Building Airflow Modeling for Design of Pressurization · PDF fileBuilding Airflow Modeling...
Transcript of Building Airflow Modeling for Design of Pressurization · PDF fileBuilding Airflow Modeling...
Building Airflow Modeling for Design of Pressurization Systems High Rise Hotel • New York, NY
www.haifire.com www.haifire.com
30-story high rise hotel
New construction
Fully sprinklered
Two (2) pressurized fire-rated stairwells
Four (4) pressurized elevator hoistways
www.haifire.com www.haifire.com
Smoke Management Objectives
Meet code requirements and design objectives for multiple smoke control systems
• Stairwell pressurization within 0.15 – 0.35 in H2O
• Elevator pressurization within 0.10 – 0.25 in H2O
• Corridor and Public Space Smoke Exhaust
• Eight (8) air change per hour exhaust
• Six (6) air change per hour supply
www.haifire.com www.haifire.com
Typical Floor Plan (Most Floors)
Elevators Stairs
www.haifire.com www.haifire.com
Open Floor Plan (Floors 5 and 25)
Elevators Stairs
www.haifire.com www.haifire.com
Approach
Perform computer modeling to determine minimum fan capacities required for satisfactory pressurization under a range of conditions.
• CONTAM Building Airflow model, developed at NIST
www.haifire.com www.haifire.com
Smoke Control Modeling Inputs
Stair and Elevator Pressurization (Supply)
Corridor Purge (Exhaust)
www.haifire.com www.haifire.com
Challenge
Elevator and stair pressurization create competing forces.
Typical Floor
Open Layout Floor
Differences in airflow resistance on the typical floors compared to the open layout floors provides an engineering challenge.
www.haifire.com www.haifire.com
Challenge
Pressurized air follows the path of least resistance.
Relatively high architectural leakage on the open layout floors (Floors 5 and 25) results in high differential pressures across the stair and elevator doors on these floors.
www.haifire.com www.haifire.com
Solution
Developed a “hybrid” approach:
• Air capacities supplied to the stair and elevator shafts are reduced to provide a minimum differential pressure of 0.05 in. W.G. on all floors (minimum allowable pressure difference across smoke barriers per IBC).
• The capacity of the corridor exhaust is increased to provide higher differential pressures on the fire floor (meeting local code requirements).
The proposed smoke control system was verified under a range of architectural leakage assumptions and a range of outside temperatures.
www.haifire.com www.haifire.com
Solution
www.haifire.com www.haifire.com
Results
Modeling showed satisfactory pressurization would not be achievable on all floors due to the differences in architectural leakage on the open layout floors (Floors 5 and 25).
Developed and tested a solution involving a hybrid approach using different design pressures for the non-fire and fire floors
The solution resulted in:
• Minimal mechanical and architectural changes to the building.
• Reduced fan sizes needed for stair and elevator pressurization.
• Eliminating unsafe door opening force conditions.
• Meeting local code requirements on the fire floor while maintaining the minimum pressure differential for smoke barriers on the non-fire floors.
www.haifire.com
Michael J. Ferreira, PE Principal
410-737-8677 x284 [email protected]
For More Information Contact: