(Editor's Note: Marcos Hazan-Cohen is a member of the subrogation andrecovery department at Cozen O'Connor, where he advises clientsregarding a variety of subrogation and maritimematters.)

If you live in the southern portion of the United States, youhave probably looked into different ways of lowering your energyconsumption and cooling costs during the hot summer months.

One solution that has gained tremendous popularity in recentyears involves the installation of a reflective radiantbarrier—commonly referred to as simply a “radiant barrier”—on theunderside of the roof decking. Manufacturers of these productsclaim that installing a radiant barrier on the underside of theroof decking can reduce energy consumption and save consumers asmuch as 25 percent on their air-conditioning costsannually.

With promises of huge energy savings, it should come as nosurprise that homeowners, business owners, and builders in southernstates—where the last two summers have seen record-breakingtemperatures—have started incorporating radiant barrier products intheir homes Some local governments have even gone so far asto require that all new homes be equipped with radiant barriers.What consumers and local officials do not know, however, is thatthere is a dark side to these potentially significant andsubstantial energy savings.

Recent testing performed by McDowell Owens Engineering inHouston, Texas¹ (“McDowell Owens”) indicates that thesame characteristics and properties of radiant barriers that makethem so beneficial during the hot summer months also make them asignificant fire hazard during a lightning storm. The evidencesupporting these claims is already starting to mount in states likeTexas, where a recent lightning storm produced no less than threeconfirmed lightning-induced radiant barrier fires in one area.

Fire and Lightning
To betterunderstand why radiant barriers pose a significant fire hazardduring lightning storms, one must first understand what a radiantbarrier is and how it works. On a typical sunny day, radiationfrom the sun strikes the outer surfaces of one's home or building,causing those surfaces to heat up. One of the surfaces thatabsorbs the most radiation is the roof. When the roof heats up, itbegins radiating heat inward toward the attic space, where it warmsthe attic floor. As the attic floor becomes hotter, it thenradiates heat into the conditioned space of the structure, therebymaking it harder and more expensive to cool. The radiant heat inthe attic also affects the air-conditioning ductwork because itwarms the cool air in the ductwork. When a reflective radiantbarrier is installed on the underside of the roof decking, itreduces the transfer of radiant heat from the roof decking to theattic and the conditioned spaces by reflecting it back toward theroof. As a result, consumers who install radiant barriers typicallysee a significant reduction in cooling costs during those muggymonths.

Radiant Barrier Foil Coverings
The mostcommon type of radiant barrier on the market today is a radiantbarrier foil covering. Although radiant barrier foil coverings comein many different configurations, they are all generally made thesame way. Radiant barrier foil coverings usually consist of a thinsheet or coating of highly reflective material, usually aluminumfoil, mounted or laminated to one or both sides of a substrate or acombination of substrates in layers. Common substrates includecraft paper, plastic films, plywood sheathing, and oriented strandboard. In new construction, builders will often purchasestructural sheathing that has been pre-laminated with a coating ofaluminum foil and paper. Because the pre-laminated radiant barriersheathing can be installed like conventional roof sheathing, itreduces the need for additional labor duringconstruction.

Unfortunately, pre-laminated radiant barrier sheathing is ofvery little use in older homes where removing and reinstalling theroof is usually not an option. Contractors tasked with retrofittingan older home with a radiant barrier system will often use acombination of radiant barrier products that may include aluminumfoil pre-applied to both sides of a piece of rigid insulation orreinforced sheets of radiant barrier material that can be rolledout and draped between the roof rafters using staples.

Conductors of Electricity
Regardless ofwhether pre-laminated structural sheathing, pre-laminated rigidinsulation, or reinforced sheets of radiant barrier material areused, it should come as no surprise that the aluminum laminate usedin those radiant barrier coverings makes them an excellentconductor of electricity. It should come as even less of a surprisethat a radiant barrier, attached to the under-decking of a roofsystem, has the potential to become grounded through incidentalcontact with the structure's electrical lines, plumbing lines, ventpipes, metal flashings, gutters, and HVAC lines and equipment. Oncegrounded, the radiant barrier has the potential to conductelectricity throughout the entire attic space.

In 2009, McDowell Owens performed a series of experiments withreinforced sheets of radiant barrier material to determine whatwould happen if a grounded radiant barrier became energized throughcontact with an exposed electrical conductor.² What itobserved was that, as current began to flow through the radiantbarrier material, intense heating occurred at the staples, followedby electrical arcing.³ The heating and arcingimmediately ignited the combustible substrate materials upon whichthe aluminum foil was mounted. In 2010, McDowell Owens conductedadditional experiments to observe how a grounded section ofpre-laminated radiant barrier structural sheathing would react whenenergized and heated by an electric current flow of 50amps.⁴ The results were almost identical. As theelectrical current flowed through the radiant barrier, intenseheating and fire were observed at the spot where the plywood clipjoined two pieces of pre-laminated radiant barrier structuralsheathing.⁵ McDowell Owens' experiments proved that,when a grounded radiant barrier is energized, it will catch fire.This begs the question as to how a radiant barrier installed on theunderside of the roof decking becomes energized.

A Force of Nature
Enterlightning, one of the most powerful forces in nature. A single boltof lightning can carry a charge well in excess of 30 million voltsand produce an electrical current of anywhere between 10,000 and200,000 amps. It is not difficult to imagine what would happen if aradiant barrier became completely or partially energized with anelectrical current of 10,000 amps or more as a result of a directlightning strike. More importantly, one no longer needs to imaginewhat would happen as there are plenty of real-life examples toillustrate just how devastating the damage can be when a radiantbarrier system, charged by lightning, catches fire.

While lightning-induced radiant barrier fires are much morelikely to occur in southern states where radiant barriers are morepopular and where severe lightning storms are more prevalent, theevidence is clear that any structure with a radiant barrier ispotentially at risk during a lightning storm. If that is correct,then why is so little information available about the potentialhazards associated with lightning-induced radiant barrier fires?The answer is simple: Because the radiant barrier is typically thefirst material ignited and easily consumed by fire, many fireorigin and cause experts unfamiliar with lightning-induced radiantbarrier fires fail to recognize it as a potential ignitionsource.

More importantly, many of the individuals and investigatorsinvolved with handling these losses make the mistake of assumingthat a fire following a lightning strike is nothing more than an“Act of God” and cut the subrogation investigation short. Ourfirm's own experience with lightning-induced radiant barrierlosses, as well as that of McDowell Owens, strongly suggests thatthere are more lightning-induced radiant barrier losses that arenot being properly identified or are simply being overlooked.

Fire Scene Investigation
In every claimwhere a lightning strike is alleged to have caused a fire and aradiant barrier is present, a thorough fire-scene investigationshould be done by someone familiar with lightning-induced radiantbarrier fires. Questions should be asked to ensure that the radiantbarrier has been considered as a potential cause of the fire.Similarly, one should not make the mistake of assuming that, justbecause a building equipped with a radiant barrier was struck bylightning, the radiant barrier was the cause of the fire.

A thorough analysis of the fire scene, beginning with theidentification of the lightning bolt's strike point, must beperformed to establish the actual cause of the fire and toeliminate other products that may also be susceptible tolightning-induced fires. Subrogation counsel and experts familiarwith lightning-induced radiant barrier losses and otherlightning-induced product fires should be consulted to make sureone is getting the very best guidance about how to proceed with thefire investigation and potential subrogation claim.

¹ Ron Simmons, P.E., Eric Benstock, P.E., RickBonyata, P.E. and Nestor Camera, Special Report: ReflectiveRadiant Barriers, Fire Findings, Summer 2009, Vol. 17, No.3 at7; McDowell Owens Engineering, Inc., Reflective RadiantBarriers: Good for Energy Savings – Bad For Fire Safety,mcdowellowens.com, November 5, 2010.
² Simmons, et. al., supra note 1, at10
³ Id at 11.
⁴ McDowell Owens, supra note 1.
⁵ Simmons, et. al., supra note 1, at 12.