Brant Dillon, Director of MEP, Mortenson Construction, Minneapolis
CSE: What are some of the unique challenges regarding fire and life safety system design that you’ve encountered for such facilities? How have you overcome these challenges?
Grove: Many of these hotel-casinos and resorts include many millions of square feet and can be of “super high-rise” designations. The height of these buildings presents the challenge of providing adequate flow and pressure to the top of the building. This can include designing fire pumps in series to boost the pressure necessary to achieve these requirements. Many jurisdictions do not permit the use of fire protection equipment that is not UL-listed due to excessive pressures, thus requiring high-zone fire pumps mid-rise in the building. Jurisdictions in areas such as California and Southern Nevada also require that redundant fire pumps be provided once buildings exceed a certain height; generally, buildings in excess of 200 to 250 ft tall. These large projects also contain challenging fire hazards, such as high-volume spaces (e.g., atria and theaters) that require extremely high flow rates. These conditions may require multiple fire pumps to operate in parallel to achieve the required demand of the systems.
White: Egress always tends to be a challenge due to the high-occupancy loading assumptions required by the building codes, in conjunction with the rather large floor areas associated with casino buildings. Where exit capacity becomes an issue, integration of horizontal exits into the design helps to increase the amount of egress capacity, while allowing for partial-evacuation schemes so that there isn’t a total building evacuation needed under any given alarm scenario. This requires careful coordination of fire alarm notification zones as well as the zoning of automatic sprinkler protection, which sends alarm signals to the fire alarm system. Horizontal exits usually help with travel-distance issues that come with large casino-floor designs. In other instances, we’ll take advantage of high slab-to-slab elevations and we will position exit passageways beneath the slab above, which can allow egress near the center of the casino floor and provide a protected path to the exterior of the building between the false ceiling and the floor slab above the casino floor. Unique interior designs often create challenges with sprinkler coverage. Usually, performance-based sprinkler protection is required to address the obstruction challenges of the interior design. In some instances, we have created mock-ups of the conditions and run real sprinkler tests to confirm the performance of the sprinkler design meets the intent of the codes and standards.
Shino: Probably the most challenging situation is to have a large addition to an existing facility, such as a casino/resort with an existing high-rise tower that is then going to expand its podium and add a tower. High-rise provisions for one tower that was built a decade or more ago is typically not compliant with new codes and standards. Developing a scheme that incorporates modern code compliance without compromising the existing building’s fire protection features, and getting approval from the AHJ, can be complex.
CSE: What fire/smoke and security features might you incorporate in hotels, resorts, and casinos that you wouldn’t see on other projects?
Shino: In the past 20 years, smoke control for high-rise hotel/casino projects became fairly complex, with large open spaces and relatively low ceilings. Add to that an occupant load that includes one person per 11 sq ft and you have a dense occupant load with lots of plastic gaming equipment. Fire protection features for casinos must be robust.
CSE: What types of systems have you put in place to guard against natural disasters, such as hurricanes, wildfires, floods, earthquakes, etc.?
White: Typically, building structural and façade enhancements are required by the building code depending on the region in which the building is constructed. For example, casinos in Las Vegas will include structural provisions related to the high seismic potential in the area. Casinos in Macau or South Florida will include provisions to address the hurricane and typhoon zones in which they are situated. Resiliency of floors is often considered and required by certain insurance underwriters. In these instances, “berms” around the building perimeter are provided to protect underground parking areas.
Critical building systems, such as incoming electrical, fire pumps, and emergency generator power supplies, are installed above the 100-year flood plain or on floors higher than the ground floor to ensure operation under flood conditions. Using fully integrated casino resorts as storm shelters is often an initial objective in early design, but it isn’t often carried through. To be a storm shelter, one must comply with the highest hazard-classification requirements of the building code, specifically IBC Chapter 16. Casinos that are not already in high seismic zones won’t necessarily comply with the rigorous high-hazard requirements that must be met to become a storm shelter. Therefore, a casino in Massachusetts wouldn’t automatically become a storm shelter, and it is cost-prohibitive to meet these additional requirements.
Shino: Given the devastation that the United States has experienced regarding hurricanes and other natural disasters, there has been a renewed focus on confirming that buildings with high occupant loads meet the minimum code standards for both structural integrity and ensuring that emergency power systems are capable of sustaining power loads for their minimum duration. Some owners expect more, so having a minimum of 3 days’ worth of fuel for generators rather than the code-minimum amount may be requested.
Grove: Projects that are located on the West Coast are required to be designed to seismic considerations. For fire-suppression systems, this entails sway bracing and flexible couplings. Sway bracing, if designed outside of the parameters of the base code provisions, requires calculations to be performed on the type of materials for these braces and their maximum spacing. For high-rise buildings in these seismically active areas, secondary water-storage tanks are required to be incorporated into the fire-suppression systems. As these tanks are required to be designed to the most demanding sprinkler systems, it is not unheard of to have tank sizes approaching or exceeding 100,000 gal.
CSE: Describe unique security and access-control systems you have specified in such structures.
Shino: Security and access control must be balanced with life safety. Many secure facilities, such as the cages at casinos (areas where large amounts of money are handled), require secure access. Those areas may be outfitted with fingerprint scanners to limit access. Nearly every cage includes a “man-trap,” or a hallway with two doors that cannot be opened simultaneously. From a life safety standpoint, imagine having to go through two locked doors in an emergency. The fire and life safety systems have to be integrated with security systems and procedures to confirm life safety without compromising large amounts of cash.
Grove: All casinos are provided with man-traps for their casino cages and other highly sensitive areas. The issue with man-traps is that two doors must be traveled through to enter and exit these areas, and only one door may be used at a time. This is controlled by a security system. The casino operator is primarily concerned with occupants trying to enter these rooms, not necessarily those who exit. The challenge becomes that the building code requires free and unobstructed egress from all portions of the building. These access doors do not necessarily meet these requirements without additional provisions, as permitted by the building code and the local building official. Provisions can include alternate means and methods such as connecting both doors (egress direction only) to the fire and life safety systems to unlock upon alarm as well as unlocking the doors upon loss of normal power.
CSE: Do you see any future changes/requests to the structural design of a hotel, resort, or casino building with regard to fire/life safety systems?
White: No. Most casino buildings I have dealt with are high-rise structures, and as such, their structural design is subject to a less-stringent fire-resistance requirement as a trade-off for meeting the rigorous requirements of high-rise structures. It is not typically a request by clients unless there are unique arrangements where exposed steel is desired. Performance-based structural fire engineering techniques can justify a reduction in fire resistance.
Shino: The outcome of 9/11 impacted the structural and some life safety code provisions. For supertall high-rise buildings, it introduced an additional stair, hardened elevators, and more stringent fireproofing of structural elements. Ultimately, it will most likely be a combination of building height and emergency responder access that drives requirements. Buildings continue to get higher, but emergency responder technology is not advancing at the same pace.
CSE: How have the cost and complexity of fire protection systems involved with such structures changed over the years?
Shino: While sprinkler and fire-suppression technologies continue to evolve, ultimately water-based fire protection systems remain the same. Delivering water to the fire will not change much. What has changed is the redundancy and standby water supplies. As buildings get higher and more complex, AHJs are requesting more redundancy and more standby water.
White: An important design criterion for most clients is minimal guest disruption due to false or unintended fire alarm activations. The typical solution involves careful and thoughtful zoning of fire alarm notification zones to ensure occupants who are intimate with a real fire scenario can safely evacuate, but occupants remote from a fire do not necessarily need to immediately evacuate. During a false alarm, a greatly reduced number of occupants are impacted, and this improves the guest experience. The zoning of alarms adds complexity and special coordination with fire-detection and sprinkler systems and requires fire-resistance-rated barriers between notification zones. These all add cost, making them more expensive than a system that meets the minimum code requirements.
CSE: What unique suppression systems have you specified for hotel, resort, and casino projects? Please describe.
Grove: Ceiling designs in modern casinos tend to be very intricate, resulting in cloud ceilings, numerous obstructions, and coffers that require far more sprinklers than if a smooth flat ceiling were to be provided. Therefore, instead of being able to use extended-coverage sprinklers with spacings of up to 400 sq ft, sprinkler spacing will actually be far less than 100 sq ft. With a greater number of sprinklers comes higher installation and material costs.
Where these projects have very high ceiling spaces (e.g., greater than 50 ft and up to 100 ft), new sprinkler technologies have been developed such that open-sprinkler deluge systems can be avoided. These new technologies use sprinklers with very large orifices, which create larger droplet sizes to penetrate fire plumes and quick-response operating elements that make the sprinklers operate faster. This is a benefit for designers, as the sprinkler systems are simpler with fewer valves and detection systems.
Shino: There are buildings in Las Vegas that have as many as nine fire pumps and four separate fire/water tanks or more for a complex with two high-rise towers and an interconnected podium. Pumps and their redundant partners were necessary both for the height of the towers and to distribute water throughout the 5 million-sq-ft podium. One of the challenges was sequencing the fire pumps to make sure that a pump up in the tower that starts has the water it needs when supplied from a pump in the podium that was drawing water from a break tank.
White: On one theater project, the fly loft was uniquely open such that rate-of-rise heat detection was significantly delayed. This system is normally provided to activate the proscenium water curtains, separating stages from the audience. An alternative means of activating the water curtain was developed, which included a pilot sprinkler system at the theater “grid” level. Upon activation of a pilot sprinkler, the pressure drop in the system released the proscenium water-curtain valve. Fire-plume dynamics analyses were performed to verify a reasonable activation time, which was an improvement over the rate-of-rise heat-detection method.
CSE: When working outside the US, what different types of detection, notification, or suppression systems have you specified? Outline the project and its solutions.
Shino: In many other parts of the world, there is no municipal water supply available to deliver water at the rates necessary for fire suppression. In such cases, you must have the complete water supply available for fire suppression, and many times it also requires that water be available for building systems. In many cases, they often use the same tanks for fire and building systems, so the building systems have a minimum draw level that is above the fire water level. The most unusual, but not uncommon, feature in other countries is supplying hydrants from the building’s fire water tanks. These tanks must be sized for the building’s fire-suppression systems, but the local fire service will connect to the hydrants to take water from the tanks. It seems like an odd local requirement, but it happens in many countries.
White: In Macau, they have allowed the NFPA standards of design for casino-podium fire protection systems. However, the hotel towers need to comply with local standards. In this jurisdiction, it is the British Standards or Euro Codes that apply for suppression, detection, and notification. In Macau, atria over a certain height require suppression that is open-head (deluge) and requires special detection to activate. To control the amount of fire protection water needed and stored onsite, special attention to zoning of the deluge-type system is required. The discharge zoning typically includes precise integration with ultraviolet/infrared sensor technology, air sampling, and/or beam-detection zoning.