Browsing by Subject "Perceived air quality"
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Item Clay-based materials for passive control of ozone and reaction byproducts in buildings(2016-05) Darling, Erin Kennedy; Corsi, Richard L.; Brown Wilson, Barbara; Juenger, Maria; Novoselac, Atila; Xu, YingTropospheric ozone that infiltrates buildings reacts readily with many indoor materials and compounds that are commonly detected in indoor air. These reactions lead to lower indoor ozone concentrations. However, the products of ozone reactions may be irritating or harmful to building occupants. While active technologies exist (i.e., activated carbon filtration in HVAC systems) to suppress indoor ozone concentrations, they can be costly and/or infeasible for dwellings that do not have these systems. Passive methods of ozone removal are an interest of building environment researchers. This dissertation involves (1) a review of the state of the knowledge on building materials and coatings that are intended to passively remove indoor ozone, especially clay-based materials; (2) a compilation of current data on ozone removal and reaction byproduct formation for these materials; (3) a model for ozone removal effectiveness for a selected clay-based material that is implemented in a hypothetical home; (4) a survey of the effects of a clay-based coating with and without ozone and a reactant source on human perceptions of air quality; (5) an investigation of the long-term potential for passive control of indoor ozone by two different clay-based surface coatings that were exposed to real indoor environments; and (6) development of a location-specific model to estimate the monetary benefits versus costs of indoor ozone control using passive removal materials. The above tasks were completed through ongoing reviews of the literature, experimental studies conducted in small and large environmental chambers, and in the field. Results of these studies suggest that clay or materials made from clay are a viable material for passive reduction of indoor pollution, due in part to clay’s ability to catalyze ozone. Human sensory perceptions of indoor air quality were shown to significantly improve when a clay-based plaster was present in an ozonated environment. Based on modeling efforts, effective passive removal of indoor ozone is possible for realistic indoor scenarios when clay-based materials are implemented. There is a growing number of papers that are published on the subject of clay materials and indoor environmental quality, but few that investigate the longer term impacts and performance of clay materials, especially ones that have been exposed to real indoor environments.Item Impacts of a clay plaster on actual and perceived indoor air quality(2011-08) Darling, Erin Kennedy; Corsi, Richard L.; Ying, XuPassive removal materials (PRMs) are building materials or furnishings that can effectively control indoor pollution without substantial formation of chemical byproducts and without energy penalty. To assess clay wall plaster as an effective PRM for improving air quality by controlling ozone, perceived air quality (PAQ) was determined in the presence of eight combinations of an emitting and reactive pollutant source (new carpet), clay plaster applied to gypsum wallboard, and chamber air with and without ozone. A panel of 18 to 23 human subjects assessed air quality in twin 30 m3 chambers using a continuous acceptability scale. Air samples were collected immediately prior to panel assessment to quantify concentrations of C5 to C10 saturated n-aldehydes and two aromatic aldehydes that are commonly produced by reaction of ozone with carpet. Perceived Air Quality was most acceptable and concentrations of aldehydes were lowest when only clay plaster or both clay plaster and carpet were present in the chambers without ozone. The least acceptable PAQ and the highest concentrations of aldehydes were observed when carpet and ozone were present together; addition of clay plaster for this condition improved PAQ and considerably decreased aldehyde concentrations. Ozone deposition and byproduct emissions of the clay wall plaster were also assessed using 48 liter stainless steel chambers. Clay plaster applied to gypsum wallboard that had been exposed in a test house (UTest House) for one year effectively removed 88% of the ozone, and emitted high aldehyde concentrations when exposed to high purity air that did not increase when the material was exposed to ozone. The outcome of these experiments leads to speculation that the clay plaster adsorbed contaminants in the test house and then re-emitted them upon exposure to clean air in the small chambers.