title: Experimental and numerical investigations of phase change material and night ventilation characteristics in buildings
Creators: name: Solgi, Ebrahim
Publisher: name: Griffith University
Year: 2019
Subjects: subject: Thermal energy storage
subject: Phase change materials
subject: Night ventilation
subject: Energy-efficient buildings

description: As a key consumer of energy, and producer of greenhouse gas emissions, the building industry can play a pivotal role in reducing the global energy and carbon footprint. Thus, the application of passive techniques in buildings has gained particular attention. These techniques, with minimal auxiliary energy load, can mediate between the external climate and comfortable indoor conditions, while providing an aesthetically pleasing indoor environment. Thermal energy storage is considered an essential component when using passive techniques. The primary aim of energy storage incorporated into buildings using passive strategies is to implement approaches for efficiently controlling the time lag between building energy demand and outdoor energy sources. Examples of passive strategies are advanced thermal energy storage (TES) and night ventilation (NV). Phase change materials (PCMs) as a salient example of advanced TES, have received remarkable attention for their use in energy-efficient buildings. PCMs, which mainly store energy thorough latent heat, can be conveniently integrated into building envelopes as productive lightweight thermal mass. PCMs have also been of paramount interest as compact components, since they can alleviate building energy loads and be easily coupled with other passive/active systems. Given that the role of TES in ameliorating the effectiveness of passive strategies such as NV is critical, recent years have produced a renewed interest in utilizing PCMs as efficient-lightweight thermal mass in preference to traditional sensible heat storage. Passive cooling techniques, such as NV, with an efficiency that is highly conditional upon thermal mass capacity, have been commonly used in conjunction with sensible thermal mass; however, with the proliferation of PCMs, NV can be reconsidered as an effective cooling strategy for lightweight construction. NV, as a well-established passive cooling strategy, uses the cool of night to release the daily stored heat; then during the subsequent warmer daytime the cooled TES can moderate indoor temperature. In countries with a range of climatic zones such as Australia, where the application of lightweight structures is of great importance, and where energy consumption is mainly targeted at the cooling demand, the use of PCMs and NV can be highly productive and applicable in a wide range of environments. However, very little is currently known in regard to the efficacy and requirements of employing PCMs in different Australian climatic zones, either in isolation or in combination with NVs. This research examines the key variables of PCM-enhanced buildings, such as the material properties and coupled thermal insulation, through a parametric study that includes NV efficiency. An optimal PCM-based TES is closely analysed in four major Australian climates, with respect to building and material characteristics and energy consumption. This dissertation follows experimental verifications, using a full-scale calorimeter, with in-depth numerical simulations of the validated model. This dissertation delivers some insights into the aforementioned TES and NV topics, and makes a contribution to building physics by providing building designers and researchers with the basis for practical applications.