Enclosed-space ventilation plays a pivotal role in enhancing indoor air quality (IAQ). Various regulations and guidelines determine minimum fresh air requirements, varying by the application, country, etc. The present study employs real-time indoor CO₂ measurements to calculate the actual air change rate (ACH) and models the building’s compliance with Chartered Institution of Building Services Engineers (CIBSE) guidelines to assess its impact on IAQ. The contaminant considered is the SARS-CoV-2 virus with multiple infectors, and the study calculates the virus’s transmission risk under different scenarios. Fresh air is assumed to be provided by mechanical or hybrid ventilation. The results reveal that the current building conditions are unacceptable, showing a significant gap from the recommended guideline rates. Meeting CIBSE recommendations ensures indoor air safety in terms of CO₂ concentration. However, in extreme conditions with five infectors, findings show a 14% reduction in mechanical ventilation efficacy. Among the hybrid ventilation scenarios, combining CIBSE rates with natural ventilation, with a 30% door and window opening from the class outset, proves most effective in reducing the virus’s transmission risk, with a 58–70% reduction from the building’s current condition. Furthermore, implementing supplementary measures like air cleaners resulted in an additional 28–50% reduction in transmission risk.

In today's modern world, people spend most of their time inside buildings, highlighting the importance of indoor air quality (IAQ) and providing clean air to the occupants. In this regard, a simple educational building is modeled using CONTAM-EnergyPlus co-simulation to investigate IAQ enhancement strategies and their role in the building's energy performance. Three contaminants, including CO2, PM2.5, and SARS-CoV-2, are considered to be generated from various sources. The occupants generate CO2, a source of PM2.5 is assumed in the lunchroom to represent cooking activities, and a person who sheds SARS-CoV-2 moves around the zones. The main goal of this study is to apply various pollutant mitigation methods to the model, such as increasing ventilation rate and outdoor air (OA) percentage, natural ventilation, installing filters and air cleaners, and UVGI lights. Then, their performance and impact on the defined contaminants are studied individually and in combination.In this regard, a scenario with 80% outdoor air (OA) and 100% ventilation rate has been shown to be effective in reducing all three contaminants' concentrations to acceptable levels in most zones, but this results in 50% higher energy consumption compared to the model with no outdoor air. However, to achieve a safe level of PM2.5 in the lunchroom, a combination of all the strategies presented in the (0.8OA+1Vent+NatVent+all) scenario is required. Furthermore, HEPA air cleaners are more effective in diluting contaminants in all zones than UVGI lights and MERV 13 filters. Additionally, this study has shown that HVAC systems operating with little or no outside air can increase the risk of pollutants being transmitted between adjacent zones through the ducts, making it necessary to install in-duct filters.

This study focuses on the indoor air quality (IAQ) in a higher educational building, the London College in the UK. In this regard, indoor CO₂ levels, as well as three contaminants with detrimental effects on human health: NO₂, PM_2.5, and SARS-CoV-2, are investigated. Various IAQ enhancement strategies are analyzed, including increased ventilation, background ventilation, improved airflow through opened doors, and the use of HEPA air cleaners. Results revealed that background ventilation and open doors during occupied periods reduced CO₂ concentrations to around 1000 ppm. However, the effectiveness of background ventilation was influenced by outdoor conditions, such as wind speed and direction. The most effective method for reducing PM_2.5 levels was installing an air cleaner alongside a commercial kitchen hood, resulting in a 15% greater reduction compared to background ventilation. To control the SARS-CoV-2 level, combining background ventilation or opening the doors with a 16,000 m³/h ventilation rate or using an air cleaner with baseline ventilation resulted in a basic reproductive number below 1. Overall, the research highlights the importance of background ventilation and open doors in enclosed spaces without operable windows for natural airflow. Additionally, the effectiveness of air purifiers in reducing particle and biological contaminant concentrations is demonstrated, providing valuable insights for improving IAQ in educational buildings.

In today's modern world, people spend most of their time indoors, making indoor air quality (IAQ) a critical concern, particularly in educational buildings, where densely occupied classrooms demand clean and healthy environments. This study enhances the IAQ of an existing college building in West London by aiming to reduce carbon dioxide (CO ₂ ) concentrations and SARS‐CoV‐2 infection risk, while maintaining or improving energy efficiency and thermal comfort, assessed using the predicted percentage of dissatisfied (PPD). A multi‐objective optimisation was conducted using the Non‐dominated Sorting Genetic Algorithm II (NSGA‐II). A novel approach combining optimisation with EnergyPlus and CONTAM co‐simulation was proposed to obtain the final results. Various scenarios were developed, reflecting different priorities. Energy‐saving scenarios increased PPD by 15.3% to 17.9%, while IAQ‐ and comfort‐focused scenarios raised energy consumption by 26.95% to 53.91% but maintained or improved comfort. EC45 as a mixed‐priority scenario, along with IAQ‐priority scenarios, achieved the lowest average SARS‐CoV‐2 infection risks (9.6%–10.7%). Meanwhile, other mixed‐priority (EP45‐ECP33) scenarios reduced PPD by 13.9% and maintained a 17% infection risk with only a 29% increase in energy use. This comprehensive approach demonstrates the potential for achieving healthier indoor environments in educational buildings without excessively compromising energy efficiency or occupant comfort.