Physically Based Modelling of the Material and Gaseous Contaminant Interactions in Buildings: Models, Experimental Data and Future Developments

Abstract

Although potentially having a significant influence on indoor air quality (IAQ), interactions between building materials and gaseous contaminants have often been neglected or crudely modelled in IAQ simulation tools. During the past 20 years, empirical source and sink models have progressively given way to physically based models; but confusion still remains on their applicability, as well as on the adequate experimental data to input for the model parameters. Thus, demonstration is first made that models relating macroscopically the room air phase and material concentrations through adsorption and desorption constants are not scientifically sound. Instead, elemental models combining diffusion equations and local sorption equilibria should be used. The compilation of sorption and diffusion data presented in the second part of this chapter underlines the fact that such data cannot be considered independently from the mass transport equations used to fit the measurements. As a result, a thorough analysis of diffusion processes in polymers and porous media is presented in order to define and relate the diffusion coefficients. Finally, the last part of the chapter discusses the way in which existing models could be extended to account for the contributions of temperature, multi-component mixtures, humidity and chemical transformations within materials. Still based on fundamental considerations, the proposed methodology consists of implementing new functionalities to describe the temperature dependence of the model parameters, elemental models representing the interactions between gaseous contaminants and water, as well as kinetic models coming from the fields of atmospheric and surface sciences.

Assessment of indoor HONO formation mechanisms based on in situ measurements and modeling

“…Indeed, several indoor measurement campaigns did not give enough details about the experimental condi ons and the geometries of indoor surfaces. Recently, Mendez et al 37 implemented in INCA-Indoor a scheme proposed by Blondeau et al 52 involving the use of the mass transfer coefficients from indoor air into a boundary layer near the surfaces. The thickness of the boundary layer is calculated depending on parameters such as the room characteris cs, the air velocity, and the characteris c length of the material.…”

A Study on the Similarities between Water Vapor and VOC Diffusion in Porous Media by a Dual Chamber Method

“…The values obtained by the two methods are in the same order of magnitude, but the diffusion coefficient by dual chamber was larger than that using the MIP method. Possible reasons may include, but are not limited to: (i) uncertainties in both the MIP and dual chamber measurements; and (ii) possible surface diffusion that is not accounted for in the calculation based on the MIP measured pore volume distribution [20]. Further investigation into this is needed.…”

A New Experimental Method for the Determination of Emittable Initial VOC Concentrations in Building Materials and Sorption Isotherms for IVOCs

“…The objective of this study was to develop a novel method for determining initial VOC concentrations and the sorption isotherm. A dual chamber method for determining the diffusion coefficient was developed by Xu et al [10].…”