I am nervous about writing this post; no doubt the lobby groups that promote plastics and fossil fuel use and hate green building will jump on it. However, when the National Fire Protection Association analyzes a fire one has to pay attention. Last May 14, a fire started in the headquarters of Organic Valley Natural Foods in La Farge, Wisconsin, that took out a good portion of the building.
It was a pretty green building, with engineered wood construction, denim insulation, a roof covered in photovoltaic panels and wet sprinklers throughout the occupied spaces, dry sprinklers in the attic. Really, just what the TreeHugger would have ordered.
One of the first things that firefighters often do is chop a hole in the roof to get the smoke out. However there were 70 Kw of photovoltaics on the metal roof and it soon became clear that the whole thing was shorting out.
Some of the PV arrays were beginning to deform and collapse into the attic space. A reading was taken to see if any electric current was being directed through the metal roof, and 50 volts of direct current — enough to shock and possibly kill a person, under certain circumstances — was found to be moving through the metal panels.
So they didn't want to go on the roof. Then the deformed roof broke the dry sprinkler system, causing water to empty into the building and draining the city water system, so they had to bring in tankers of water. Author Robert Duval describes how the fire spread and makes a controversial statement, the start of what seems to be a criticism of green building:
Fire travel was also a big concern; the fire had reportedly started inside the end wall of the west wing and had moved vertically and horizontally inside the walls, beyond the reach of sprinklers, to eventually involve the entire wing. That pattern of travel raised questions about the combustibility of the cotton-denim insulation, as well as questions around the presence, and effectiveness, of fire blocking elements inside the walls. It was apparent that a variety of "green" or "sustainable" building methods, materials, and systems had contributed to a large, dangerous fire.
He then looks at the contributory causes, including:
1 Lightweight framing: This is used by a lot of people these days, not just green builders. Duval writes:
The use of lightweight-type construction in all kinds of buildings today is common — the use of "engineered" lumber and metal structural members is marketed as more environmentally friendly (as well as less expensive) than dimensional lumber, and they can be found in many types of occupancies. Left unprotected, these lightweight elements can fail much faster than dimensional lumber when exposed to fire, increasing the risk of death or injury to firefighters and building occupants.
It may be more environmentally friendly, but it is also cheaper, which is why everyone is using it. That is hardly a failure of "green" building."
Natural Fiber Insulation or Building Components:
A variety of renewable and recycled materials were used in the Organic Valley building construction, including its insulation, which was manufactured from post-consumer recycled denim and treated with a non-toxic mold and mildew inhibitor. While the cotton-fiber material provides an insulating value similar to that of conventional fiberglass insulations, which are noncombustible, it is also combustible under certain conditions. At Organic Valley, the cotton insulation played an important role in the fire’s travel through concealed wall and ceiling spaces.
I personally have never been convinced that denim insulation is particularly green, but that is another story. I certainly wouldn't have thought it was a fire hazard in a fully sprinklered building. Something obviously happened here that caused the sprinklers to be ineffective, and that's not fully explained in the article. Duval writes:
Investigation of the Organic Valley fire confirmed that the building’s sprinkler system worked as intended, but that its effectiveness was compromised by the circumstances of the fire. Sprinklers operated within the building, including the attic, but due to the vertical and horizontal fire travel through the concealed spaces of the building’s west wing, not all of the suppression capabilities of the sprinklers were realized.
So what does that actually mean? That the sprinkler system wasn't properly designed? It makes no sense to me. Again, is it an indictment of green building? Or of using combustible insulation, when there are non-combustible green alternatives?
In the Organic Valley fire, the decision was made early not to commit firefighters to the roof of the building for ventilation operations. This turned out to be an accurate risk assessment when it was later discovered that the roof deck was being energized by the PV arrays contacting the metal roof panels, a result of the collapse of the building’s roof system. Both suppression and overhaul efforts were complicated by the fact that the PV system continued to generate electricity.
This is not a new issue. Even the NFPA says "The safety of fire fighters and other emergency first responder personnel depends on understanding and properly handling these hazards through adequate training and preparation."
The International Association of Fire Fighters has made a series of recommendations that could have been followed, including:
The next-time you work a solar fire remember the following tips to protect yourself: Cover solar arrays with performance proven heavy tarps.
Disconnect inverters and operate away from the energy source.
Never remove photovoltaic panels or break them to ventilate a roof. Use alternative methods such as accessing the gable, or Horizontal Ventilation, if there are no ventilation paths provided.
Duval concludes that "The challenges encountered in the Organic Valley fire underscore some of the broader fire safety issues presented by sustainable building practices." Indeed any new technology, green or not, requires training and education. The Organic Valley fire was, as Duval suggests, a "perfect storm" of contributing causes. Let's just hope it isn't used as an indictment of green building, because it's not.
Read the whole thing in NFPA Journal.