Masters Theses

Date of Award

5-1997

Degree Type

Thesis

Degree Name

Master of Science

Major

Environmental Engineering

Major Professor

Wayne Davis

Committee Members

Terry Miller, Gregory Reed

Abstract

The purpose of this study is to conduct a performance-based evaluation of the changing indoor air quality of a residential home under the condition of keeping a heating, ventilating, and air conditioning (HVAC) fan running continuously. To get a real world picture, the air samples were measured while the residential home was occupied by a family of four. However, the domestic activities were kept minimum during the period of data collection. An optical particle counter with multichannel analyzer was used for this study so that the concentration of particles in the particle size increments of interest could be measured simultaneously.

Two different types of the commercially available residential air filters were selected for this study. Two filters of each different type were used for the study of filtration efficiency. All four filters were tested to determine their initial (prior to dust loading) particle removal efficiencies in the range of 0.5 to 5.0 µm. The initial efficiencies of all filters were evaluated under normal air flow rate, as well as a higher air flow rate created by closing one of the three return air inlets in the residence. The measured efficiencies of the filters were studied to compare the consistency in filtration performance between two filters of the same type, the difference in performance between two different types of filters and under different flow rates.

Two filters of one type were also evaluated to determine their filtration efficiencies at the various stages after dust loading throughout the six weeks period of this study. The relationship between the efficiency and the associated parameters such as pressure drop and the increased weight of the filter was evaluated.

To evaluate the air quality, the sample data for the particle concentrations of indoor and outdoor air were measured on twelve days covering the whole period of six weeks. The results were plotted in various curves to visually evaluate the characteristics of the changing air quality with time, the effects by various incidental human activities noted, and the correlation between the indoor particle concentrations and the outdoor levels. The indoor particle concentrations prior to and during cooking were specifically measured in one case to evaluate the effect of cooking on the particle concentrations.

A deterministic model based on particle mass balance was utilized to evaluate the causes of, and ways to alter the indoor particle concentration levels. An experiment was also conducted to develop a basis for a cost effectiveness study of the case of keeping HVAC fan running continuously.

The observed results of this study indicate that the predominant particle distribution range of the subject residential home is in the category of "respirable particles" which are believed to be capable of causing reduction of lung function. It was concluded that keeping the HVAC fan continuously turned on would be an effective option for improvement of indoor air quality. Realizing the limited scope of this study, related topics for further study are also recommended.

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