Lightning Protection In The ‘Green Building’ Era
By Kim Loehr and Jennifer Morgan
The authors note that a lightning fire will typically destroy the roof and attic of a structure.
Nearly every construction project today incorporates measures for energy conservation and sustainability. Today’s project owners demand state-of-the-art “earth friendly” products and technologies for both the physical structure and the building systems. When working with earth friendly products and green technology, designers need to consider the unique threats that lightning strikes pose.
When the goal is to build a structure with a longer life-span and a smaller impact on the environment, the wisdom of protecting that structure from lightning damage should not be underestimated. A lightning fire, which will typically destroy the roof and attic of a structure, as shown in the photo, is hardly an earth-friendly event. Even if there is no direct strike or fire, nearby lightning strikes frequently cause damage to electronic systems. In many cases, surge-induced damages are not covered by property insurance policies.
Prior to the age of electronics, the threat to structures from lightning strikes was primarily fire related. The low-resistance pathways that lightning protection systems provide prevent the energy of a lightning strike from igniting structural fires. The introduction of low-voltage wiring and electronically-controlled building components presented a new vulnerability to lightning. To address these concerns, lightning protection standards were updated during the 1990’s. Additional provisions for grounding and augmented criteria for lightning arrestors and surge protection devices were added to protect building electronics.
The “green building” era presents yet another level of lightning vulnerability. Fire prevention is a green initiative in its own right, since burning structures present a serious hazard to the atmosphere and rebuilding after a preventable fire increases a structure’s energy footprint substantially. Many eco-friendly building components, such as bamboo flooring, cedar shingles and resin countertops are both flammable and costly to replace. A lightning protection system will prevent a lightning ignited fire from destroying the green structure and contents.
Green buildings also use sophisticated energy collection methods that can be damaged or destroyed by direct and nearby lightning strikes. Of particular importance are wind and solar energy collection systems, which present a unique set of considerations for lightning damage. Not only do these systems typically involve elevated structural elements that need to be protected from direct lightning damage, but they also contain costly bearings, gearboxes, electrical systems and electronic controls that are vulnerable to direct and transient lightning damage.
Solar systems - The upfront cost of incorporating active or passive solar energy collection is significant. Measures to protect this expensive equipment from lightning damage should be standard practice when designing these systems. The first consideration should be the protection of any rooftop-mounted equipment from direct lightning strikes. A UL-listed lightning protection system can be designed to prevent lightning from arcing to this equipment and damaging it. Solar collection equipment that is mounted remotely from the structure can similarly be protected from direct lightning strikes.
Equally important is the need to protect the equipment within the building that is collecting, storing and distributing the solar energy or heat. This equipment is often directly tied to a structure’s electrical system and provisions must be made to protect it from lightning surges. Code-compliant bonding provisions as well as properly selected surge suppression devices are necessary for keeping this equipment safe. Surge suppression, bonding and grounding provisions are equally important whether the solar equipment is situated on or near a structure, since buried lines are particularly vulnerable to travelling lightning currents.
Wind systems - Damage to wind turbines from lightning has been recognized as a growing problem by the National Fire Protection Association (NFPA) and the NFPA 780 Technical Committee on Lightning Protection. The increasing number and height of installed turbines throughout the U.S. has led to a rise in lightning-related incidents to these structures. Lightning strikes to these towers can explode blades, sending flaming chucks of debris hundreds of feet in the air. While blade damage is the most expensive and disruptive damage caused by lightning, the most common damage reported is to turbine control systems, which can be caused by direct and indirect lightning surges. Although wind turbines present unique challenges due to their height and construction of insulating composite materials (glass fibers, reinforced plastic and other nonconductive materials), it is possible to protect these structures through the installation of a fully integrated lightning protection system.
To limit damage from lightning, the tower and blades need to be provided with lightning protection as well as bearings, gearboxes and the electrical and control systems. Like solar energy systems, the equipment used to store and distribute the energy generated by the windmills must be protected from lightning surges. The 2011 Edition of Standard NFPA 780 contains a new chapter that contains provisions that specifically address how to protect Wind Turbine Systems from lightning. According to the new Chapter 9:
“Because the nacelle, hub, tower and base structure sections of the wind turbine typically house electrical and mechanical control systems, consideration shall be given to the protection of these systems with bonding, shielding, and surge protection.”
Lightning protection specialty contractors can work with project planners and building owners to make certain that lightning protection system designs take into account the unique hazards that green and sustainable building methods and materials can present. Lightning protection specialists will make certain that appropriate measures are taken to make sure fire hazards are mitigated and that a structure’s production and storage of electricity is not interrupted when storms roll through. When selecting a lightning protection professional to work with, be sure to verify that the firm is listed with Underwriters Laboratories as a lightning protection installer and is also a member of the Lightning Protection Institute.
About the authors:
Kim Loehr is a Principal of Loehr Lightning Protection in Richmond, VA. She is also the Communications Director for the Lightning Protection Institute, Partnership Member of the NOAA/NWS Lightning Safety Awareness Team and NFPA Building Fire Safety Systems Section (BFSSS) Member. Email: email@example.com.
Jennifer Morgan is an owner of East Coast Lightning Equipment, Inc. in Winsted, CT. She is also the Education Coordinator for the not-for-profit Lightning Safety Alliance. Email: firstname.lastname@example.org.