Concurrent supply and exhaust ventilation (CSEV) has been developed to effectively exhaust heat and contamination from the kitchen. The objective of this research was to investigate the performance variation of this system with respect to air flow rates. CSEV system can block the contaminated air from entering the inner space by supplying fresh air horizontally in the ceilings towards the hood where the overflowed contaminated gas tends to diffuse to inner part of the room. The system captures contaminated air in an area near the ceiling and this captured air is then exhausted through the ceiling outlet. For quantitative evaluation, heat and gas capture efficiencies were defined and calculated. Experiments were conducted to compute heat and gas capture efficiencies based on the temperature and SF₆ concentration data that were measured at the exhaust locations. To find optimum operation conditions for a CSEV system, numerical analysis was carried out. The numerical results were in good agreement with the experimental values. Maximum differences between the two methods are 17% for hood system and 10% for CSEV. Both heat and gas capture efficiencies would increase as exhaust flow rate of the hood increases. However, the optimum supply flow rate of ceiling nozzle was found to be 100 m³/h for maximum efficiency. This optimum flow rate condition would improve removing heat and contamination from the kitchen for better indoor air quality.

Owing to the recent increase in the number of warning reports and alerts on the dangers of fine dusts, there has been an increasing concern over fine dusts among citizens. In spaces with poor ventilation, the occupants are forced to open the window to initiate natural ventilation via the direct introduction of the outside air; however, this may pose a serious challenge if the external fine-dust concentration is high. The lack of natural ventilation increases the indoor carbon dioxide (CO₂) concentration, thus necessitating the installation of mechanical ventilation systems. This study analyzed the frequency of the application of mechanical ventilation systems in the Multi-purpose activity space of elementary schools, which are spaces where children require a higher indoor air quality than adults owing to the rapid increase in the CO₂ concentration of the Multi-purpose activity space during activities. In addition, the architectural and equipment factors of the Multi-purpose activity spaces of nine elementary schools were characterized. The results revealed that five out of the nine elementary schools installed mechanical ventilation systems, whereas the remaining four schools installed jet air turnover systems. The indoor air quality of the Multi-purpose activity space of D elementary school, which had the minimum facility volume among the schools investigated in this study (564.2 m³), with up to 32 participants for each activity, was investigated. The results revealed that the ultrafine-dust (PM2.5) concentration of the facility was as high as 4.75 µg/m³ at a height of 1.2 m, and the CO₂ concentration was as high as 3183 ppm. The results of the analysis of three elementary schools with different volumes were compared and analyzed using CONTAM simulation. This study determined the required volume per occupant and the optimum number of occupants for a given volume and presented guidelines for the optimum number of occupants, activities, and volume to reduce the high concentration of pollutants in the analyzed Multi-purpose activity space. The guideline proposed in this study is aimed at maintaining the CO₂ concentration of the Multi-purpose activity space below 1000 ppm, as prescribed by the Indoor Air Quality Control in Public-Use Facilities, Etc. Act in South Korea.

To save electricity consumption in university buildings, we measured and compared the amount of electricity use with and without motion detection sensors and room management systems in underground parking lots, lecture rooms, and dormitories of a university building. The underground parking lots and lecture rooms were measured as sensors were applied and then removed during the semester. University classes are held weekly, so it can be assumed that the number of cars and people’s entering and using conditions are the same. In the university’s underground parking lots, a daily electricity savings of 39.5 Wh/(m² day) of lights was achieved, with a savings rate of 77.6%. In the lecture rooms, these values were 25.0 Wh/(m² day) and 32.4%, respectively. Savings in the use of air conditioning were 55.0 Wh/(m² day), with a savings rate of 27.9%. Dormitories use electrical energy for lighting, heating, and socket outlets. As a reference group, 120 rooms were selected and the room management system was applied to 10 samples. For dormitories, daily electricity savings of 142.4 Wh/(m² day) were achieved, with a savings rate of 28.2%. Thus, this study demonstrated that applying motion detection sensors and room management systems saved significant electrical energy in university underground parking lots, lecture rooms, and dormitories.

Ventilation is becoming increasingly important to improve indoor air quality and prevent the spread of COVID-19. This study analyzed the indoor air quality of office spaces, where occupants remain for extended periods, among multi-use facilities with an increasing need for ventilation system application. A “tool for office space CO₂ prediction and indoor air quality improvement recommendation” was developed. The research method was divided into four steps. Step 1: Analysis of indoor air quality characteristics in office spaces was carried out with a questionnaire survey and indoor air quality experiment. Based on the CO₂ concentration, which was found to be a problem in the indoor air quality experiment in the office space, Step 2: CO₂ concentration prediction tool for office spaces, which requires inputs of regional and spatial factors and architectural and equipment elements, was developed. In Step 3: Development and verification of prediction tool considering economic feasibility, the cost of energy recovery ventilation systems based on the invoices of the energy recovery ventilation manufacturers was analyzed. In Step 4: Energy recovery ventilation proposal and indoor CO₂ forecast, Office Space B, which can accommodate up to 15 people, was derived as an example of the proposed tool. As a result of the prediction, the optimal air volume of the energy recovery ventilation was determined according to the “office CO₂ prediction and indoor air quality improvement recommendations”. This study introduced simple tools, which can be used by non-experts, that are capable of showing changes in indoor air quality, CO₂ concentration and cost according to activities.

To delay fossil energy depletion and implement the Paris Climate Change Accord, the South Korean government is attempting to reduce greenhouse gas emissions with the establishment of the 2030 Roadmap. The insulation performance of external walls is being continuously enhanced in the architectural domain. However, Korea’s policy and construction market focuses only on the heat resistance of buildings’ external walls to enhance the insulation performance, leading to an increased thickness of the insulation materials. In this study, the relationship between the surface reflectivity and insulation thickness of external walls was examined to formulate an effective insulation strategy for buildings in Korea. Office buildings of 12 regions in the Korean Peninsula were considered. The dynamic energy simulation program EnergyPlus was used to perform the heating and cooling load analyses. The present worth method was adopted to perform the economic analysis. The analysis of the cooling and heating loads indicated that a change occurred not only in terms of the latitude but also between the Eastern and Western regions. The energy consumption could be reduced by increasing the reflectivity in the Southern region and lowering the reflectivity in the Northern region, based on the total load. In addition, a higher latitude corresponded to a higher energy saving effect owing to the increased insulation thickness. In the case of Jeju Island and Busan, regions with a relatively large cooling load and small heating load, the total load is little affected by insulation thickness at high reflectivity. If the external skin was considered to have the optimal reflectivity, the regions for optimal insulation thickness could be divided into three categories: north, central and south.

This paper presents a study of a 98.1 kW-PV system facing south at an inclined angle of 15º on the roof of a university building in Seoul, South Korea (latitude 37.63° N and longitude 127.1° E). The system performance was analyzed for 2 years from Sep. 2015 to Aug. 2017. The average electrical power output was 0.59 kWh/(m²·day) with a 16.9% average annual efficiency for the 1st year which further decreased to 0.58 kWh/(m²·day) with average annual efficiency of 17.6% in the 2nd year. The annual irradiance was 3.50 kWh/(m²·day) for the 1st year and 3.31 kWh/(m²·day) for the 2nd year with a total annual output generation of 105.4 MWh and 103.5 MWh, respectively. Average daily power generations were 2.93 and 2.89 kWh/(kWp·day) for 2 years, respectively, with an annual performance ratio range of 80 ~ 90%. Predicted module temperatures show a good correlation with measured temperatures. Predicted and measured output values show a strong correlation. During the 1st year at a maximum module temperature of 60ºC, power output loss was found to be 13.3%, while in the 2nd year at a maximum module temperature of 57ºC, the power output loss observed was 12.2%.