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Integrated Hygrothermal Performance of Building Envelopes and Systems in Hot and Humid Climates
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In hot and humid climates the interior and exterior environmental loads that building envelopes must respond to are larger than many other climatic conditions. Moisture-originated failures in low-rise residential buildings have put a significant pressure to change construction codes in North America. Solutions to moisture induced problems may be difficult when several interacting mechanisms of moisture transport are present. A new approach to building envelope durability assessment has been introduced in North America; a moisture engineering approach. This requires system information about the wall systems as constructed along with aging characteristics coupled with advanced modeling that 0 term allow the designer to predict the Iong-term performances of building envelope systems. This permits the comparison and ranking of individual building envelope systems with respect to total hygrothermal performance. Critical information can be obtained by investigating the one to one relationships of a building envelope to interior and exterior environments, however, the total behavior of the actual whole building is not accounted for. This paper goes one step further, by incorporating the individual hygrothermal performances of all walls, roof, floor and mechanical systems. The direct and indirect coupling of the building envelope and indoor environment with HVAC system are included in the analysis. The full house hygrothermal performance of an aerated concrete wall system are examined for a hot and humid climate. The hour by hour drying potential of each system was then numerically analyzed using weather conditions of Miami (hot and humid climate). The results clearly demonstrate the limited drying potential for the wall system in that climate. Furthermore, the selected exterior thermal insulation strategies and interior vapor control strategies in this study clearly show the critical behavior of the full house with respect to drying initial construction moisture. The results show the importance of the total hygrothermal behavior of the whole house to the coupling between the various envelope parts, interior and exterior environments and HVAC system. From these results moisture control strategies are identified for the whole house hygrothermal performance.
Karagiozis, A. N.; Desjarlais, A.; Salonvaara, M. (2000). Integrated Hygrothermal Performance of Building Envelopes and Systems in Hot and Humid Climates. Energy Systems Laboratory (http://esl.tamu.edu); Texas A&M University (http://www.tamu.edu). Available electronically from