This study utilized a questionnaire survey to collect data from 265 residents in Changchun, encompassing building characteristics, ventilation frequency and overall satisfaction with the indoor environment. Statistical analysis revealed significant disparities in ventilation frequency and satisfaction with indoor temperature. The survey results indicate that the primary mode of indoor air exchange amongst Changchun residents is window ventilation, accounting for 93%. Field tracking was conducted to measure indoor air concentrations of volatile organic compounds (VOCs) in residential buildings during winter and summer seasons. The study revealed a significant increase in the average indoor/outdoor (I/O) ratio of the targeted 25 VOC concentrations in winter, rising from 10.8 to 17.7. The findings underscore indoor sources as predominant contributors to the measured VOCs. Temperature, humidity and room functions are the main factors affecting VOC concentration. Higher temperatures and increased relative humidity both contributed to elevated indoor VOC levels. This study recommended the opening of more windows during high temperature and high humidity in summer, to maintain good indoor air quality and effectively age the emission of VOCs from furniture. This study contributes to the enhancement of the database on indoor air quality and effective ventilation strategies in cold regions for safeguarding public health.

The outbreak of coronavirus disease 2019 (COVID-19) has had a significant impact on human life. Hybrid ventilated hospitals have emerged as multi-zone sites, necessitating ventilation strategies to mitigate viral concentration. This paper integrates multi-zone infiltration and exfiltration (MIX) model of natural ventilation, spatial flow impact factor (SFIF) model and pollutant concentration model to analyze the inter-zonal impact. Results indicate that elevated outdoor temperature corresponds to an increased influence of rooms on corridors. Adopting mechanical ventilation in rooms diminishes the influence of room pollutants on corridors but exerts minimal impact on other rooms. Mechanical air supply reduces the interaction between corridors, and the reduction is most significant when wind direction is the same as stairwell orientation. The corridors do not affect the upstream rooms when the source is in the corridor. When wind speed is below a threshold, mechanical air supply is recommended; for wind speed reaching this threshold, mechanical air exhaust volumes should be adjusted regarding the wind speed. The study reveals that corridor and room window openings exert disparate effects on corridor concentration under mechanical air supply conditions. All the findings offer valuable insights for selecting ventilation strategies in hybrid ventilated hospitals, with the aim of mitigating COVID-19 transmission.

This study investigated the effect of exhaust air volumes on the performance of range hoods at different angles in residential kitchens in removing grease pollutants, during the pollutant emission stage (whilst cooking) and the pollutant attenuation stage (after cooking). Experiments were conducted, and introduced indexes such as capture efficiency, exposure rate, attenuation rate, power and multi-indicator analysis were used to analyze the performance of the range hood with different exhaust air volumes and angles. The experimental results showed the capture efficiency was increased with an increase in exhaust air volume whilst cooking. Considering the energy consumption of the range hood and noise, the exhaust air volume of the range hood should be set at 600 m3/h to 800 m3/h. In the pollutant attenuation stage, the attenuation rate K of PM2.5 mass concentration was increased with the incremental increase in the exhaust air volume. When cooking was finished, grease pollutants remained in the kitchen. If the range hood continued to be turned on and a large exhaust air volume was set, the concentration of indoor grease pollutants could be quickly reduced to below the standard value. Our findings can provide a reference for the airflow regulation of residential kitchen range hoods.

Conventional air purifiers are low effective in inactivating airborne bacteria and may cause secondary contamination by releasing endotoxins. In this study, a novel air purifier was developed and used in a static chamber, which used slightly acidic electrolysed water (SAEW) solutions as the circulating disinfectant spray medium that automatically renewed every 30 min. During the 30-minute operation, the air and solution samples were collected to measure the bacteria and endotoxin concentration by using a culturable-based method and a limulus amoebocyte lysate assay kit, respectively. The pH and endotoxin of the circulating solution were gradually increased, and the available chlorine concentration (ACC, from 87 to 50 mg/L) was decreased. Although airborne bacteria were reduced significantly, the levels of airborne endotoxins at the inlet and outlet of the purifier remained constant. Moreover, a validation experiment revealed that SAEW, with ACC of 20, 60 and 100 mg/L, cannot inactivate standard endotoxin solutions. In the experimental chamber, the airborne bacteria level (1142 CFU/m3) was significantly lower compared to the control chamber (3325 CFU/m3), with no significant difference in airborne endotoxin levels between the chambers. Our results showed that the SAEW spray air purifier could effectively remove airborne bacteria without increasing airborne endotoxin levels within a 30-minute operational period.

In a fire, stairways are the primary avenues for building evacuation. Previous studies focused on investigating evacuation flow through evacuation drills in a high-rise office building to assess the accuracy of evacuation scenarios and compared them with evacuation dynamics. However, the effectiveness of evacuation drills in estimating many scenarios is limited by actual drills. The evacuation simulations present a promising approach to objectively evaluating evacuation scenarios. This study verifies whether evacuation simulations can faithfully replicate actual evacuation flow and effectively predict suitable evacuation scenarios or potentially involve parameter calibration. Through a comprehensive comparison analysis, this study scrutinized the reliability of evacuation simulations and calibrated the simulation parameters. The analysis revealed that factors, including adjustments to the door width, personal space considerations for occupants in both conflict and normal situations and variations in staircase structure configuration, can significantly influence the evacuation flow within staircases. Manipulating these parameters in simulations would enable a more precise replication of evacuation flow within staircases, thereby enhancing the simulation’s accuracy in target evacuation scenarios. The findings of this research have underscored the significance of employing advanced simulation techniques to model evacuation dynamics accurately, facilitating a robust framework for devising effective emergency evacuation strategies in high-rise office buildings.

Current building techniques in developing countries have become extremely critical. The net-zero energy concept has emerged as an essential strategy for minimising energy consumption and greenhouse gas emissions. However, its implementation, particularly in developing countries, remains a critical challenge. The purpose of this work is to assess the feasibility of achieving a net-zero energy building by combining energy-efficient design practices and renewable energy systems under the climatic conditions of the Republic of Congo. To achieve the stipulated objectives, DesignBuilder software was utilised for building modelling, energy load assessment and multiobjective optimisation of building energy efficiency measures, and the multicriteria energy optimisation was carried out using the HOMER tool. The optimisation results showed that the implementation of energy efficiency measures resulted in 39.15% energy savings, 43.45% thermal load savings and 55.68% discomfort hours reduction. Furthermore, the renewable energy system can provide 100% of the building’s energy load and a total savings of 3341.84 kgCO2eq/year. The system’s levelised cost of energy was estimated at 0.256 $/kWh, with a net present cost of $20,231, while the overall life cycle cost was calculated at 188.91 $/m2.

As a place for the maintenance of high-speed trains, the current ventilation system in the train depot cannot meet comfort requirements according to the feedback from the inspection department. The poor thermal environment could seriously affect the physical health and work efficiency of staff. This study provides some basic data and design methods for improving the thermal environment in high-speed railway depots. Field studies were conducted in five different high-speed railway depots in hot summer regions of China, including the form and the operation of the ventilation system, the thermal and humid environment and the characteristics of the heat sources. According to the survey results, the maximum temperature in the depot can reach 41.2°C in summer. There is a clear vertical temperature stratification in the afternoon of the depot, and the maximum temperature difference between three working platforms can reach more than 4°C. The cooling effect of ventilation systems in depot was investigated and compared. The recommended ventilation mode is natural ventilation system + bottom mechanical air supply system + ceiling fan system, and it is recommended to combine the west window louvers with external sun shading to achieve the best cooling effect in high-speed railway depot.

The air distributor is the end component of the ventilation system, and its performance directly determines the comfortable and pleasant feeling of the residence. A perforated plate can be added to the air distributor to convert dynamic pressure into static pressure first and then distribute the air flow, which provides better self-adjustment compared with the embedded guide vane structure. However, the perforated plate can lead to a contradiction between head loss, noise and distribution uniformity. To reconcile this problem, a novel V-shape configuration of the perforated plate was put forward in this study. The internal flow and aeroacoustic properties of different types of perforated plates were systematically studied, and a full-scale test platform was built to verify the flow characteristics. The effects of hole size and installation position of the perforated plate on the uniform distribution of air flow were analyzed by the parametric analysis method. Then, the sound pressure level of the optimized perforated plate air distributor was further analyzed. The results show that, with the optimized perforated plate structure, the uniform flow performance was improved by about 30% and the overall sound pressure level was reduced by up to 12 dB.

Optimising ventilation strategy for an indoor environment necessitates systematically evaluating the influence of a diverse combination of physical and operational parameters in the design space. This study proposes a methodology that couples an evolutionary algorithm (genetic algorithm) with an evaluation mechanism (computational fluid dynamics) to determine the optimal ventilation strategy for an inpatient ward. The traditional approach would exhaustively simulate numerous scenarios to identify the optimal combination of parameters meeting the design objective. The proposed methodology would iteratively evaluate diverse design solutions with fewer CFD simulations than the traditional approach. The results of design space exploration suggest that design parameters, namely, location of the infected patient; air change rate; flow rate through local exhaust grille; and number, location and size of supply air diffuser and local air exhaust grille, are critical in minimising the risk of cross-infection caused through contact transmission in a ward.