A good design of a natural ventilation system maintains harmony between the local climates, space sensible heat loads, and the design of operable openings (windows). Poorly designed systems can perform miserably even in the best climatic conditions. Several factors such as building orientation, building massing, effective opening areas and their locations, relative height differences, internal heat loads, furniture and seating arrangement within the occupied spaces can affect the performance of natural ventilation systems. This presentation will discuss basics of natural ventilation and with the help of case studies demonstrate how basic analyses can help predict number of hot and comfortable hours for occupants and how to optimize the performance of natural ventilation designs.

ASHRAE, through its Epidemic Task Force, provided timely leadership in responding to the COVID19 pandemic from March 2020 through June 2022. At the request of the White House, ASHRAE undertook its own project Warp Speed to build on that expertise for the future. In December 2022, the ASHRAE Board committed to quickly writing a standard to make buildings more resilient against infectious aerosols ahead of the next epidemic. In only four months the project committee created and won approval for ASHRAE Standard 241-2023. In this Lecture a member of the 241 project committee will provide a summary of the standard including its purpose, scope, and key requirements with supporting background.

Air is the primary carrier of heat, moisture, and contaminants in health care facilities such as patient rooms, isolation rooms, and operating rooms. The flow path of supply air plays an important role in determining the air velocities, air temperatures, concentration of contaminants, and path of airborne pathogens in these spaces. These factors in turn determine thermal comfort of occupants, indoor air quality, and potential for transmission of airborne pathogens. This presentation will focus on the importance of HVAC configuration on airflow distribution and flow path of airborne contaminants in patient rooms and operating rooms. In addition, this presentation will cover the applications of active chilled beams, radiant heating and cooling, and displacement ventilation in patient rooms.

Air is the primary carrier of heat, moisture, and contaminants in and around built environments. Airflow patterns determine the distribution of temperature, contaminant level, and importantly air quality and thermal comfort of occupants. System level HVAC designs cannot envision the potential risks due to poor airflow distribution. Such risks are realized only after commissioning and occupancy of the buildings. This presentation will show how Computational Fluid Dynamics (CFD) can help in identification and mitigation of such risks at early stages in the design. After providing a brief introduction to CFD, this presentation with the help of several case studies will show application of CFD to a wide variety of scenarios involving displacement ventilation, active and passive chilled beams, airflow patterns in enclosed spaces, radiant heating and cooling, smoke propagation in atria, clean rooms, data centers, patient rooms, plume dispersion from cooling towers, and several other situations related to built environment.

Displacement ventilation systems which are also referred as “stratified air distribution systems” work on the principle of thermal buoyancy – hot air due to lower density rises above the cold air. Stratified distribution systems are becoming popular due to their ability to provide better indoor air quality with low energy demand. Stratified air distribution systems come mainly in two flavors – traditional displacement ventilation (TDV) systems and the under floor air distribution (UFAD) systems. This presentation will cover the basics of stratified air distribution systems and discuss various design and operational parameters that affect their performance.

Air is the primary carrier of heat, moisture, and contaminants in laboratory facilities. The flow path of supply air plays an important role in determining the air velocities, air temperatures, concentration of contaminants, and path of contaminants in laboratories. Often high airflow rates or air change rates per hour (ACH) for laboratory spaces are specified to cover the risk of chemical exposure. Although high supply airflow rates can reduce the overall concentration of contaminants it may not ensure uniformity of concentrations at a low diluted level. Importantly, locations of high concentration, especially those in the breathing zone of occupants can pose potentially higher exposure risk. This presentation will focus on the importance of HVAC configuration on airflow distribution and flow path of contaminants in laboratories. In addition, this presentation will cover basics of air ventilation for laboratories and flow dynamics of fume hoods.

A good design of a natural ventilation system maintains harmony between the local climates, space sensible heat loads, and the design of operable openings (windows). Poorly designed systems can perform miserably even in the best climatic conditions. Several factors such as building orientation, building massing, effective opening areas and their locations, relative height differences, internal heat loads, furniture and seating arrangement within the occupied spaces can affect the performance of natural ventilation systems. This presentation will discuss basics of natural ventilation and with the help of case studies demonstrate how basic analyses can help predict number of hot and comfortable hours for occupants and how to optimize the performance of natural ventilation designs.

Airflow management within data centers is crucial for proper cooling and energy efficiency of data centers. Proper selection as well as proper placement of various data center equipment such as CRACs, perforated tiles, and racks play an important role in airflow distribution and cooling performance of data centers. This presentation will focus on basics of data center cooling and principles of air movement in data centers with a wide variety of examples involving raised floor and flat floor data rooms, air leakages through server cabinets and containment systems, and role of rack thermal mass during power shutdown. This presentation will also discuss plume dispersion in the equipment yard around the data centers and optimum placement of air cooled chillers.