Numerical study of the energy efficiency of the building envelope containing multi-alveolar structures under Tunisian weather conditions

The study of the thermal inertia of buildings is a subject of major interest. The thermal insulation and the nature of the wall sensitively modify the inertia of the building and are the solutions to improve the energy efficiency of the envelope. The roof is well exposed to solar radiation in summer and contributes to significant losses in winter due to convective exchanges. To lead to a thermal comfort, a thermal insulation is necessary. In this context, we carry out a numerical study of the thermal behavior of a building with two zones in variable meteorological conditions for a Tunisian climate (region of Sousse) based on the thermoelectric analogy and using the nodal method as a numerical method. The object of this work is to study the effect of the thermal inertia of the roof equipped with a multi-alveolar structure on the thermal behavior of the air inside the room and on its energy consumption. Taking into account the energy input of occupant, a complete model was established to increase the accuracy of the calculations. The results show that the multi-alveolar structure placed on the outside of the roof reduces energy consumption during the winter period when the alveolar structure is placed in the conductive direction and during the summer period when the alveolar structure is placed in the insulate direction.

Abstract 16158: Comparative Effects of Bone Marrow Derived versus Umbilical Cord Tissue Mesenchymal Stem Cells in an Experimental Model of Bronchopulmonary Dysplasia

Introduction: Bronchopulmonary dysplasia (BPD) or chronic lung injury of newborn is a life-threatening condition in preterm infants with few effective therapies. Mesenchymal stem cells (MSC) are a promising therapeutic strategy for BPD. The ideal MSC source for BPD prevention is however unknown. Umbilical cord tissue (UCT) MSC may potentially have more anti-inflammatory and pro-angiogenic properties. Hypothesis: We hypothesized that the UCT-MSC will have superior lung regenerative effect in BPD owing to superior anti-inflammatory and pro-angiogenic properties as compared to BM-MSC. Methods: Newborn rats (n=10-12/group) were randomly assigned to normoxia or hyperoxia (85% O 2 ) from postnatal day (P) 1 to 21 were given intra-tracheal (IT) BM or UCT-MSC (1 x 10 6 cells/50 μl), or placebo (PL) on P3. Results: Hyperoxia PL-treated pups had marked alveolar simplification, vascular rarefaction, remodeling and lung inflammation. Administration of both BM-MSC and UCT-MSC significantly improved alveolar structure, vascular density, pulmonary hypertension, vascular remodeling and lung inflammation. However, the improvement in alveolar structure and lung inflammation was more marked in hyperoxic pups who received UCT-MSC. In vitro studies demonstrated greater TSG-6 and IL-10 expression in UCT-MSC as compared to BM-MSC. Moreover, lung epithelial cells incubated with UCT-MSC conditioned media had greater wound healing following scratch injury. Conclusion: These findings demonstrate that while both BM and UCT-MSC have lung regenerative effects, UCT-MSC have greater anti-inflammatory and alveolar protective effects in experimental BPD. These findings have significant implications for cellular therapy in BPD, as it suggests that UCT-MSC are a superior cellular source for preterm lung protection.