Natural ventilation in a building is an effective way to achieve acceptable indoor air quality. Ventilation dilutes contaminants such as bioeffluents generated by occupants, substances emitted from building materials, and the water vapor generated by occupants’ activities. In a building that requires heating and cooling, adequate ventilation is crucial to minimize energy consumption while maintaining healthy indoor air quality. However, measuring the actual magnitude of the natural ventilation rate, including infiltration through the building envelope and airflow through the building openings, is not always feasible. Although international and national standards suggested the required ventilation rates to maintain acceptable indoor air quality in buildings, they did not offer action plans to achieve or evaluate those design ventilation rates in buildings in use. In this study, the occupant-generated carbon dioxide (CO2) tracer gas decay method was applied to estimate the ventilation rates in an office room in Seoul, South Korea, from summer to winter. Using the method, real-time ventilation rates can be calculated by monitoring indoor and outdoor CO2 concentrations without injecting a tracer gas. For natural ventilation in the test room, 145 mm-diameter circular openings on the fixed glass were used. As a result, first, the indoor CO2 concentrations were used as an indicator to evaluate how much the indoor air quality deteriorated when all the windows were closed in an occupied office room compared to the international standards for indoor air quality. Moreover, we found out that the estimated ventilation rates varied depending on various environmental conditions, even with the same openings for natural ventilation. Considering the indoor and outdoor temperature differences and outdoor wind speeds as the main factors influencing the ventilation rates, we analyzed how they affected the ventilation rates in the different seasons of South Korea. When the wind speeds were calm, less than 2 m/s, the temperature difference played as a factor that influenced the estimated ventilation rates. On the other hand, when the temperature differences were low, less than 3 °C, the wind speed was the primary factor. This study raises awareness about the risk of poor indoor air quality in office rooms that could lead to health problems or unpleasant working environments. This study presents an example of estimating the ventilation rates in an existing building. By using the presented method, the ventilation rate in an existing building can be simply estimated while using the building as usual, and appropriate ventilation strategies for the building can be determined to maintain the desired indoor air quality.@en

People in cities are often exposed to complex mixtures of sounds, some originating from nature along with some created by human activities like traffic noise, sounds of industrial machinery, or music. This research aimed to study how the acoustic environment of a university campus is perceived by people. The procedures for soundscape data collection and analysis were based on the ISO 12913 series. 30 volunteers divided into four groups participated in a “soundwalk” at the campus of the architecture school in Detmold, Germany, filling out questionnaires while sound measurements and recordings were being taken. After the soundwalk, the data from the questionnaires, sound measurements, recordings, pictures and videos were analyzed. The findings suggest that people’s perception of sound is susceptible to the context, as participants seemed to shift their preference according to the ongoing activities that drew attention, such as a construction site, sounds from children playing, music and groups of people. The results provide new evidence and insights about the acoustic environment and the soundscape of the university campus and can inform stakeholders to improve environmental quality.@en

Façades cover a significant amount of surfaces in cities and are in constant interaction with the acoustic environment. Noise pollution is one of the most concerning burdens for public health and wellbeing; however, façade acoustic performance is generally not considered in outdoor spaces, in contrast to indoor spaces. This study presents a systematic literature review examining 40 peer-reviewed papers regarding the effects of façades on the urban acoustic environment and the soundscape. Façades affect sound pressure levels and reverberation time in urban spaces and can affect people’s perception of the acoustic environment. The effects are classified into three groups: Effects of façades on the urban acoustic environment, including sound-reflecting, sound-absorbing and sound-producing effects; Effects of façades on the urban soundscape, including auditory and non-auditory effects; Effects of the context on the acoustic environment around façades, including boundary effects and atmospheric effects. @en