The concept of using multiple cavities walls systems (MCWS) and redistributed insulation in providing high thermal efficiency in walls while enhancing its capacity to control with intruded moisture was tested through four wall system designs. Twelve walls having fixed number of cavities were tested simultaneously with a reference wall for summer temperature and humidity conditions. Results show lower heat flow rates for MCWS walls with equally distributed polyisocyanurate insulation panels (50mm on both sides of a central cavity) as compared to the reference wall with RSI 2.29 (R-13) despite the evaporative air cavities present in the MCWS walls. Reduction in the indoor insulation to 25 mm resulted wider variation in recorded heat flow rate but still thermally efficient than the reference wall. MCWS walls with balanced but only 25 mm PIR insulation on both sides of the wall cavity showed variable performance. When PIR insulations (50mm) were placed only at the outer portion of the central wall cavity, the reference wall showed lower (better) flow rate than MCWS.

abstract: Natural resource depletion and environmental degradation are the stark realities of the times we live in. As awareness about these issues increases globally, industries and businesses are becoming interested in understanding and minimizing the ecological footprints of their activities. Evaluating the environmental impacts of products and processes has become a key issue, and the first step towards addressing and eventually curbing climate change. Additionally, companies are finding it beneficial and are interested in going beyond compliance using pollution prevention strategies and environmental management systems to improve their environmental performance. Life-cycle Assessment (LCA) is an evaluative method to assess the environmental impacts associated with a products' life-cycle from cradle-to-grave (i.e. from raw material extraction through to material processing, manufacturing, distribution, use, repair and maintenance, and finally, disposal or recycling). This study focuses on evaluating building envelopes on the basis of their life-cycle analysis. In order to facilitate this analysis, a small-scale office building, the University Services Building (USB), with a built-up area of 148,101 ft2 situated on ASU campus in Tempe, Arizona was studied. The building's exterior envelope is the highlight of this study. The current exterior envelope is made of tilt-up concrete construction, a type of construction in which the concrete elements are constructed horizontally and tilted up, after they are cured, using cranes and are braced until other structural elements are secured. This building envelope is compared to five other building envelope systems (i.e. concrete block, insulated concrete form, cast-in-place concrete, steel studs and curtain wall constructions) evaluating them on the basis of least environmental impact. The research methodology involved developing energy models, simulating them and generating changes in energy consumption due to the above mentioned envelope types. Energy consumption data, along with various other details, such as building floor area, areas of walls, columns, beams etc. and their material types were imported into Life-Cycle Assessment software called ATHENA impact estimator for buildings. Using this four-stepped LCA methodology, the results showed that the Steel Stud envelope performed the best and less environmental impact compared to other envelope types. This research methodology can be applied to other building typologies. / Dissertation/Thesis / M.S. Architecture 2013

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The American Society of Heating, Refrigerating and Air conditioning Engineers suggests that the building sector represents over 30 percent of our national energy consumption (Parsons, R., 2001). Embodied energy in components of building construction can represent as much as five to ten years of operating energy. Building materials such as concrete, steel and glass require significant amounts of energy for production, and therefore are important when calculating embodied energy in buildings (Keable, 2007; Rypkema, 2007). Because of the relatively large area and volume of related components, the building enclosure system represents a major factor when calculating embodied energy. Alternative materials could be incorporated by adapting traditional and vernacular building approaches to today's standards, for example, compressing soil blocks for use as external walls in buildings that can be applicable to almost any climate including rainforests and cold climates. As an alternative to high-embodied energy materials used for enclosure systems, compacted earth-based enclosure systems may be a viable option, particularly if developed and applied as a pre-manufactured modular system. This study seeks to both quantitatively and qualitatively explore the potential development of earth-based building curtain wall systems. Using modified ASTM test protocols for building enclosure systems and components, alternative earth-based panels were compared. The results suggest that earth-based panels may be a viable option for curtain wall systems but its performance is highly dependent on the composition of the panels. The results of the tests are summarized. / Master of Science

Moisture induced damages to building envelopes can result in microbial growth possibly affecting the health and wellbeing of occupants. Recent failing structures and damaged buildings indicate a lack of tools to estimate risk of mould growth and moisture damage. In this work a so-called mould resistance design (MRD) model has been applied for mapping the risk for mould growth on a number of wood-containing wall structures. The MRD model introduces an engineering approach to moisture safety design in a similar way as for structural design, where load and resistance is compared. The MRD model introduces and quantifies the concepts of climatic exposure and material resistance and compares them through an MRD index. This MRD index incorporates a limit state, which gives the critical dose of exposure for a given resistance to initiate onset of mould growth.   Three conceptual wall structures were evaluated and analyzed in terms of MRD index: two wall systems with an air gap and one wall system without. A parametric study investigating the effect of parameter variation on MRD index was conducted. Evaluated parameters were: climate (geographic location), orientation, air changes per hour in the air gap, driving rain penetrating the facade layer, exterior plaster properties and wood type. The simulations were performed using the hygrothermal calculation software WUFI. The results indicate that the wall systems with a ventilated air gap performs better in terms of MRD index i.e. suggests a lower risk of initiation of mould growth than the wall system without air gap. The results of orientation variation show that wall systems perform differently dependent on layering structure. The inherent water sorption properties of the exterior plaster are shown to have a large effect on the results. In addition, uncertainties were found on how to accurately include hydrophobicity as a parameter in the model. The report concludes that geographical location and its specific climate is the most important parameter to consider when designing for moisture safety. The MRD model is recommended to be used in combination with traditional moisture safety evaluation.

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