Date of Award

5-2014

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Planning, Design, and the Built Environment

Advisor

Blouin, Vincent

Committee Member

Kaye, Nigel

Abstract

Incorporating Phase Change Materials (PCMs) in construction materials can increase the thermal mass of a building. With this increase in thermal mass, PCMs are known to reduce the heating and cooling loads of a building significantly. During the past 10 years, studies have estimated potential reduction of energy consumption of buildings between 10 and 30 percent. This wide range is due to the large number of parameters that effect energy consumption and make the process of selecting the optimal type and amount of PCM challenging. In fact, extensive engineering studies are generally necessary to determine the practicality of PCM in any specific case. As a result, architects and engineers are reluctant to use PCM because of the lack of such a comprehensive study. In the United States, eight climate zones are identified on the basis of annual degree heating and degree cooling days. For a given building in a given climate, there exists an optimal melting temperature and enthalpy that can reduce the energy consumption and the payback period. In this research, the optimal properties of PCM boards are determined for all 15 representative cities. Additional topics discussed in this research are the sensitivity of the optimal properties of PCM and the effect of the average cost of energy on the selection of PCM. The effect of six independent variables on the performance of PCM boards is presented in detail and the climate types where PCM boards perform optimally are narrowed down. In addition, a new procedure is presented to study the temporal and directional melting and solidifying trend of the PCM placed in buildings. The energy consumption and hourly data for the PCM enhanced buildings are determined numerically using the Department of Energy software EnergyPlus, which calculates the energy consumption for heating and cooling a building under any climate and operation schedule. The software is run on a computer cluster for a wide range of properties from which the optimal values are extracted. The findings from this research suggest that, there are only a few climate types within the United States where the use of PCM boards in lightweight buildings are viable. While the market potential for PCMs in building energy improvements can be significant, its acceptance is hindered by its extraordinary high cost. Analysis of the performance of PCM boards against six independent variables suggests that the internal load is a crucial factor in determining the optimal performance of PCM. Therefore any guideline on the selection of proper PCM should be formulated predominantly on the basis of internal load and the internal mean air temperature.

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