ORCID Identifier(s)

0000-0002-6848-1125

Graduation Semester and Year

2019

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering

Department

Civil Engineering

First Advisor

Mohsen Shahandashti

Abstract

The majority of building energy consumption is used to heat and cool enclosed spaces. An innovative ultra-high-performance fiber-reinforced concrete (UHP-FRC) façade system could potentially reduce this energy consumption by utilizing UHP-FRC’s high structural strength and ductility hence more space for insulation. The energy performance assessment of innovative façade systems such as UHP-FRC panels could be misleading if the effect of building types and climate contexts on building energy consumption is not considered. Moreover, thermal bridging and hygrothermal analyses of UHP-FRC panels are needed to investigate the heat and moisture transfer within the panels. The main objectives of this study are (1) analyzing of heat and moisture transfer within the proposed UHP-FRC façade panel in a detailed assembly scale, (2) investigating the effect of panel connections in the hygrothermal performance of UHP-FRC façade panels, (3) investigating the combined effect of different building types and climate conditions on these panels’ energy performance under uncertainty, and (4) identifying and analyzing hidden underlying patterns in simulated data through knowledge discovery and pattern recognition. A Numerical heat and moisture transfer simulations were conducted to evaluate the amount of thermal bridging and the risk of mold growth within innovative UHP-FRC façade systems. The results of the thermal bridging analysis showed that the UHP-FRC panel provides unique thermal properties with higher thermal resistance compared with the conventional panel assembly. The UHP-FRC panel assembly minimizes the thermal bridging by eliminating the structural rebars. A transient, coupled heat and moisture transfer analysis was conducted in order to investigate the effect of panel connections in the hygrothermal behavior of facade panels. The results of heat hygrothermal assessment showed that steel connections could significantly reduce the thermal resistivity of façade panels by converging heat fluxes and acting as thermal bridges within façade panels. The results also showed that the steel connector of the panel to foundation connection had ten times higher maximum heat flux compared to the other connections. In addition, the results of moisture transfer showed that air gaps between the panels had higher moisture flux compared to the other layers in the connections. Therefore, new connection designs and materials are essential for innovative façade systems, such as UHP-FRC panels, to effectively exploit the potential opportunities provided by façade systems. A probabilistic simulation-based building energy performance analysis was also conducted to investigate the combined effect of different building types and climate conditions on the energy performance of UHP-FRC panel systems. The analysis was conducted for fourteen U.S. Department of Energy prototype buildings in fifteen climate zones (210 scenarios). The results showed that the energy savings of using UHP-FRC panels depend on the building type and climate condition. On average, energy savings are higher in colder climates (e.g., Fairbanks) than those in temperate climates (e.g., San Francisco). Also, buildings dominated by internal loads seem to benefit the least from UHP-FRC. A data-driven framework was developed to extract hidden information and underlying structure from the thermal behavior of UHP-FRC façade systems in a set of scenarios and provide recommendations for designers to select energy-efficient façade systems. In the proposed framework, clustering analysis was used to partition simulated data into different subsets with distinct patterns. Then, the association rule mining (ARM) technique was applied to each dataset to extract rules as recommendations for positive, negative, and neutral energy savings related to the UHP-FRC façade panel. Results highlighted the applicability of the proposed methodology in facilitating the energy performance analysis of UHP-FRC panels in different building contexts. This methodology can be used by designers as a decision support system to provide simple recommendations in the early stages of building envelope designs to obtain high-performance buildings. These findings contribute to the body of knowledge by highlighting the applicability of proposed methodologies in investigating the energy performance of building façade panels in both assembly-scale and building context. It is expected that these methodologies provide building engineers with essential means to objectively appraise the energy performance of innovative façade systems in both assembly-scale and building context.

Keywords

Ultra high performance fiber-reinforced concrete, Innovative façade system, Thermal bridging analysis, Hygrothermal assessment, Energy performance analysis, Building façade systems, Data mining, Clustering analysis, Association rule mining, Knowledge discovery, Panel connections, Coupled heat and moisture transfer, UHP-FRC facade panel

Disciplines

Civil and Environmental Engineering | Civil Engineering | Engineering

Comments

Degree granted by The University of Texas at Arlington

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