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ItemShape Machine: shape embedding and rewriting in visual design(Georgia Institute of Technology, 2021-07-27) Hong, Tzu-Chieh KurtShape grammar interpreters have been studied for more than forty years addressing several areas of design research including architectural, engineering, and product design. At the core of all these implementations, the operation of embedding – the ability of a shape grammar interpreter to search for subshapes in a geometry model even if they are not explicitly encoded in the database of the system – resists a general solution. It is suggested here that beyond a seemingly long list of technological hurdles, the implementation of shape embedding, that is, the implementation of the mathematical concept of the “part relation” between two shapes, or equivalently, between two drawings, or between a shape and a design, is the single major obstacle to take on. This research identifies five challenges underlying the implementation of shape embedding and shape grammar interpreters at large: 1) complex entanglement of the calculations required for shape embedding and a shape grammar interpreter at large, with those required by a CAD system for modeling and modifying geometry; 2) accumulated errors caused by the modeling processes of CAD systems; 3) accumulated errors caused by the complex calculations required for the derivation of affine, and mostly, perspectival transformations; 4) limited support for indeterminate shape embedding; 5) low performance of the current shape embedding algorithms for models consisting of a large number of shapes. The dissertation aims to provide a comprehensive engineering solution to all these five challenges above. More specifically, the five contributions of the dissertation are: 1) a new architecture to separate the calculations required for the shape embedding and replacement (appropriately called here Shape Machine) vs. the calculations required by a CAD system for the selection, instantiation, transformation, and combination of shapes in CAD modeling; 2) a new modeling calibration system to ensure the effective translation of geometrical types of shapes to their maximal representations without cumulative calculating errors; 3) a new dual-mode system of the derivation of transformations for shape embedding, including a geometric approach next to the known algebraic one, to implement the shape embedding relation under the full spectrum of linear transformations without the accumulated errors caused by the current algorithms; 4) a new multi-step mechanism that resolves all cases of indeterminate embeddings for shapes having fewer registration points than those required for a shape embedding under a particular type of transformation; and 5) a new data representation for hyperplane intersections, the registration point signature, to allow for the effective calculation of shape embeddings for complex drawings consisting of a large number of shapes. All modules are integrated into a common computational framework to test the model for a particular type of shapes – the shapes consisting of lines in the Euclidean plane in the algebra U12.
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ItemA FORMALIZED URBAN PROSUMER MODEL: SUPPORT OF AUTOMATED SIMULATION AND DESIGN OPTIMIZATION(Georgia Institute of Technology, 2021-07-26) Jung, Yun JoonMany global cities have announced ambitious net-zero energy consumption targets or net-zero CO2 emissions plans. It is well recognized that this can only be realized through a mix of measures such as efficiency improvements at the sites of consumption and decentralized energy generation, storage and delivery mechanisms. This transition will not happen without major changes to energy supply networks, especially in the way they enable frictionless inclusion of renewable energy sources and local supply, for instance through microgrids. At the urban scale, buildings constitute the major consumers of electricity and their integration through building-to-building and building-to-grid controls is crucial to realize efficient energy sharing in urban energy networks. Over the last decade, the building energy simulation domain has moved its focus from traditional local studies to urban energy studies. The main objective of this thesis is to make a contribution to this growing research domain, especially in enabling the simulation of energy supply networks in a robust manner and at a large scale. It is possible to simulate such networks with customized software but considering that there is no systematic way to specify urban energy models (especially with multiple concurrent control topologies), the simulation software has to be hand-customized which leads to opaque simulations that moreover are hard to use for rapid variant explorations. The thesis argues that this can be overcome by the development of an urban prosumer (UP) schema that facilitates the specification and automated mapping of an urban energy network into simulations, focusing on the effective specification of controls outside the software. At a high level, the UP schema is comprised of a physical and a logical layer. The physical layer conceptualizes existing urban energy networks using directed graphs for energy transport between nodes. The logical layer conceptualizes how the dynamic processing (reasoning) of sensor data leads to instructions to a set of actuators that execute the control. In doing so, two levels of control are distinguished: (a) “private” (mostly rule-based) control such as the internal HVAC system following temperature setpoints, (b) “public” control that is exposed to the rest of the network and thus within the scope of the UP schema. Public control can be either rule-based or optimal control, the latter driven by an appropriate optimality criterion, defined at a network scale. In design situations, the optimality criterion is not limited to control variables but can also include design parameters, such as building design parameters, solar installation sizes, community battery size, and the number of EV charging stations. Mixed-integer non-linear programming (MINLP) is used to solve optimal control problems. The genetic algorithm is employed to solve design optimization problems. The case studies using the UP schema for ten Georgia Tech campus buildings are presented. The purpose of the case studies is to prove that the UP schema can facilitate simulations involving different levels of controls. The simulations target optimal energy decisions for the selected campus buildings in the presence of PV and electricity battery. Additionally, three residential buildings in California are chosen to investigate how the design and control parameters act together to avoid the power outage situation with the embedded UP schema in the simulation platform.
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ItemIMPACT OF ELA CALIBRATION METHODS ON BUILDING ENERGY MODEL FIDELITY AND FITNESS(Georgia Institute of Technology, 2021-05-05) Althobaiti, Mohanned Mutlaq M.As building performance is increasingly improved and building energy consumption decreases, a greater percentage of the total energy loss of a building occurs through envelope leakage. This leakage is characterized by the effective leakage area or ELA, which is a proxy parameter to what is essentially a complex flow phenomenon through cracks driven by pressure differences. Moreover, different façades and façade parts have different ELA and are typically subjected to different pressure differences in a given wind condition. This poses major challenges to building energy models. Current building performance simulation (BPS) uses software modules that approximately calculate envelope infiltration, but the literature shows that their calibration and validation is still unsatisfactory. In fact, calibration and validation of BPS models is still an important subject of study in our quest to improve the fidelity of simulation-based predictions in various applications. The high level of interaction and subsumption between parameters can result in a model that approximates the measurements well (and thus meets the ASHRAE auditing threshold) but whose “best estimates” of parameters are unreliable. This can be a problem in performance contracting when limits have been agreed on certain parameters such as ELA and U-value. It can also be problematic in the use of the model for certain performance assessments. This thesis exemplifies the underlying issues by comparing the results of direct and indirect calibration at different fidelities. The study focuses on the calibration of building energy models of existing buildings. It does so by conducting calibration for different experiments, i.e., for different sources of data, and for different model fidelities. The calibration is anchored around ELA and its impact on “best estimates” of other parameters is verified. The study is done with explicit quantification of uncertainties in the experiments as well as in model parameters. The two major experiments considered are (a) direct ELA calibration through tracer gas experiments, (b) indirect ELA calibration with consumption data enhanced by spot temperature measurements. Two case studies on existing buildings are performed. The thesis develops a new framework to address calibration and validation for different combinations of data and model fidelity, where each combination leads to probability distributions of the calibration parameter set. For each combination the ultimate aim is to determine the fitness of the resulting building energy model for given application studies such as building energy benchmarking, fault detection, unmet hour verification, etc. This requires the introduction of a novel fitness measure that determines the confidence level of a particular calibrated model for decisions in a predefined building performance assessment scenario. The thesis shows an early example of how to develop and quantify fitness. The results will be meaningful for better understanding façade infiltration, better understanding of the limits of calibrated models, and the way this translates into fitness of the resulting model. The thesis focuses exclusively on existing buildings, but its findings may lead to large scale data sets of calibrated ELA values in existing buildings, that may find their way into better ELA quantification in energy models of new designs.
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ItemGentrification or Health-promoting Resource? Long-term Residents' Perceptions and Use of the Atlanta BeltLine(Georgia Institute of Technology, 2021-01-27) Matic, ZoranaInvestments in green infrastructure such as multi-use urban greenways are made with the goal to improve the residents' health by creating space for physical activity, recreation, and social interactions, providing opportunities for active transportation, and increasing exposure to nature's healing effects. Despite the host of benefits, regreening initiatives in lower-income neighborhoods can also catalyze 'green' or 'environmental' gentrification. There is growing empirical evidence that gentrification affects the residents' health and well-being, both positively and adversely. The previous scholarship mostly focused on greenway users and has mainly adopted quantitative methods (such as observation and intercept surveys) to measure green infrastructure use, activity patterns, and users' satisfaction. However, the research on the incumbent residents living adjacent to a newly developed greenway is limited. It is still not fully understood whether incumbent residents have a positive perception of newly installed greenways, the extent to which they take advantage of these new resources, and whether the new greenways mostly attract new and habitually active residents. This research seeks to fill this gap by exploring the interrelationships between green infrastructure, green gentrification, and long-term residents' health and healthy behaviors in Atlanta, which that has recently invested into and developed a number of green infrastructure projects. This dissertation has two studies. Capitalizing on free and readily available U.S. census data, the first study proposes a replicable quantitative approach for developing a composite socioeconomic index as a tool for identifying and measuring gentrification. In the second study, this research closely looks at two historically African American neighborhoods in the early stages of gentrification and adjacent to the new BeltLine recreational trail. By interviewing long-term residents, this research seeks to develop a deeper understanding of green gentrification from their vantage point and to examine their responses to new greenway and opportunities for adopting health-promoting behaviors. The quantitative analysis indicated that nearly half of eligible census tracts in Atlanta are gentrifying, while two-thirds will soon be in various stages of gentrification. The census tracts within one-half mile of the BeltLine proposed path are gentrifying at a slightly faster pace. The Atlanta's gentrification patterns echo the previous findings on the proximity of the BeltLine and growing gentrification pressures in the trail-adjacent neighborhoods. Additionally, the results suggest the association between gentrification and residents' better self-rated health. The analysis found a consistent pattern of decreasing rates of residents who report low physical activity and poor self-rated health (both mental and physical) with increasing levels of gentrification. The interviews revealed much more nuanced responses to the trail construction and green gentrification. Most interviewees perceived and used the new trail as a health-promoting resource; while it enabled the habitual exercisers to maintain active lifestyles, it prompted some new trail users to be physically active. However, concerns regarding gentrification and feeling that new amenities cater to the 'gentrifiers' and not the existing community, in some cases acted as barriers to trail usage and regular physical activity. The findings suggest that perceptions of social environment entwine inextricably with perceptions of the physical environment and the extent to which groups or individuals take advantage of health-promoting resources. This study has important implications for future research and design of effective greening infrastructure to increase trail usage among long-term residents, particularly those who are not habitually active.