Phase change materials (PCMs) have been considered as an innovative technology that can reduce the peak loads and heating, ventilating and air conditioning (HVAC) energy consumption in buildings. Basically they are substances capable of storing or releasing thermal energy as latent heat. Because the amount of latent heat absorbed or released is much larger than the sensible heat, the application of PCMs in buildings has significant potential to reduce energy consumption. However, because each PCM has its own phase change temperature, which is the temperature at which latent heat is absorbed or released, it is important to use an appropriate PCM for the purpose of building envelope design. Therefore, this paper aims to investigate the energy saving potentials in buildings when various PCMs with different phase change temperatures are applied to a lightweight building envelope by analyzing the thermal load characteristics. As results, the annual heating load increased at every phase change temperature, but the peak heating load decreased by 3.19% with heptadecane (phase change temperature 21 °C), and the lowest indoor temperature increased by 0.86 °C with heptadecane (phase change temperature 21 °C). The annual cooling load decreased by 1.05% with dodecanol (phase change temperature 24 °C), the peak cooling load decreased by 1.30% with octadecane (phase change temperature 29 °C), and the highest indoor temperature dropped by 0.50 °C with octadecane (phase change temperature 29 °C). When the night ventilation was applied to the building HVAC system for better passive cooling performance, the annual cooling load decreased by 9.28% with dodecanol (phase change temperature 24 °C), the peak load decreased by 11.33% with octadecane (phase change temperature 29 °C), and the highest indoor temperature dropped by 0.85 °C with octadecane (phase change temperature 29 °C).

The electric power generation efficiency of photovoltaic (PV) panels depends on the solar irradiation flux and the operating temperature of the solar cell. To increase the power generation efficiency of a PV system, this study evaluated the feasibility of phase change materials (PCMs) to reduce the temperature rise of solar cells operating under the climate in Seoul, Korea. For this purpose, two PCMs with different phase change characteristics were prepared and the phase change temperatures and thermal conductivities were compared. The diurnal thermal behavior of PV panels with PCMs under the Seoul climate was evaluated using a 2-D transient thermal analysis program. This paper discusses the heat flow characteristics though the PV cell with PCMs and the effects of the PCM types and macro-packed PCM (MPPCM) methods on the operating temperatures under different weather conditions. Selection of the PCM type was more important than the MMPCM methods when PCMs were used to enhance the performance of PV panels and the mean operating temperature of PV cell and total heat flux from the surface could be reduced by increasing the heat transfer rate through the honeycomb grid steel container for PCMs. Considering the mean operating temperature reduction of 4 °C by PCM in this study, an efficiency improvement of approximately 2% can be estimated under the weather conditions of Seoul.

Buildings account for a significant portion of a nation’s total energy consumption. To meet the global demand for greater energy efficiency, many countries are drastically strengthening insulation regulations for buildings. Thus, dramatically thicker wall insulation may be required, which can adversely affect the value of a building by reducing its effective floor area. Hence, high-performance insulation materials, such as vacuum insulation panels (VIPs), are of interest in building design. In this study, external insulation systems using VIPs were examined to determine their effectiveness in high-performance insulation systems for high-rise apartment buildings. A variety of mechanically and adhesively fixed external insulation systems with various insulation layer compositions have been proposed as alternatives to conventional internal insulation systems. The performance of conventional insulation systems and the proposed alternatives were compared through three-dimensional heat transfer simulations. The construction costs and the ease of installation of the various systems were also compared. The overall performance of each alternative in terms of the insulation performance, construction costs, and ease of installation was thus evaluated to determine the most effective alternative.

1. INTRODUCTION: The emergence of environmental problems as major social issues throughout the world has prompted sustainable development efforts in a wide range of areas, including industry, construction, and transportation, followed by the execution of numerous studies and policies. The concept of sustainable development has been dealt with in earnest in the construction field since the Declaration of Interdependence for a Sustainable Future at the 18th Chicago Convention of UIA in 1993. This Declaration included tasks to be implemented with respect to green buildings, such as the recycling of resources, application of energy-efficient designs, and utilization of natural energy in addition to the application of sustainable designs. As part of green building practices, countries around the world have been implementing various green building certification standards, such as LEED, GBCC, CASBEE, and BREEAM. These certification standards prescribe the criteria relating to the external environment, energy conservation, materials and resources, and the indoor environment, with energy conservation being the top priority for each of these issues. This is due to energy consumption in building operation accounting for more than half of the building life cycle cost. Accordingly, although many studies are undertaken for the purpose of developing the means for conserving energy in relation to green buildings, the majority of these studies are concentrated on the development of technologies for environmental facilities through the application of active designs. study the finite nature, propose hypotheses, and gather their evidence. And, to date, there is little to suggest that copying nature purports any advantages to architects, primarily because fully autonomous buildings or towns have yet to be built. According to the described Malthusian-Darwinian dynamic, the two critical questions that we seek to address in this paper are: i) What is the essence of a sustainable dwelling? and ii) What principles should be adhered to in making a dwelling sustainable? In other words, this study aims to elucidate the essence of sustainability in green building design implementation.

To increase the heat capacity in lightweight construction materials, a phase change material (PCM) can be introduced to building elements. A thermally activated building system (TABS) with graphite/PCM concrete hollow core slab is suggested as an energy-efficient technology to shift and reduce the peak thermal load in buildings. An evaluation of heat storage and dissipation characteristics of TABS in graphite/PCM concrete has been conducted using dynamic simulations, but empirical validation is necessary to acceptably predict the thermal behavior of graphite/PCM concrete. This study aimed to validate the thermal behavior of graphite/PCM concrete through a three-dimensional transient heat transfer simulation. The simulation results were compared to experimental results from previous studies of concrete and graphite/PCM concrete. The overall thermal behavior for both materials was found to be similar to experiment results. Limitations in the simulation modeling, which included determination of the indoor heat transfer coefficient, assumption of constant thermal conductivity with temperature, and assumption of specimen homogeneity, led to slight differences between the measured and simulated results.