Master of Science / Department of Architecture / Michael D. Gibson / The use of Natural Ventilation (NV) to cool buildings in mixed climates can conserve significant cooling energy. In mixed climates it is particularly important during the fall and the spring, where appropriately designed buildings should use very little energy for heating or cooling. Natural ventilation is also important in residential buildings, where internal heat gain can be managed, making cooling by natural ventilation easier. Earlier investigations have clearly shown the economic, social, and health benefits of the use of NV in built environment. Studies have shown that increased airflow or air-speed during ventilation can bring a significant rise in comfort range which further reduces the cooling energy required to maintain comfort. The climatic data of the central United States (U.S.) shows that the availability of frequent high speed wind and favorable seasonal humidity conditions make natural ventilation feasible in late spring and early fall, where NV can offset most of the cooling demand for a home or multifamily residential unit, though it is not possible to maintain thermal comfort during the entire summer with NV alone. In mixed climates, NV for multifamily residential units has not been investigated thoroughly. According to 2009 International Residential Code, multifamily residential buildings are typically designed to use a code minimum amount of operable or ventilating windows, 4% of the floor area being ventilated, while also using lightweight construction methods (such as wood framing) that is prone to fast thermal response during the overheated periods of the year. While climate may favor the use of NV in these building types, the sizing of windows and the building construction type limit the potential to save energy with NV. This study hypothesized that the maximum benefits from NV in the climate of the central U.S. requires further optimization of window openings beyond the energy code minimum, and a construction system incorporating mass that can slow thermal response during overheated periods. During the study, the climatic data of the central US was scrutinized to understand the most suitable time frames where NV could be applied in order to maintain indoor thermal comfort in various construction systems in residential buildings: mainly lightweight using wood framing, and heavier construction using concrete and masonry. The location of the housing unit, first level or second level, was also examined to account for the differences in thermal gains and losses as a result of ground coupling and additional heat gain from the roof. Further, computational fluid dynamics evaluated the comfort achieved with different ventilation areas. Change in comfort hours by using NV tested the practicability of the use of NV to maintain indoor thermal comfort for different scenarios. The study concluded with design recommendations for building orientation, operable window size, and construction type as these factors relate to thermal comfort and the optimization of multifamily residential buildings to utilize NV for energy savings in the U.S.

<p>This dissertation focuses on the creation of a paradigm shift in building innovation. Challenges in achieving building energy-efficiency at scale highlight the complexity of the building performance problem, which is embedded with social, cultural, physical, environmental, and economic factors. Traditional approaches to building design have difficulty accounting for these multi-faceted variables and related longitudinal barriers and intangible impacts. Firstly, key stakeholders and their economic constraints change throughout time, and this variability is not traditionally considered upfront or addressed throughout a building’s operation. Secondly, buildings have social, cultural, environmental and economic implications that are difficult to quantify and evaluate against strictly functional design objectives. Therefore, current deeply technical and often system-specific building design strategies could benefit from whole-building solutions that account for this complexity and enable a paradigm shift in design toward human-centered outcomes (i.e., well-being, health, financial sustainability) and effective (i.e., equitable and sustainable) buildings. </p> <p>To drive this shift, an impact-based innovation framework was employed to pursue system-level and ecosystem-level strategies to optimize longitudinal building value assessment and distribution. First, a grounded theory study was pursued which identified gaps in current design practice that miss underlying building subsystem interactions which influence building performance. A system-level taxonomy of the building was then defined, linking identified sub-system synergies to functional, emotional and social building benefits for inhabitants. Then, an exploratory mixed-methods study was pursued, yielding a longitudinal building value framework that helps characterize key stakeholders, building design choices, and shared efficacy metrics. Building on these inputs, a multi-stakeholder, longitudinal building value assessment model was developed. The model was tested on two residential building development scenarios, highlighting its ability to capture the true impact of buildings on affected stakeholders over time in terms of tangible and intangible building costs and benefits. Finally, business model innovation concepts were employed to identify specific changes in stakeholder value delivery and capture strategies that could redistribute building costs and benefits over time, and thereby facilitate a shift in the paradigm of design and value capture in the residential building industry. </p>