This article discusses about a requirement that aims to protect occupants from dangerous smoke concentrations and keep escape routes clear in a building that houses a restaurant in Zurich, Switzerland. It has to be ventilated with windows in the roof that open automatically in case of fire. For a substantial building, the difference between automated venting for one percent and two percent of a roof surface can represent tens of thousands of dollars. The AFC Air Flow Consulting hired by the restaurant uses computational fluid dynamics and visualization software to improve construction and product design before too much time or money is committed. The company has provided solutions for flow problems ranging from cold downdraft along facades to droplet dispersion. A field of growing interest for AFC is industrial engineering. The company optimizes the airflow to accommodate various parameters in technical parts, such as the airflow in a medical inhaler for homogeneous distribution of droplets, or the air intake device of a car ventilation system for water separation.

## Article

A flow study computed in CFX-Tascflow and visualized in EnSight argues that an alternative emergency ventilation plan will enable a building to meet a city's code.

A building that houses a restaurant in Zurich, Switzerland, has to be ventilated with windows in the roof that open automatically in case of fire. The requirement aims to protect occupants from dangerous smoke concentrations and keep escape routes clear. It is also expensive.

For a substantial building, the difference between automated venting for one percent and two percent of a roof surface can represent tens of thousands of dollars.

Architects at Ortner & Ortner of Vienna, Austria, facedjust such a situation when the firm was hired to remodel Zurich’s old Schifibauhalle, or ship-building hall. The hall turned out more than 100 ships between 1836 and 1913, but had stood empty for several years. Then a project was hatched to transform the building into a series of theaters, restaurants, and bars while maintaining the outer structure as a testament to its history.

To investigate the issue of fire-emergency ventilation, the architects turned to specialists at Switzerland’s technical university, the Federal Institute of Technology, in Zurich. The institute, often called by its German initials, ETH, brought in one of its spin-off companies, AFC Air Flow Consulting.

Vienna architects Ortner & Ortner turned Zurich’s Schiffbauhalle—empty for years—into an entertainment center.

AFC uses computational fluid dynamics and visualization software to improve construction and product design before too much time or money is committed. The company has provided solutions for flow problems ranging from cold downdraft along facades to droplet dispersion.

The planners turned to Alois Schaelin, founder and CEO of AFC Air Flow Consulting, and Peter Rosemann of ETH to help them reach a solution that would save time and money while still adhering to the strict fire codes.

Using information on smoke properties from fire and safety literature, Schaelin and Rosemann developed a computational model of the building using CFD software from CFX-Tascflow in Otterfing, Germany. The resulting models contained up to one million cells. They solved the transport equations for energy, momentum, turbulent quantities, and an additional scalar for smoke to create a time-dependent data field that allowed for transient animations.

## The Smoke Clears

The inside room and a number of small interior buildings and compartments were combined with part of the outdoor space to allow for free natural airflow where openings were designed. Openings located in the roof sheds and doors were tested to determine fresh air supply. The calculation results, representing 10 minutes of real time, also showed a smoke distribution scenario for a fire within a restaurant located in a smaller building that is part of the hall complex.

This article teas prepared by staff writers in collaboration with outside contributors.

Schaelin and Rosemann estimated the height of the smoke, as well as transient temperature and contamination distributions.

The CFD calculations were then exported to EnSight, which is visualization software from CEI in Apex, N.C. The purpose of the EnSight visualizations was to help the researchers in the early planning phases foresee the correct measures to take against hazardous situations.

Schaelin and Rosemann discovered that only one percent of the roof needed to be openable if the ventilation strategy included automatically opening doors to keep smoke moving up and out.

Schaelin and Rosemann presented their animations to convince fire officials that only one percent of the röof needed to open to provide proper ventilation and secure escape paths in case of a fire. Not having to increase roof openings saved $60,000 for the$12 million restoration project.

## One for the Books

Under a separate project involving ventilation, AFC created a scenario for a new library building integrated into an existing structure. AFC visualized how two different fresh air sources—one from the basement and another using the building’s entryway doors—disperse smoke. AFC concluded that the doorways provided better ventilation. The architect then redesigned the entrance hall to make better use of the ventilation through the doors.

A field of growing interest for AFC is industrial engineering. The company optimizes the airflow to accommodate various parameters in technical parts, such as the airflow in a medical inhaler for homogeneous distribution of droplets, or the air intake device of a car ventilation system for water separation.

AFC uses EnLiten, animation software also from CEI, to present airflow findings for buildings or medical inhalers. According to Schaelin, “Architects and planners have more confidence in the CFD calculation when they can see results in animations and interact with them.”