the build environment came to America spectacularly if not frequently or widely."

He noted that the World Trade Center attacks of 1993 and 2001 have been the only ones against commercial buildings in the United States. In fact, the focus on terrorist attacks has been on public buildings, including U.S. embassies and military bases.

"Worldwide, the number of attacks on commercial buildings over the past 30 years is very small," said Hill, citing a report from an August 2003 workshop in which hundreds of persons involved in building security met to look at the issue.

That seminar produced a three-point criterion for looking at how far efforts can go in securing a building. "Protecting every building against every possible threat is not feasible. Protecting every building against some possible threats is not feasible. Protecting some buildings against every possible threat is not feasible. Protecting some buildings against some threats is feasible.

"The private sector needs to understand what buildings are at risk, what those risks are, what options are available to offset those risks, be able to choose the options that are best, and have standards for implementing those options.

"Most buildings don't need anything done to them because they are not at risk."

He said a number of government agencies have been producing manuals and publications addressing these issues in commercial construction, and reviews are underway concerning changes in codes and standards.

But Hill told the audience of engineers that any "national model codes represent minimum requirements for building construction. "It would be inappropriate to mandate requirements in the national model codes to address terrorism. But guidelines, perhaps as an appendix to a national model code, should be developed to advise state and local authorities in adapting these national codes."