Medium, matter, form, and process: dynamic hygrothermal polymeric membranes

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Smith, Shane, Ida
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Electronic thesis
Architectural sciences
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Existing knowledge of building envelope system performance and technology for processing humidity is embedded within, and biased by, a historic lineage of attempting to hermetically seal and mechanically control the passage of humidity into building interiors. This paradigm perpetuates an energy consumptive process, limits the ability for distributed user control of the thermal environment, and is also problematic to the extent that it may cause increased symptoms of sick building syndrome with an unbalanced psychrometric profile, poor ventilation, lack of natural daylight, and microbial contamination, through the reduction of protective microbial biodiversity. In addition, previous studies of mechanical desiccant systems fail to consider an integrated dehumidification function distributed within the building envelope system itself and rather emphasize a trajectory of improving isolated system efficiencies without consideration of holistic building design impact. Without consideration of a cultural shift with the potential of emerging material technologies for building envelope design, existing building technologies for hot-humid and hybrid moderate climates lack the effectiveness to simultaneously address environmental phenomena of humidity, light, heat, ventilation, and water recu-peration. If hydrogels are integrated into the design of exterior and interior building envelopes, then an effective dehumidification function could simultaneously be achieved in a multifunctional systemic approach that includes water recuperation, dynamic thermal capacitance, light diffusion, and ventilation actuation properties. This thesis proposes the design of hygrothermal polymeric membranes towards effective multi-scalar responsiveness to dynamic environmental conditions around and through building envelopes, including relative humidity, dry-bulb temperature, solar radiation, natural ventilation, and water recuperation regeneration cycles. This analysis is achieved by acquiring performance data from a series of experiments determining material behaviors, and crosslinking that data with a limited series of digital building-scale energy models in order to determine the viability of replacing existing models of humidity management with the proposed model of distributing intelligent hydrogel-based desiccant materials within building components such as shading assemblies and radiant structural components. These analytical models provide a foundational framework that can inform future research directions for building-integrated desiccant materials, particularly for hot-humid climates, especially with regards to energy conservation, adequate ventilation, microbial management, and water recuperation. The dynamic hygrothermal polymeric membrane research initiates a cultural shift in building envelope design by considering the dehumidification function as integral to the building envelope system and by conceiving of both exterior and interior environmental phenomena through the membrane as an interdependent ecosystem, effectively resulting in improved energy performance, improved natural daylighting, improved water conservation, improved ventilation quality, and improved thermal comfort through distributed control. These initial baseline studies inform prospective prioritization of environmental performance criteria for dynamic hygrothermal polymeric membranes with consideration of the influence of material limitations, economic limitations, and social implications. The design-based research is lensed through a theoretical framework of four causes in the design process: medium, matter, form, and process. Theoretically, the design research emerges from an analysis of the phenomena of medium (humidity), within an ecological imperative. This foundation for ecologically-based design research is balanced by an intention of reflexive sustainability, which encompasses aspects of subjectivity and cultural implications.
School of Architecture
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Rensselaer Polytechnic Institute, Troy, NY
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