Are fog nozzles not the answer?
Energy-Efficient Windows (EEW)
The second justification made by Fredericks for his statement that “the fire environment is far more hostile and unpredictable than it was in the 1950s” is the presence of Energy-efficient Windows (EEW)
The presence, or absence, of windows is one building feature that plays a crucial role in fire fighting. It is still almost universally true that every room in a house has at least one window. That hasn’t changed. What is different is that instead of single pane plate glass windows we now have double pane insulated windows.
Has the presence of EEWs produced a dramatic change in fire behavior? First, it may not be common knowledge that plate glass windows (single pane) break from thermal stress early in the development of a structure fire. This begins at a temperature range of 550oF to 600oF. This temperature range is well below the temperature needed to produce flashover (1,100oF).
Much to their surprise the double pane window broke out earlier than the single pane window. There was an interesting experiment conducted by two instructors at the Rockland County Fire Training Center (N. Y.). They conducted a side-by-side test of a single pane window and a double pane window. Their test results were published in FIREHOUSE magazine. Much to their surprise the double pane window broke out earlier than the single pane window. In fact the entire double pane window fell out because of the melting of the vinyl frame. The authors did conduct a thorough search for any data or testing done on the behavior of windows in a fire, but they were unable to find any.
However, there is some information published in the 17th Edition of the NFPA Handbook in an article by Robert W. Fitzgerald, entitled “Structural Integrity During Fires.”. He makes the following statement about window glazing(glass).
“It quickly cracks because of the temperature difference between the surfaces. Double glazing does not provide much improvement. No glazing should be relied upon to remain intact in a fire.”
In fact the Rockland test detected no improvement whatsoever. So here again Fredericks claim is at odds with the facts as stated by a recognized authority in the NFPA Handbook.
