Analysis on the Function of Elevator shaft Vents

In the bellow conversation with ChatGPT, I made the following judgment. I'd love to hear your thoughts on my judgment!

1. NFPA 92 appears to be based on the immediate opening of elevator vents in the event of a fire.

2. The only real-world application of elevator vents appears to be on rooftops. 

   Elevator shaft smoke and heat extraction system | CWS

3. In the event of a fire in the upper floors of a building in the summer, the elevator shaft on the roof will open (the neutral zone will be at the top of the building), and if the elevator shaft is not pressurized, and the temperature of the smoke leaking from the fire chamber is not much higher than the temperature inside the building, it can play a role in propagating smoke throughout the lower floors of the building. 

However, this does not appear to have been discussed in depth in the U.S. industry. 

Therefore, without empirical verification that this is not a problem, it is unlikely that open vents on unpressurized elevator rooftops should be permitted in the event of a fire.  

Conversation with ChatGPT

Q(Me) : Followings are noted in the NFPA 92, 2021.  

"4.7 Elevator pressurization systems. Where elevator pressurization is provided, elevator hoistways shall be pressurized to maintain a minimum positive pressure in accordance with 4.4.2. The minimum pressure shall be maintained with the elevator car at the recall floor and elevator doors and the hoistway vents open."

Please tell me more the expression "The minimum pressure shall be maintained with the elevator car at the recall floor and elevator doors and the hoistway vents open." in the above.

A(ChatGPT) : In the context of NFPA 92, 2021, the expression "The minimum pressure shall be maintained with the elevator car at the recall floor and elevator doors and the hoistway vents open" refers to the specific conditions under which the minimum positive pressure should be ensured within an elevator hoistway.

Here's a breakdown of the different elements mentioned in the expression:

Elevator Car at the Recall Floor: The recall floor is a designated floor or landing where the elevator is programmed to automatically return and remain in the event of a fire alarm or other emergency. To maintain the minimum positive pressure, the pressure within the elevator hoistway should be measured with the elevator car positioned at this recall floor.

Elevator Doors Open: The elevator doors are required to be open during the pressure measurement process. This ensures that the air pressure within the hoistway is properly measured in a state where there is unrestricted airflow between the hoistway and the elevator shaft.

Hoistway Vents Open: Hoistway vents are openings or ducts that allow air to flow in and out of the elevator hoistway. These vents are typically equipped with dampers that can open or close as needed. To maintain the minimum positive pressure, the hoistway vents should be open, allowing for the necessary airflow within the hoistway.

By maintaining the minimum positive pressure under these specific conditions (elevator car at the recall floor, elevator doors open, and hoistway vents open), the elevator pressurization system ensures that smoke or fire gases are prevented from entering the hoistway, thereby providing a safer environment for occupants using the elevators or emergency personnel who might access the hoistway during an emergency situation.

Q(Me) : "Elevator doors open" in the above means Elevatro car door? Or, All doors between Elevator shaft and lobies?

A(ChatGPT) : In the context of the expression "The minimum pressure shall be maintained with the elevator car at the recall floor and elevator doors and the hoistway vents open," the term "elevator doors" refers to the doors of the elevator car itself, not the doors between the elevator shaft and lobbies.

When it mentions that the elevator doors should be open, it means that the doors of the elevator car should be in an open position. This is to ensure that there is unobstructed airflow between the elevator car and the elevator hoistway during the pressure measurement process.

The purpose of having the elevator car doors open is to allow the air pressure within the hoistway to be accurately measured and maintained. By keeping the elevator car doors open, the pressure within the hoistway can be balanced with the surrounding environment, preventing the intrusion of smoke or fire gases in the event of an emergency.

It's worth noting that the specific requirements for elevator doors may vary depending on local building codes and regulations, so it's important to consult the relevant standards applicable in your specific jurisdiction.

Q(Me) : Regarding "Hoistway Vents Open" in the above, where and how many are the hoistway vents installed generally in US ?

A(ChatGPT) : The installation and number of hoistway vents in elevator systems can vary depending on the specific building codes, design considerations, and local regulations. However, I can provide you with some general information about hoistway vents in the United States.

Hoistway vents are typically installed in elevator shafts at various locations to allow for the controlled flow of air. The purpose of these vents is to facilitate ventilation and pressure equalization within the elevator hoistway, particularly in the event of a fire or smoke-related incident.

The number and placement of hoistway vents can depend on factors such as the size of the elevator system, the height of the building, the number of elevator shafts, and the specific requirements of the local building codes. Hoistway vents are typically located at multiple levels throughout the elevator shaft to promote effective airflow.

The exact specifications for hoistway vents, including their size, location, and operation, are typically outlined in the applicable building codes and standards, such as the National Fire Protection Association (NFPA) standards, including NFPA 92 for smoke control systems.

It's important to note that specific details regarding the installation and number of hoistway vents should be determined in accordance with the local building codes and regulations, as well as consulting with design professionals and authorities having jurisdiction in your area.

Q(Me) : Generally, are the 'Hoistway Vents'  installed between Elevator shaft wall and ambient?  

A(ChatGPT) : Yes, generally, hoistway vents are installed between the elevator shaft wall and the ambient environment. They serve as openings or ducts that allow for the controlled flow of air into and out of the elevator hoistway.

Hoistway vents are designed to facilitate ventilation and pressure equalization within the elevator shaft. They help maintain a safe and controlled environment in the event of a fire or smoke-related incident. By allowing for the exchange of air, hoistway vents help prevent the buildup of smoke or fire gases in the elevator hoistway.

The specific location and design of hoistway vents can vary depending on factors such as the building's design, local building codes, and the specific requirements of the elevator system. Typically, hoistway vents are strategically placed at multiple levels throughout the elevator shaft to ensure effective airflow and pressure control.

The installation of hoistway vents between the elevator shaft wall and the ambient environment helps ensure that the ventilation system operates efficiently and helps maintain a safe environment for elevator passengers and emergency personnel.

Again, it's important to consult the relevant building codes, standards, and local regulations to determine the specific requirements for hoistway vents in a particular jurisdiction.

Q(Me) : If elevator shaft is installed in the center area, not in the edge, the vents are installed with ducts to connect ambient?

A(ChatGPT) : If the elevator shaft is located in the center area of a building rather than at the edge, the installation of hoistway vents may require ducts to connect the vents to the ambient environment. The specific design and installation requirements for the hoistway vents and associated ducts will depend on various factors, including building design, local codes, and system specifications.

In situations where the elevator shaft is not located near an exterior wall or an easily accessible outdoor area, connecting ducts may be necessary to allow the hoistway vents to reach the ambient environment. These ducts can be used to channel air to and from the elevator shaft, providing the necessary airflow and pressure equalization.

The design and installation of these ducts should comply with relevant building codes, fire protection standards, and ventilation requirements. It's crucial to work with qualified professionals, including mechanical engineers and architects, to ensure that the hoistway vents and associated ductwork are designed and installed properly to meet the specific needs of the building and comply with applicable regulations.

Q(Me) : can you tell me the postings showing the reference figures for vent mentioned above?

A(ChatGPT) : As an AI text-based model, I don't have direct access to external sources or the ability to display images or reference figures. However, I can provide you with a general description of the vent types typically used in elevator hoistways.

Hoistway vents can come in various designs, but two common types are louvered vents and grilles:

Louvered Vents: These are typically rectangular-shaped openings with adjustable blades, known as louvers, that allow for controlled airflow. Louvered vents are designed to prevent the entry of rain, debris, or other external elements while still facilitating the exchange of air between the hoistway and the ambient environment.

Grilles: Grilles are typically perforated metal plates or screens that are installed over openings in the elevator shaft wall. They provide a level of protection against debris and prevent accidental contact with moving elevator components, while still allowing for the passage of air.

The specific dimensions, placement, and configurations of hoistway vents may vary based on factors such as the building's design, local codes, and the requirements of the elevator system. These details can be found in the relevant building codes, such as the NFPA 92 standard for smoke control systems, or other elevator industry standards.

To access the reference figures or detailed illustrations related to hoistway vents, I would recommend referring to the specific codes, standards, or engineering resources that provide comprehensive guidance on elevator ventilation and fire safety. These resources can provide visual representations and specifications for the design and installation of hoistway vents in different scenarios.

Q(Me) : Are these elevator shaft vents used for stack effect elimination?

A(ChatGPT) : Yes, elevator shaft vents can be used to mitigate the effects of stack effect in buildings. Stack effect refers to the natural phenomenon where differences in temperature and pressure between the bottom and top of a building create vertical airflow within the building.

In the context of elevator shafts, stack effect can result in air movement within the shaft, which can impact the overall ventilation and smoke control system. By incorporating properly designed vents in the elevator shaft, the stack effect can be controlled and minimized.

The placement and configuration of hoistway vents can help balance the pressure and airflow within the elevator shaft, reducing the potential for stack effect to disrupt ventilation systems. By allowing controlled airflow through the vents, pressure differentials and air movement caused by stack effect can be mitigated.

However, it's important to note that while elevator shaft vents can help address stack effect to some extent, they are just one component of a comprehensive ventilation and smoke control system in a building. Other factors, such as the design of stairwells, shaft pressurization systems, and HVAC systems, also play a role in managing stack effect and maintaining proper airflow throughout the building.

Building codes and standards, such as NFPA 92, provide guidelines for designing and installing ventilation systems in elevator shafts to address both smoke control and stack effect considerations. Consulting these codes and working with qualified professionals is essential to ensure that the ventilation system effectively addresses stack effect and meets the specific requirements of your building.

Q(Me) : To eliminate stack effect, the vents shall be acurately controlled to protect unintended adverse effect. If so, the vents shall be controlled by firefighters not by automatic? 

A(ChatGPT) : You are correct that to effectively manage stack effect and prevent unintended adverse effects, the control of elevator shaft vents may need to be managed appropriately. The specific control mechanisms for elevator shaft vents can vary depending on the building design, fire protection systems, and local codes and regulations.

In many cases, elevator shaft vents are designed to operate automatically in response to specific conditions, such as fire alarms or smoke detection systems. These automatic controls ensure that the vents activate promptly and appropriately during an emergency, allowing for the release of smoke, heat, and gases from the elevator shaft.

However, it's worth noting that elevator shaft vents can also be designed with manual control capabilities. This can allow firefighters or emergency personnel to take control of the vents during firefighting or rescue operations. Manual control can be beneficial in certain situations where the ventilation strategy needs to be tailored to the specific needs of the emergency response.

The precise control requirements for elevator shaft vents should be determined in accordance with the local building codes, fire protection standards, and regulations governing your specific jurisdiction. These regulations typically outline the specific control methods and considerations for elevator shaft vents, ensuring that they are appropriately managed to address both fire safety and stack effect concerns.

To ensure compliance and the safe operation of elevator shaft vents, it is crucial to work with fire protection professionals, building code authorities, and other relevant stakeholders who can provide guidance specific to your building's circumstances.

Q(Me) : If the vents are controlled by automatic generally, they are controlled differently according to seasons(winter, summer, spring, fall)?

A(ChatGPT) : The control of elevator shaft vents in relation to different seasons (winter, summer, spring, fall) can vary depending on the specific design of the building's ventilation system and the requirements set forth by local codes and regulations. Different strategies may be employed to optimize ventilation and airflow based on seasonal conditions.

In general, the control of elevator shaft vents can be influenced by factors such as outdoor temperature, humidity levels, and the need to maintain appropriate indoor air quality. Here are some common approaches to ventilation control in different seasons:

Winter: During the winter season, the control of elevator shaft vents may prioritize minimizing heat loss from the building. Vents may be designed to operate in a manner that reduces air exchange with the colder outdoor environment, helping to maintain indoor temperatures and conserve energy.

Summer: In the summer season, the focus of ventilation control may be on heat dissipation and managing indoor temperatures. Vents can be configured to promote the exchange of hot air from the elevator shaft with cooler outdoor air, facilitating heat removal and enhancing occupant comfort.

Spring and Fall: In transitional seasons, the control of elevator shaft vents may aim to strike a balance between temperature regulation and energy efficiency. The vents can be adjusted to accommodate varying outdoor conditions, optimizing airflow and indoor climate based on the specific needs of the building.

The specific control strategies employed for elevator shaft vents can also depend on the presence of other mechanical systems, such as HVAC systems, that are responsible for overall climate control in the building. Integration and coordination between these systems may be necessary to achieve desired ventilation outcomes throughout the year.

It's important to note that the specific control sequences and strategies for elevator shaft vents in different seasons should be determined based on the building's design, local codes, energy efficiency requirements, and the input of relevant professionals, including mechanical engineers and HVAC specialists.

Q(Me) : If the vents are generally controlled by automatically in the fire condition, they are controlled differently according to seasons(winter, summer, spring, fall)?

A(ChatGPT) : In the case of elevator shaft vents during a fire condition, their control is primarily focused on smoke control and the safe evacuation of occupants rather than seasonal considerations. During a fire, the primary objective is to prevent the spread of smoke and fire within the building, ensuring the safety of occupants and facilitating the work of firefighters.

In a fire situation, elevator shaft vents are typically controlled automatically based on the activation of fire detection systems, such as smoke detectors or heat sensors. When these systems detect the presence of smoke or fire, they initiate the operation of the ventilation system, including the activation of the elevator shaft vents.

The control logic for elevator shaft vents in a fire condition is typically designed to create a pressure differential, guiding the flow of smoke away from occupied areas and towards exhaust points or smoke control systems. The specific control sequences and strategies may vary depending on the building's fire protection design, the size and configuration of the elevator shaft, and local fire codes and regulations.

Seasonal considerations, such as outdoor temperature or climate control, are generally not the primary factors influencing the control of elevator shaft vents during a fire. The primary focus is on the immediate safety of occupants and the suppression and containment of the fire and smoke.

It's important to consult local fire codes, building regulations, and work with fire protection professionals and authorities having jurisdiction to ensure that the control of elevator shaft vents during a fire complies with the specific requirements and regulations applicable to your jurisdiction.

Q(Me) : If the vents are generally controlled by automatically in the fire condition, I think they are controlled differently according to seasons(winter, summer, spring, fall). Because the stack effect makes different  pressure in the elevator shaft according to seasons.

A(ChatGPT) : You are correct that stack effect can vary in different seasons, which can result in different pressure differentials within the elevator shaft. These seasonal variations in stack effect can influence the control of elevator shaft vents during a fire condition.

In situations where the stack effect significantly affects the pressure differentials within the building, the control of elevator shaft vents may need to be adjusted to account for these variations. The goal is to maintain the desired pressure differentials to prevent the migration of smoke and fire within the building and ensure effective smoke control.

The control sequences for elevator shaft vents during a fire can be designed to account for seasonal variations in stack effect. For example:

Winter: During the winter season, when the temperature difference between the interior and exterior of the building is more significant, stack effect can be more pronounced. In this case, the control of elevator shaft vents may prioritize maintaining a higher pressure in the lower floors to prevent the infiltration of cold outdoor air and reduce heat loss from the building.

Summer: In the summer season, when the temperature difference between the interior and exterior is reduced or reversed, stack effect may be less pronounced. The control of elevator shaft vents during a fire in the summer may aim to balance pressure differentials to prevent the migration of smoke and maintain a safe environment for evacuation and firefighting operations.

The specific control strategies and adjustments for elevator shaft vents to address seasonal variations in stack effect can depend on factors such as the building design, HVAC systems, and local fire codes and regulations. Consulting with fire protection professionals, engineers, and authorities having jurisdiction will help determine the appropriate control sequences for elevator shaft vents during a fire, considering the specific seasonal considerations and stack effect variations in your building.

Q(Me) : The concepts you mentioned above has been adapted actually in the building?

A(ChatGPT) : The consideration of seasonal variations in stack effect and the adjustment of elevator shaft vent control accordingly are design considerations that can be implemented in building projects. However, the specific implementation and application of these concepts may vary depending on factors such as building design, local building codes, and the preferences of the building owner or developer.

In some cases, building designers and fire protection engineers may incorporate strategies to address stack effect variations and seasonal considerations in the design of ventilation systems, including the control of elevator shaft vents. These strategies can aim to optimize smoke control, maintain pressure differentials, and enhance occupant safety during a fire.

It's important to note that the implementation of these strategies can vary from building to building. Factors such as the building's size, occupancy type, HVAC system design, and local fire codes and regulations all play a role in determining the specific approaches taken for elevator shaft vent control.

Ultimately, the application of seasonal adjustments in elevator shaft vent control during a fire condition depends on the specific project, its design objectives, and the expertise and decisions of the project team, including architects, engineers, fire safety consultants, and local authorities.

To ensure accurate and appropriate implementation, it is crucial to engage with qualified professionals who have expertise in fire protection engineering and are familiar with local building codes and regulations. They can provide guidance tailored to your specific building project and ensure compliance with relevant standards and requirements.

Q(Me) : You don't know whether the concepts you mentioned above has been adapted in the building?

A(ChatGPT) : As an AI language model, I don't have access to real-time data or specific information about individual building projects. I can provide general knowledge and guidelines based on industry standards and practices, but I cannot provide specific information on whether or how these concepts have been implemented in specific buildings.

The implementation of concepts such as considering seasonal variations in stack effect and adjusting elevator shaft vent control accordingly can vary from building to building. It ultimately depends on the design choices, engineering considerations, and compliance with local building codes and regulations for each specific project.

To determine whether these concepts have been adapted in a particular building, it would be necessary to consult the building's design plans, specifications, and documentation, or reach out to the project architects, engineers, or building owners. They would have the most accurate and up-to-date information on how these concepts were incorporated into the building's ventilation system and elevator shaft vent control.

It's important to work with qualified professionals and consult the relevant local authorities and building codes for specific project requirements and compliance. They can provide the most accurate information on the implementation of these concepts in a particular building.

* Back to Main Procedures : General COMTAM Simulation Procedure for Pressure differential system(Mainly High-rise building) (contamsmulationlab.blogspot.com)