Modelling of Emission and Re-emission of Volatile Organic Compounds from Building Materials with Indoor Air Applications

The physical modelling of Indoor Air Quality (IAQ) suffers a lack of sorption data for the most common Volatile Organic Compounds (VOC) on building materials. This paper deals with an experimental facility that aimed to provide the sorption isotherms of gaseous contaminants on various materials. It was used to determine the sorption isotherms of acetone on chipboard, acrylic paint, and the gypsum core of commercially available gypsum board. After a brief introduction to fundamental principles of sorption, the experimental device is presented in detail. The results are reported and discussed, emphasising the description of the isotherm shapes and the possible partial reversibility of the sorption phenomenon for porous materials. The resulting curves are clearly non linear when dealing with gypsum and chipboard. Moreover, the sorption isotherms of acetone on gypsum were found to be different whether they were determined in the directions of increasing or decreasing concentrations. Many questions remain unresolved about the physico-chemical processes involved, the sorption data to be considered for the purposes of IAQ modelling, and the way to account for the observed phenomenon when modelling the sorption/diffusion contaminant transport in building materials.

Section: Introductionmentioning

confidence: 99%

Sorption Isotherms of Acetone on Various Building Materials

Tiffonnet¹,

Blondeau²,

Allard³

et al. 2002

“…where Cs = surface concentration (mgWm Neretnieks et al [61], in a conceptual study of a 21-compartment hypothetical room containing a PVC flooring material (active ingredient 2-ethylhexanol), supporting typical office furniture acting as sorbing sinks and secondary emitting sources, assumed that mass transfer in the solid material was by diffusion with no irreversible chemical reactions occuring. The authors proposed that VOCs can be held by solid material in three different ways in at least three different compartments of the material:…”

Section: Diffusion-convection Modelsmentioning

confidence: 99%

“…Indoor air emissions result from complex transport processes including evaporation and surface effects [49,[50][51][52], desorption and absorption [28,[53][54][55][56], internal diffusion [57][58][59] or diffusion-convection [47,60,61].…”

Section: Physical Modelsmentioning

confidence: 99%

Development of Robust Indoor Air Quality Models for the Estimation of Volatile Organic Compound Concentrations in Buildings

Ellacott¹,

Reed

1999

The increasing incidence of health problems associated with ‘tight buildings’ can be partly blamed on the emission of volatile organic compounds (VOCs) derived from human activity and the presence of a range of synthetic furnishings, office equipment and building materials. The development and nature of both empirical (statistical) and deterministic (physical) indoor air quality models to predict the concentration of VOCs in indoor air has been reviewed. The review identified a number of physical parameters including air exchange, sorption/desorption processes, source emission rates and source emission decay profiles as important considerations in the establishment of a robust indoor air quality model. Such a model enables the health and safety professional to make cost-effective and informed decisions to improve indoor air quality and reduce health risk by minimising worker’s exposure to contaminated air inside buildings.

“…Others have developed physically based models to predict emissions of pollutants in an indoor environment. Based on fundamental theory, some investigators considered external diffusion [19][20][21][22][23][24][25], while others have emphasised internal diffusion [9,10,26]. Although these physically based models can provide an insight into the controlling mechanisms, it is difficult to estimate or measure the large number of parameters required by these models.…”

Section: Introductionmentioning

confidence: 99%

Modelling of Emissions of Total Volatile Organic Compounds in an Australian House

Guo

Murray

2000

A simplified indoor air quality (IAQ) model has been applied to predict IAQ in an Australian house, using environmental chamber measurements of source strengths, house ventilation and room size. Total volatile organic compounds (TVOCs) was used as the model pollutant in this study. The validity of the IAQ model was initially assessed by comparing model predictions with measurements in the house over a period of time. The root mean square error between the measured and predicted values was 0.039. This model explains 57% of the potential for error. The TVOC concentrations measured in the conventional house ranged from 60 to 162 µg·m^–3. These values are much lower than some published values (0.48–31.7 mg·m^–3) for new houses in Scandinavian countries and in the USA. The low TVOC concentrations obtained in this study probably result from the high ventilation rates in this conventional house and the use of low TVOC emission materials.