A Passive Solution for Smoke Exfiltration for Resorts World, Las Vegas

Posted on April 26, 2021

 

Wind and temperature differentials can cause unexpected results for tall buildings located in hot and/or cold climates. If not properly accounted for issues such as frequent jamming of lift doors and uncomfortable internal wind conditions in lobbies and main entrances can occur. These issues were anticipated by the project team behind the Resorts World, Las Vegas project.

Fusing three premium brands – Hilton Hotels & Resorts, LXR Hotels & Resorts and Conrad Hotels & Resorts – Resorts World, Las Vegas is targeting to open in the Summer of 2021.

Designed by Steelman Partners, this $4.3 billion resort will feature a 110,000ft² casino floor, 3,500 guest rooms and luxury suites and a 5,000-capacity theatre, plus much more. The project team included DeSimone Consulting Engineers, Enclos and Corte Cladding Consultants, and Windtech were thrilled to be an integral member of the team.

With such a high-end development, ensuring a reliable,efficient, and comfortable indoor and outdoor environment was an essential target for Resorts World, who have been rolling out developments all over the world for many years.

(Background image courtesy of rwlasvegas.com – Inset image courtesy of Windtech Consultants)

Windtech was invited to conduct a wide-ranging scope of wind tunnel testing for the design and optimisation of the structural and cladding systems, and also looked at various environmental effects such as how to solve air quality issues using passive stack effect.

The stack effect or reverse stack effect are caused when there is a temperature differential between the internal conditioned areas of the building and the outside air. When the internal air is warmer than the external conditions, air is drawn in at the lower levels and rises within the building, this is the stack effect. The reverse stack effect occurs when the inside of the building is cooler than then external air and air flows out of the lower levels of the building. Vertical air flows within the building are also driven by the external façade pressurisation of the building.

These two effects are commonly experienced at the ground level entrances or lift doors for high-rise structures during the cooler months of the year for the stack effect and during the warmer months of the year for the reverse stack effect. Additionally, flows may occur at ground level entrances or lift doors driven only by the wind driven external pressurisation of the building under any temperature conditions. For developments that are not particularly tall and located in a temperate climate, it can been assumed that any internal air flows driven by temperature only will be negligible and flows driven by thermal forces only not considered.

Fig 1. Ground Floor modelled flow rates and typical data outputted for various aspects of stack effect phenomenon throughout the building envelope for the summer season. (Note: image above is not of Resorts World)

Aaron Lefcovitch, a Director at Windtech’s Singapore office comments “It is important to be able to measure the impacts of stack effect, as uncontrolled air movement within a building tends to hamper the performance of lift and access doors, mechanical and fire systems, and can even cause undesirable wind conditions at key entrance locations around the building.However, in this exciting example the client was proactive in anticipating the potential issue of smoke propagating from the casino floor to other areas of the building, namely the hotel lobby. Traditionally these issues are solved by designing expensive mechanical systems, however we were able to help the client design a passive system which utilised the power of nature and the stack effect”.

Fig 2. Ground Level Smoke Concentrations

Windtech undertook a detailed study that combined pressure data from the wind tunnel, computational modelling of smoke dispersion on the casino gaming floor and a numerical analysis of stack effect which identified the existence of smoke infiltration into the hotel lobby areas during a calm day in winter. It was concluded that this effect could be mitigated by adjusting the amount of supply and return in the HVAC systems – a simple solution to complex problem.

Windtech was pleased to work with such an esteemed group of consultants for a client that supported a value engineering approach to solve a complex problem.

Another interesting study undertaken for this project include the assessment of the impact of building accelerations for occupant comfort as well as lift operation. Other studies include wind loads and tip deflections under design wind loads and cladding pressures on the façade as well as the LED systems that are to cover the facade of the development (see inset image above) as well as an extensive wind environment study.

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