Cities & Health

Traffic is the primary source of air pollutants in urban areas, posing significant health risks to humans, animals, and plants. Airborne pollutants such as particulate matter (PM) and chemically active gases such as NO and NO2 can travel long distances through wind transport, causing pollution even far from the original source. Integrated modeling analysis is needed to better understand and address this issue.

Vegetation elements such as trees, hedges, and green facades play a critical role in controlling pollutant dispersion. However, assessing the complex interactions between green elements, airflow, turbulence, and pollutant deposition cannot be done simply. The ENVI-met software enables the estimation of the benefits of complex nature-based solutions by integrating pollutant dispersion modeling with high-resolution vegetation modeling.

Air pollution is not just an outdoor problem. Opening windows or using air conditioning can bring outdoor pollutants indoors. The quality of the air you get when you open your window depends on the microscale wind patterns around the building. The ENVI-met software analyzes wind flow and pollutant transport for each facade segment of a building with a resolution down to one meter.

The urban heat island phenomenon involves varying degrees of heat accumulation within neighborhoods and entire districts. To fully understand the thermal behavior of a city at the block or neighborhood level, it is critical to perform dynamic simulations that account for all causal elements. These elements include surface and wall temperatures, wind flow patterns, vegetation transpiration, and soil moisture. By integrating all of these factors into the simulation process, ENVI-met software provides a multi-perspective analysis of the urban system, encompassing building physics, vegetation health, and human thermal comfort.

Urban neighborhoods are a patchwork of microclimates. The variety of materials, buildings, and vegetation create a patchwork of very different microclimates within close proximity. Shaded backyards and urban parks can provide cool pockets and recreational areas even in hot summer conditions. To understand and analyze the impact of redesign and mitigation strategies, a continuous simulation of at least 24 hours must be run to capture all the different heating and cooling effects in an urban area.

Human perception of temperature is influenced by meteorological factors such as wind, solar and thermal radiation, air temperature, and humidity. To gain insight into how humans experience thermal conditions, biometeorological models are used. For example, ENVI-met’s BIO-met module calculates the Physiological Equivalent Temperature (PET), which relates outdoor conditions to an imagined indoor environment. In addition, the Dynamic Thermal Comfort tool simulates and evaluates the thermal comfort experienced by a moving pedestrian.