Date of Award

2018

Document Type

Open Access Thesis

Department

Civil and Environmental Engineering

Sub-Department

College of Engineering and Computing

First Advisor

Shamia Hoque

Abstract

Indoor environment is an important issue for the well-being of the society. In the United States more than 90% people spend their time indoor, indoor air pollution is more culpable than the pollution outside air. Two third of US businesses lose more than $100,000 per year due to workplace related illness. The trend of sharing the work space has an impact on total sick leaves in a company. Infectious particles released by a flu sufferer’s sneezing, coughing or even laughing can be a vital source. A thorough analysis on infectious particles’ transmission and air flow of the space can provide an effective solution to design and control of healthy indoor environment. The interior design i.e. furniture orientation, the air inlet and outlet locations and safe space distribution between the working zones can play a significant role in determining the most effective, energy efficient and healthy indoor layout.

In this study, a detailed computational fluid dynamics (CFD) simulations applying an Eulerian - Langrangian framework is performed to investigate the spread of infectious particles after sneezing in a ventilated office space and the length of time they reside in the breathing zone thus estimating the possibility of infection of another occupant. The observations from 18 distinct cases, varying ventilation rate (ACH 3, 5, and 7), ventilation pattern and furniture condition (with a partition wall only, and with partition wall and desk) demonstrate that only ACH increase cannot be a solution to reduce the risk of infection spreading, the ventilation pattern has a significant role and it defers with the room furniture conditions. Two types of ventilation pattern- mixed ventilation (MV) and displacement ventilation (DV) are assessed. MV pattern has been sub-divided into ceiling (inlet-outlet in the ceiling) and cross (inlet-outlet in opposite walls) ventilation.

Increasing ACH from 3 to 7 reduce ~45-50% more dead-zones in the room. At higher ACH, ceiling ventilation and displacement ventilation are more effective in removal of particles from the room as well as from the breathing zone. Moreover, the presence and absence of the furniture is an important factor to decide the ventilation rate and pattern to ensure healthier indoor space. With ACH 7, ceiling ventilation and MV-cross ventilations offers most favorable condition in a room with partition wall only and in a room with a partition wall and desk respectively. At lower ACH, MV-cross ventilation was found to be the most inefficient scheme for both room conditions. A preliminary study with multiple sized particles reveals particle number in the breathing zone did not vary substantially over time. The cost analysis shows that the monetary value to increase the ventilation rate is reasonable comparing to the annual loss from the inefficiency of the sick employees.

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