Recent studies have shown that surface and gaseous contaminant interactions may play an important role in indoor air quality. Modeling is an important tool to improve our knowledge about the phenomena involved and define appropriate ventilation strategies. However, data for sorption isotherms and diffusion in building materials remain woefully lacking. This paper deals with the latter point. It aims at investigating a methodology based on an analysis of the material porosity first and then the application of Carniglia's mathematical model to determine the effective diffusivity of gaseous species in building materials. This methodology, whose main principles are presented in the first part of the paper, was applied to seven commonly found materials. Mercury intrusion porosimetry (MIP) tests, and the calculations using Carniglia's model, reveal typical total porosities and tortuosity factors for these materials. The analysis of pore size distributions (PSDs) also draws one's attention to the possible differences in the pore structures that may exist between two samples of the same type of material and the differences in the effective diffusivities of contaminants that may result from them. The computed effective diffusivities were subsequently compared to data from experiments carried out in the frame of the EC project MATHIS. An agreement was obtained, thus validating Carniglia's methodology - a methodology that offers many practical advantages compared to diffusion-cell methods.

Environmental concerns worldwide (climate change, global warming, etc.) are pushing to reduce the consumption of fossil fuels. The building sector is responsible for a third of greenhouse gas emissions (40% in France). In tropical countries, the main share of energy consumption in buildings is due to air conditioning systems. Indeed, in a resort of high standing, 60% of energy consumption is due to air conditioning. In the Indonesian context, which welcomes growing real estate projects on more or less isolated islands, it becomes important to put in place passive or autonomous buildings and the corresponding energy solutions. The energy efficiency of buildings is based on two pillars: an efficient building's design and on the effectiveness of the air conditioning system to achieve energy independency in a tropical environment. Considering the decreasing cost of PV cells, the solution to reduce the energy consumption of air conditioning proposed in this article covers a vapour-compression refrigeration system electrically powered by solar cells. To avoid the use of electric batteries, not sustainable in terms of carbon footprint (construction and recycling of batteries) and to overcome the problem of intermittency of solar energy, the choice fell on a variable speed compressor and a storage in a mixture of fatty acids (derived from coconut oil) as phase change material embedded in expanded graphite. The work also focuses on the energy performance of the storage system. This study describes the context and the air conditioning system chosen as a solution for a sustainable resort application in a tropical region. The design and characterization of the coupled PCM and compressed expanded graphite in a latent heat thermal energy storage is also detailed. It uses a TRNSYS simulation for the assessment of the cooling demand. Calculations for a prototype of 25 m 2 apartment showed that with a chiller of 8000 W and a surface of 14 m 2 of photovoltaic panels, it is possible to cool a hotel bedroom with solar energy. The consortium members work jointly at designing and optimizing the system: Indonesian members are focused on the PCM storage and French members are more dedicated to the hygrothermal behaviour of the hotel bedrooms.

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.

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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.

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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. —

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