A total of 8 mechanically ventilated residential buildings and 8 naturally ventilated residential buildings were selected to analyze the pollution characteristics of indoor VOCs under different ventilation modes in the severe cold area of northeast China. On typical meteorological days in each season, VOCs were detected on site, and ventilation modes were investigated by long-term online monitoring. The test results showed that the TVOC (total volatile organic compounds) concentrations varied greatly in different seasons or different functional rooms, and the TVOC concentration was the highest in winter, with a value of 0.994 mg/m³. The kitchen was the place with the most serious VOC pollution, and the TVOC concentration could reach 1.403 mg/m³. Benzene series and methylsiloxane had the highest detection rates, but the detected concentrations were low, and the average concentrations were 0.025 mg/m³ and 0.013 mg/m³ respectively. Among the VOC types with a detection rate greater than 50%, the average proportions of aldehydes, alkanes, and benzene series were 18.7%, 15.39%, and 14.38%, respectively. And their mass ratios were also high, which were 14.90%, 30.85%, and 15.70%, respectively. The annual daily average ventilation duration of mechanically ventilated residential buildings was 7.84 h longer than that of naturally ventilated residential buildings. The median TVOC concentrations of mechanically ventilated residential buildings and naturally ventilated residential buildings were 0.621 mg/m³ and 0.707 mg/m³, respectively. The fresh air system was applicable in the severe cold area of northeast China.

The negative impact of indoor formaldehyde pollution has become a growing interest, especially in severe cold areas, since most residential buildings do not have enough ventilation and people are unwilling to open windows. In order to explore the status and the influencing factors of indoor formaldehyde pollution in severe cold areas and predict the formaldehyde concentrations in these areas, a study of 60 residential buildings in Liaoning, China, was carried out using the method of phenol reagent spectrophotometry. While testing the formaldehyde concentration, the infiltration air change rate of the room was also tested using CO₂ as a tracer gas. The correlation between formaldehyde concentration and its influencing factors was analyzed by SPSS software. Multiple linear regression equations were established for the linear regression analysis. The measured data were used to assess the formaldehyde cancer risk of residents in Liaoning. The test results showed that the most serious rates of average formaldehyde pollution occurred in summer with a concentration of 0.097 mg/m³, and the bedroom was the room most seriously polluted by formaldehyde in autumn with a concentration of 0.104 mg/m³. According to the correlation analysis, the formaldehyde concentration was significantly correlated with the indoor temperature, years of decoration, and the infiltration ventilation rate. The linear regression equation for predicting the formaldehyde concentration was established. According to the risk assessment of the test results, residents in Liaoning are already at risk of cancer caused by formaldehyde.

The transformation of family structure in China has resulted in a surge in the demand for elderly care, as seniors are always frail and unable to tend to their own needs. Consequently, it is imperative that nursing homes provide a secure indoor environment. To this end, sophisticated instruments or national standard methods had been employed to measure indoor environmental parameters, while objective questionnaire interviews targeting the elderly had been conducted during the winter of 2021. The findings revealed a temperature differential of 3.5°C between north- and south-facing rooms. An average indoor concentration of formaldehyde (HCHO) of 0.025 mg/m ³ with PM _2.5 and CO ₂ concentrations remaining within acceptable limits. Furthermore, senior citizens expressed greater concern regarding indoor temperature, humidity levels, sunlight exposure and ventilation quality. Based on the research findings, computational fluid dynamics tools were employed to simulate and optimize ventilation in an existing nursing home. Natural ventilation and simple mechanical ventilation were proposed as practical approaches to fulfil the health and comfort requirements of elderly residents. The outcomes offer programmatic and data support for comprehending indoor environments in nursing homes located in severely cold regions, as well as for retrofitting indoor ventilation systems in economically viable existing nursing facilities.

This paper takes a graduate workshop in shenyang as the research object, and uses Airpak software to conduct numerical simulation analysis on the air distribution and thermal comfort of the fan coil side air supply mode in winter. The measured air supply temperature is 25°C, air supply speed in the x direction for 0.8m / s, 1.5m / s and 2.3m / s three gears, from east to west up to back air supply 3mode. With the increase of air supply speed, the temperature of the working area gradually increases, and the wind speed increases. PMV index and PPD index were used to evaluate the indoor comfort under the three air supply speeds. The air sup 3ply speeds of 1.5m/s and 2.3m/s can meet the requirements of indoor comfort. According to the distribution of personnel, 18 measuring points were set for measurement. The comparison between the simulation results and the measured results showed a consistent trend, which verified the feasibility and accuracy of Airpak for indoor thermal environment comfort analysis.

Residents' window-opening behavior is the most basic method to obtain fresh air and improve the indoor environment, and is also an important factor affecting building energy consumption. The behavior of opening and closing windows of urban residents will be different due to regional differences. However, there are less of the thorough enough research on the time and seasonal habit of residents’ window-opening behavior in Liaoning. This paper investigated the window-opening behavior and its influencing factors of 28 typical urban households in natural ventilation and mechanical ventilation houses in Liaoning province by questionnaire survey and on-site testing. The opening and closing behavior of residents’ windows were continuously monitored online for one year by using magnetic sensors of XIAOMI brand. The long-term monitoring results showed that the window-opening behavior of residents in Liaoning has strong seasonality. In summer, the window-opening time is relatively longer, and often more than 24 hours. What’s more, most local residents have the habit of opening windows for ventilation when they get up in the morning, even in the cold winter. The understanding of the window-opening behavior of residents in this area can provide strong support for architectural design or renovation strategy.