Shopping mall ventilation duration is a critical factor in ensuring indoor air quality and the comfort of occupants. The recommended ventilation duration for shopping malls in the United States typically ranges from 30 to 60 minutes per hour. This duration is based on the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) standards, which aim to maintain acceptable indoor air quality levels while minimizing energy consumption.

The ventilation duration in shopping malls is influenced by several factors, including the size of the mall, the number of occupants, and the type of activities taking place within. According to a study published in the Journal of Building Performance Simulation, a ventilation rate of 20 to 30 air changes per hour (ACH) is generally sufficient to maintain acceptable indoor air quality in shopping malls. This translates to a ventilation duration of approximately 30 to 60 minutes per hour.

The reason for this recommended ventilation duration is to ensure that indoor air pollutants, such as carbon dioxide (CO2), volatile organic compounds (VOCs), and particulate matter, are effectively removed from the indoor environment. These pollutants can originate from various sources, including human respiration, building materials, and activities such as cooking or smoking. By maintaining a consistent ventilation rate, shopping malls can reduce the risk of indoor air quality issues that can lead to discomfort, health problems, and even building-related illnesses.

ASHRAE Standard 62.1-2019, "Ventilation for Acceptable Indoor Air Quality," provides guidelines for ventilation rates in commercial buildings, including shopping malls. The standard suggests that a ventilation rate of 20 to 30 ACH is appropriate for spaces with high occupancy levels or where activities generate significant amounts of pollutants. This range ensures that the indoor air quality remains within acceptable limits while also considering energy efficiency.

For example, a study published in the International Journal of Environmental Research and Public Health found that maintaining a ventilation rate of 30 ACH in a shopping mall resulted in significantly lower levels of CO2 and VOCs compared to a ventilation rate of 15 ACH. This demonstrates the importance of adequate ventilation in maintaining a healthy indoor environment.

In conclusion, the recommended ventilation duration for shopping malls in the United States is approximately 30 to 60 minutes per hour, based on ASHRAE standards. This duration is designed to ensure acceptable indoor air quality while balancing energy efficiency. By adhering to these guidelines, shopping malls can create a comfortable and safe environment for their occupants.