Conference Agenda

Far-UVC (222 nm) technology offers a promising solution for effective air disinfection in indoor environments, significantly enhancing the mitigation of airborne pathogens without posing substantial risks to human health. In this work, we present an exact analytical solution for evaluating the efficiency of air disinfection in indoor spaces equipped with 222 nm UV technology, employing a multi-zonal model for the approximation of pathogen concentration dynamics. The multi-zonal approach divides the indoor space into distinct regions, each characterized by different levels of UV irradiation and ventilation, allowing for a more nuanced analysis of disinfection performance.

It is important to understand how well-mixed a room is when it is continuously ventilated. This becomes complicated when the interaction of two modes of pathogen removal (i.e., dilution by ventilation and inactivation by UV) is governed by this mixing. To address this, the model incorporates the stream function-vorticity formulation of the Navier-Stokes equations in elliptical coordinates to accurately simulate the flow fields, vorticity distribution, and transport of airborne pathogens. By solving the governing partial differential equations, we achieve a detailed representation of airflow patterns, which is crucial for predicting the movement of pathogen-laden aerosols. The stream function-vorticity method effectively reduces computational complexity by eliminating the pressure term, while elliptical coordinates accurately represent the complex geometry typically encountered in indoor environments.

In addition to UV germicidal intervention, the model integrates ventilation dynamics, natural pathogen decay, and deposition processes. The interaction between irradiated and non-irradiated zones within the room is explicitly modeled, providing a detailed quantification of air exchange rates and their implications for disinfection efficiency. This study's findings provide valuable insights into the design, optimization, and deployment of efficient, human-safe UV disinfection systems in a wide range of indoor settings, ultimately contributing to improved indoor air quality and reduced transmission of airborne diseases.

The Future Homes Standard to be implemented in the UK by 2025, provides guidelines for new homes to be "zero-carbon ready" by enhancing energy efficiency, incorporating low-carbon heating and high fabric efficiency. These steps may unintentionally impact on indoor air quality and increase occupants’ exposure to harmful pollutants.

At the University of Salford’s state-of-the-art Energy House 2.0 research facility, the effectiveness and energy efficiency of ventilation and air purification systems to enhance indoor air quality were assessed within a Future Home built by Bellway. Energy House 2.0 comprises two environmental chambers, each accommodating two detached houses, designed to recreate a wide range of weather scenarios under controlled conditions.

Experiments included controlled injections of particulate matter (PM), gases and real-world cooking activities to simulate pollutant generation, comparing various ventilation strategies such as DMEV, MVHR, and commercial air purification purifiers under well-defined reproducible control scenarios. High-resolution online research instrumentation, including mass spectrometry and particle sizing, allowed for detailed chemical fingerprinting of gases and analysis of PM behaviour , and a suite of distributed sensors enabled interrogation of pollutant dispersion within the home.

Our findings indicate significant reductions in indoor CO₂, PM, and Volatile Organic Compound (VOC) concentrations by the tested ventilation systems, which could be integrated into future homes in the UK. During controlled releases of traceable pollutants, MVHR and DMEV modes consistently proved effective in reducing pollutant concentrations across all rooms. Similarly, air purification units achieve PM reductions of up to 90-95%, effectively limiting pollutant dispersion. While hydrocarbons and less-oxygenated VOCs were often substantially reduced, reductions for highly oxygenated species were less pronounced.

This unique test house, with comprehensive suite of air pollution measurements, enables the development of novel calculations linking energy consumption with indoor air quality improvements, supporting cost-benefit analyses to quantifying health and comfort gains alongside energy savings or costs.

In the Clean Air for Everyone (CLAIRE) program, experimental particle measurements were conducted to analyze aerosol/particle distribution behavior across various ventilation systems under realistic, operational conditions in primary schools. In total, 19 different ventilation settings were tested in eight different classrooms, with measurements taken both before and after ventilation improvements in each classroom. Before the intervention six of the eight classrooms were ventilated through natural ventilation, after the intervention all classrooms were equipped with a mechanical ventilation system. In two classrooms, the effect of an air cleaner on particle exposure was also assessed.

For each ventilation setting, measurements were taken from six positions using particle counters, with two representative emission locations per case. A measurement cycle consists of determining the baseline of the particle concentration (5 minutes), emission of particles (10 minutes), switching off emission (15 min) and cleaning the room to baseline concentration. Outcome parameters are the 100-fold increase time, the 100-fold recovery time, tdelay and the local air change rate.

Results showed non-homogeneous particle distribution (limited mixing) before interventions, with natural ventilation being mainly influenced by external conditions (i.e. wind). The reduction in particle exposure takes a long time, however, varies significantly between different classrooms and within a classroom. After ventilation interventions, most classrooms exhibited lower particle concentrations and faster reduction of concentration after particle emissions stopped. Enhanced ventilation also led to a more homogeneous particle distribution (better mixing and dilution). The air cleaners used in this study had a longer 100-fold recovery time compared to replacing the ventilation system at similar ventilation rates. These findings provide insights into particle distribution patterns in classrooms under different ventilation set-ups, aiding strategies for reducing airborne particle exposure.

The construction industry is a major source of airborne pollutants. In interior renovations, the focus is usually on protecting building occupants by containing the work zone, rather than on workers within the workspace. This often exposes workers to high levels of airborne contaminants without adequate air quality control measures in their immediate environment. In response, this study investigates the impact of portable air scrubbers on indoor air quality (IAQ) in a mock-up renovation within a university construction lab. This study examines the device’s effectiveness in reducing common construction pollutants, such as particulate matter (PM₂.₅) and volatile organic compounds (VOCs) that are often elevated during construction and renovation work. To simulate the challenges of IAQ in a typical indoor construction workspace, the experimental setup comprised a small, enclosed wood structure within a construction lab, where dust, off-gassing, and limited ventilation could create poor air quality conditions. Findings indicate that air scrubbers and effective IAQ management strategies are essential for maintaining safe air quality in enclosed renovation spaces. This study emphasizes the value of IAQ monitoring for evaluating equipment effectiveness and promoting healthier indoor environments in construction spaces used by both students and workers. Future studies could explore the prolonged effects of portable air scrubber use on IAQ in diverse construction situations and evaluate their efficacy against a broader range of pollutants and under different environmental conditions. Last, this study offers practical guidance for construction managers and educational institutions seeking to improve the IAQ in controlled, enclosed workspaces.