The "Le Reve" water show at the Wynn Las Vegas includes a rising performer platform of fountains. Las Vegas-based JBA Consulting Engineers had to design a mechanical system that would deal with the theater's changing humidity.

While designing the HVAC systems for the new Wynn Las Vegas, the engineer, architect and mechanical contractor were confronted with rainstorms, rings of fire and water cannons.

No, this wasn't Judgment Day for Sin City.

All of it was just part of "Le Reve," the aquatic show at the Wynn, a $2.7 billion luxury hotel and casino on the Las Vegas Strip.

Le Reve was conceived by Franco Dragone, the creator of several Cirque du Soleil shows. He wanted performers to endure rain and fire indoors. However, it was up to Las Vegas-based JBA Consulting Engineers and Hansen Mechanical Contractors to make these dramatic effects possible while still ensuring the audience was comfortable.

This Dry-O-Tron is one of two 32,000-cfm Model DB-5362's that combine an additional two 11,000-cfm Model BD-5120 dehumidifiers manufactured by Dectron Inc.

Special effects

Opened in April 2005, the Wynn has more than 2,000 guest rooms, an 111,000-square-foot casino, meeting spaces, an on-site golf course, spa and more.

It is also home to "Le Reve," an acrobatic water show. Meaning "The Dream" in French, it has performers "flying" through the air and swimming through a 1.1 million-gallon performance pool. All of this is set in a 32,000-square-foot theater-in-the round complex, which can seat over 2,000 people.

"This was one of my most technical projects," said Brad Geinzer, principal mechanical engineer with JBA Consulting Engineers. The firm has had a hand in designing the HVAC systems for other high-tech Las Vegas theatrical venues such as the Caesars Palace Coliseum and multiple Cirque du Soleil showrooms.

The HVAC design challenge for "Le Reve" began with the main 8,200-square-foot, 1.1 million-gallon pool used in the show. While the pool itself presented somewhat of a humidity nightmare, the show also includes an 80-foot-high rainstorm, a "boiling effect" that sends bubbles and water roaring out of the pool, and an ample assortment of water cannons and other aquatic effects, not to mention supplemental staging pools.

The Wynn Hotel hosts the "Le Reve" aquatic show. The $2.7 billion hotel on the Las Vegas strip offers over 2,000 guest rooms and 111,000-square-foot casino.

The challenge

All totaled, Geinzer had to figure out how to control the 950 pounds of moisture produced by the show each hour. He decided to use two 32,000-cfm Model DB-5362 and two 11,000-cfm DB-5120 Dry-O-Tron dehumidifiers manufactured by Montreal-based Dectron Internationale Inc., which serve the aquatic staging areas beneath the seats and the general theater dehumidification, heating and cooling systems.

More conventional pool designs, such as a community or water-park indoor pools, typically have constant statistics on water usage to help size equipment properly. Geinzer didn't have that luxury.

"We knew the concept of the effects they were going to use during our HVAC design phase, but we had no idea how long or how much of the effect would be part of the show," Geinzer recalled. "Basically, they want to leave open the opportunity for creativity, so they designed the theatrical performance as they went along and adjustments in the show continue even today."

In most natatorium designs, air and water temperatures typically have just a two-degree difference to minimize evaporation. The Le Reve pool water is 86ºF; however, the air above the pool is 105ºF to keep the wet performers warmer.

The air is supplied from ductwork and diffusers in a 10-inch-wide "pony wall" that also serves as a low-rise buffer between spectators and performers. Three 3,200-cfm York air handlers supply the pool surface-air heating.

"The pony wall serves as an unobtrusive air-delivery system for the performers and it also helps prevent this warmer performance-area air from entering the seating area," said Geinzer.

This huge vapor-pressure difference required difficult evaporation calculations by JBA. The company was assisted by Matt Miceli, sales engineer and manufacturer's representative for Engineered Equipment & Systems Co. in Las Vegas.

Acrobats in "Le Reve" soar above the 1.1 million-gallon pool in the 32,000-square-foot theater-in-the-round.

In the seats

Meanwhile, the audience is kept comfortable with air supplied by the seating area's foundation, which acts as a plenum. Air is distributed from specially designed theater-seat diffusers by H. Krantz, a German manufacturer. Although it's used in a variety of applications, the H. Krantz system is ideal for theaters and concert halls, officials say, because it's designed to disperse air with such low velocities that the air-volume noise is inaudible to the audience.

The seating area has three separate plenums with eight control zones each and temperatures controlled by sensors working with the hotel's direct-digital-control building-automation system from Invensys Controls America.

JBA, which also provided life safety, mechanical, electrical and low-voltage systems for the hotel, took advantage of Las Vegas' inherently dry climate to lessen the dehumidification loads of the theater, according to Geinzer.

The DDC presets, programmed by JBA and Invensys representative Yamas Control Systems Southwest Inc., are used often during moments in the show requiring different temperature, airflow and relative humidity set points.

For example, one part of the performance requires momentary backstage positive pressurization to create fog in the main theater. Making calibrations such as this easier was the fact that all the air handlers, dehumidifiers and exhaust fans have Toshiba America variable-frequency drives controlled by the DDC system.

"Working around all these possible show conditions without disrupting audience comfort made the project very challenging," said Geinzer.

One thing JBA has learned from its work on HVAC designs at other Las Vegas water shows is that many stagehands work above the performance with props and lighting, and must be provided with separate temperature and humidity levels for their comfort.

The JBA-installed system is also energy efficient. Dry-O-Trons employ a heat-recovery process to heat the pool's water. Plate heat exchangers by Alfa Laval provide primary pool water heating with backup heat from the facility's central plant when required.

The ceiling of the theater has four exhaust fans made by Greenheck. Two fans provide conventional exhaust functions and keep the theater at a negative pressure to keep its air out of the rest of the hotel. Two other exhaust fans are used to control smoke from the production.

Aside from humidity, a ring of fire with huge center flames also has an unpredictable effect on airflow throughout the theater. The system had to be designed to remove combustion byproducts during the flame effects. Dozens of life-safety sensors for smoke, heat and flame detection are mounted throughout the seating and performance area and work with the digital-control system.

This article and its images were provided by Dectron Internationale.