Building Integrated Solar Thermal Energy Storage

Abstract

Economic development, improvement in living standards and globalization lead to raise the demand for energy. Consequently, to meet the increasing demand, fossil based energy reserves are over exploited causing global warming. Buildings (commercial and residential) have played a major role in further deepening the crisis of global warming. More than one third of the final energy consumption comes from building sector. The shift in global fuel use in buildings is partially due to changing end‐use consumption, with space cooling and electrical appliance energy growth leading electricity demand growth in buildings. Space cooling and appliances and other plug loads are the fastest‐growing building end uses; however, only space cooling has grown in energy intensity per unit floor area. The demand for space cooling become more intensive in countries having hot and humid climate or/and the countries lying in equatorial/tropical environment like India. Enhancing building energy efficiency through latent heat storage of the Phase Change Material will play a vital role in improving indoor thermal behavior of the building envelope. Consequently, it will improve the indoor thermal comfort, reduces the energy use for space cooling, and promotes the use of renewable sources of energy. PCM can be incorporated in the building envelope in many ways. One of the simplest and effective method of integrating PCM directly in building material is Macroencapsulation. This method not only improves the indoor thermal behaviour of the buildings, but also reduces the cooling load without or little compromising with the mechanical strength of the building structure. Following research gaps were identified in studies conducted so far, for improving the indoor thermal behaviour of the building by integrating the PCM in the building element (a) the effects of integrating Macroencapsulated PCM in the building envelope of the tropical xx environment like India have not been reported yet (b) Yearly/monthly or seasonal effect of embedding PCM in the building envelope on the indoor thermal behavior need to be addressed (c) It is required to identify the impact on cooling load in heavyweight constructed buildings due to incorporation of Macroencapsulated PCM in building envelope (d) It is needed to evaluate the thermal energy storage performance of a low cost commercially available PCM to be embedded in the building envelope. Based on these research gaps, the aim of this study was framed. The main aim of this study is to evaluate the indoor thermal behavior of the building envelope outfitted with Phase Change Material in the real outdoor tropical environment of India. Also, this study examines various thermal energy storage parameters of the PCM to assure the best possible performance when embedded in the building envelope. To achieve the above mentioned aim, an experimental setup of two similar building structures (called as cubicles), one is with macroencapsulated PCM and the other is without macroencapsulated PCM, was developed. Based on the short duration and long duration field testing a comparative study was prepared, to evaluate the effect of embedding PCM in the building envelope on the indoor thermal behavior of the building in the tropical climate of India. Additionally, the commercially available low cost PCM used in the experiment was thermally characterized to analyze the thermal energy storage parameters like thermal conductivity, latent heat storage parameters, thermal stability, thermal reliability, heating and cooling behavior, and leak proof performance. The thesis comprises of five chapters: Chapter 1- Introduction and background, Chapter-2 Literature review, Chapter 3- Method and materials, Chapter 4- Result and xxi discussion, and Chapter 5- Conclusion and recommendation for future work. Chapter 1 focuses on the need and concepts of thermal energy storage in buildings. A detailed discussion on the thermo-physical properties of PCM, methods of integrating the PCM in the building envelope, and principal of operation of PCM, when integrated in the building envelope was also done. In chapter 2, a detailed and robust literature review on indirect methods of integration of the PCM in the building envelope was conducted. Based on this literature review, a suitable method of integrating the PCM in the building was identified for experimentation work. Chapter 3 presents the methodology opted to conduct the experiments. This chapter also elaborates about the material used and experimental set up in detail. Chapter 4 presents the results of all the experiments and discusses about the parameters which affects the indoor thermal comfort of the building. Chapter 5 presents the concluding remarks and recommendation for future work. The scope of this study is to develop energy efficient building envelope by integrating the PCM with the building element. This study will be beneficial in improving the indoor thermal behavior of the building by using thermal energy storage technique through Phase Change Material. The improvement in the indoor thermal comfort will reduce the usage of electrical appliances and consequently results in energy savings.