University students are self-directed learners who dedicate considerable time to studying in study places. Research on indoor environmental quality (IEQ) highlights the adverse effects of prolonged indoor exposure to environmental stressors, including noise. Acoustical quality can significantly influence students’ health and comfort. To evaluate the acoustical quality of study places, three groups of indicators can be considered: occupant-related, dose-related, and building-related indicators. Given that students have different acoustical and psychosocial preferences for study places, it is crucial to consider occupant-related indicators. However, existing acoustical guidelines for study places and educational buildings primarily focus on dose-related and building-related indicators, while occupant-related indicators have been overlooked. Therefore, the main research question of this dissertation was posed:
How to assess the acoustical quality of study places?
This question was answered through several research methods. First, a literature review identified indicators and methods used to study students’ acoustical preferences and needs. Then, ‘MyStudyPlace’ questionnaire was completed by university students who were clustered based on their IEQ and psychosocial preferences, resulting in nine profiles. Subsequently, students were re-clustered based on acoustical and selected psychosocial preferences, resulting in five profiles. To further explore these profiles, 23 home study places were visited, incorporating interviews, building inspections, and sound pressure level measurements. After that, 15 of these students participated in sound exposure lab experiments, which involved bodily responses, audiometric tests, and perceptual assessments. Furthermore, an indoor soundscape approach using semi-structured interviews with the 23 students examined their sound environment experiences of their home study places. This dissertation offers future research a set of suggested methods and indicators to assess the acoustical quality of study places.

In response to the WHO and UN’s call to ensure children’s right to breathe “clean” air and the challenges posed by the COVID-19 pandemic on maintaining healthy indoor air quality (IAQ), this PhD research explores ventilation and air cleaning strategies to control the spread of infectious respiratory particles (IRPs) in school classrooms.

The study follows four key steps: (1) a literature review bridging school ventilation regimes, IRP transmission, and advanced ventilation systems; (2) a field study to evaluate real-world ventilation and thermal conditions during the pandemic; (3) an experimental investigation of performance of mobile air cleaners (MACs) followed by an in-situ validation; and (4) a combined experimental and computational study to assess personalized air cleaners (PACs) as localized exhaust for IRP removal.
Findings reveal that most classrooms rely on natural ventilation, often failing to meet IAQ standards, especially when fully occupied. With windows and doors open, ventilation rates remained inconsistent, and thermal conditions were unsatisfactory. Hence, more controllable ventilation and air cleaning approaches are needed. MACs, when appropriately selected and positioned, offer effective protection against long-range IRP transmission at room scale, while PACs are effective at mitigating localized, short-range IRP exposure, improving IAQ at an individual level.

This research offers a comprehensive set of solutions for IRP control in classrooms, with actionable insights for a variety of stakeholders. It advocates for a shift from comfort-based to health-centered paradigms. Future research should explore hybrid systems, optimize designs, and validate interventions through real-world infection risk assessments to create healthier, more resilient classrooms.

A housing shortage has been building up in the Netherlands in the last 30 years. Decreasing the housing shortage takes time, while people need a place to live now. Temporarily transforming vacant buildings into housing could reduce this need by providing the housing market with time to catch up. Can different user perspectives be included in housing design so all residents can easily make their home? A review of literature from housing studies, indoor environmental quality, architectural design and environmental psychology, for students, starters on the housing market and refugees accepted for permanent residency, indicated that using meanings of home could benefit housing design. Six factors were identified using a questionnaire that was developed to identify differences in meanings of home and what activities people engaged in, linked to indoor environmental preferences they had for those activities. Qualitative methods were used to better understand what people do to make a home. Three groups of activities were identified that reflect how home is a place built with meanings, through the use of objects, decorations, and the presence of other people. The results of a workshop with professionals indicated that meanings of home can be organised on three axes and that activities operate on different time frames (continuous, long-term, and short-term, respectively). This means that small actions, too, can contribute to creating a home, though which specific actions help someone and which do not, depend on the individual. The results can be used for housing design when architects and psychologists work together.

The airborne transmission of SARS-CoV-2 in educational buildings has raised concerns during the current COVID-19 pandemic. In this study, a portable fog generator system was designed and assembled to visualise the airflow pattern of exhaled droplets in a classroom. The system consists of five components: medium, fog generator, buffer, pump, and manikin head. The medium was made of a combination of glycol and demineralised water, which produced a fog composed of droplets mimicking to some extent human breath. The fog was produced with the fog generator and passed through a pipe into the buffer for build-up. After accumulation, the fog is pumped through another pipe and is exhaled out of the mouth of the manikin. The experiments were conducted in a simulated classroom. The lights of the room were dimmed and six lasers were used to make the fog more visible. Four different ventilation regimes were examined: no ventilation, natural ventilation (open windows and door), mixing ventilation (600 m3/h), and a combination of natural + mixing ventilation. The experiments were recorded with a camera and analysed to determine the horizontal distance of the path taken by the fog and to measure the time it remained visible after exhalation from the mouth. During the experiments, it could be observed with the naked eye that the glycol droplets travel much further and linger in the air for longer than what is captured in the recordings. Furthermore, not all the droplets were visible with the camera, especially the smaller ones of a few micrometres in diameter. The recordings showed that at the natural ventilation regime the droplets travelled the furthest distance (1.8 metres). This wind coming through the door pushed the drops further into the room. The combination of natural + mixing ventilation regime had the highest indoor air velocity, causing the droplets to reach the shortest distance (0.5 metres). In conclusion, the type of ventilation, classroom layout, and exhalation location play an important role in determining the airflow pattern, as they affect how long and how far the glycol droplets travel. Applying any type of ventilation is critical in transmission control and reduces the possibility of aerosol accumulation in the classroom as smaller droplets can linger in the air for many hours until they settle on a surface.

It is well-known that the indoor environmental quality (IEQ) at schools affects the health, comfort and performance of school children. Considering the need for a more effective way to improve both the IEQ in primary school classrooms and children’s satisfaction, along with the positive potential of individual control, this thesis aimed to propose a new way - individual control - to improve the IEQ in classrooms of primary schools and to increase children’s satisfaction in the Netherlands. First the main IEQ problem in classrooms as well as IEQ perceptions and preferences of the school children were identified through literature and field studies. The outcome showed that noise was the main IEQ problem in classrooms of Dutch primary schools, children could be clustered in according to their IEQ perceptions and preferences, and the reported IEQ-improving actions of the teachers could not effectively improve the IEQ for each child. As a follow-up, lab studies were performed in the SenseLab to explore the effect of background sound on children’s sound perception and performance. Together with the outcome of the field studies, results suggested that individual control is a better way to improve IEQ in classrooms. Therefore, to address the main problem – noise - in classrooms, an individually controlled noisereducing device was designed, prototyped and tested with school children in the SenseLab. The results obtained from the simulations, measurements, and children’s feedback on the prototype of the device, demonstrated the feasibility of such devices in classrooms at primary schools.

A design for a garment factory in Bandung (Indonesia). The focus is on the indoor environment: lighting, indoor air quality, thermal comfort and acoustics.