Globally, energy standards for new buildings are being reinforced to improve energy efficiency, and remodeling policies are being promoted for old buildings. The South Korean Government is promoting green remodeling projects, and focusing on research and product development to improve the performance of old windows and curtain walls. In line with this, the present study proposes two remodeling methods using polymer dispersed liquid crystal (PDLC) films, which can adjust solar radiation for old office buildings. In addition, energy efficiency improvement and daylight performance according to remodeling were analyzed. Attaching PDLC films to the glass of old curtain walls was analyzed; this can reduce heating and cooling energy, reduce the annual discomfort glare occurrence rate, and increase the annual indoor appropriate illuminance ratio. Furthermore, producing a window by laminating a PDLC film between two sheets of glass and putting it over the existing curtain wall was also analyzed; this can reduce annual building energy consumption and the annual discomfort glare occurrence rate, and improve the annual indoor appropriate illuminance ratio. Therefore, PDLC film is expected to be applicable as a next-generation green remodeling material because using it in remodeling can improve energy efficiency of old office buildings and indoor daylight performance.

The objective of this paper is to analyze the control conditions of the transmittance rate, and determine the conditions that are most optimal with respect to building energy and daylight performance in three climate conditions: Riyadh, Saudi Arabia (hot climate); Inchon, South Korea (hot and cold climate); and Moscow, Russia (cold climate). The analysis was based on the electrochromic glass developed by a research team. Electrochromic glass is a next generation solar control glass that can control the transmittance of the glass itself. Therefore, proper control methods are essential for rational use of this electrochromic glass. To properly control electrochromic glass, daylight performance must be considered, along with building energy (heating, cooling, and lighting). If only building energy is considered, transmittance needs to be lowered during the summer season and increased during the winter season. Controlling electrochromic glass transmittance with such a method would not improve the satisfaction of users and occupants of a building due to the resulting glare. In addition to energy reduction, the basic function of solar control glass is to prevent glare. Therefore, in this study, we develop the Energy and Daylight Performance Index (EDPI) using, to evaluate the combined building energy and daylight performance and deduce the optimal control method for electrochromic glass. In addition, optimal control conditions for the three different climatic regions were obtained. Limitations of this study were that the scope was restricted to the eastern climate region, and that the building analysis model was limited to one climate region. It is expected that the optimal control method could be used as an initial database in the development of a electrochromic glass control system.

Electrochromic glass is anticipated as the next generation of solar control glass for construction because it can control the transmittance of the glass itself. This study analyzed building energy and light environment performance by applying electrochromic glass in triple glazing in order to verify both the solar control characteristics of electrochromic glass and its high insulation performance. This paper evaluates the performance of the electrochromic glass developed by our research team in Korea in five control conditions of varying temperatures and solar radiation levels. By analyzing the cooling and heating load, lighting energy, Daylight Glare Index (DGI), and interior illuminance when applying the selected conditions to office buildings, this paper discerns the optimal control conditions for electrochromic glass. To do so, the optical characteristic data of the electrochromic glass was analyzed via an experiment, and the creation of triple glazing for construction was conducted. The performance of electrochromic glass was evaluated by analyzing hourly and yearly data for cooling, heating load, and lighting energy during a typical day in summer and winter. From this analysis, the control condition with an outstanding performance from an energy perspective was identified. The performance of the light environment was assessed, and the EDPI overall evaluation index was used to find the electrochromic glass’ optimum control conditions for integrating energy and light environment.

Glass façade curtain walls in buildings is the façade system of choice in modern architecture of mid- to high-rise buildings. This study investigates the seismic and thermal insulation performance of curtain wall systems through structural analysis using the finite element method (FEM) and LBNL Window&Therm insulation analysis. The aim was to optimize the capability of the curtain wall module system and the fastener element technology to respond to displacement and vibration caused by dynamic seismic waves. Using the structural analysis of the optimization process, a curtain wall system capable of withstanding earthquake waves of 0.4 Hz, displacement of ±150 mm or more, and capable of responding to three-axis (X, Y, and Z-axis) dynamic earthquakes, was fabricated. Then, a curtain wall system that satisfies not only the evaluation of seismic performance, but also the desired airtightness, watertightness, wind pressure, and insulation, which are essential requirements for field applications, was verified through an experiment. Based on this study, it is expected that a curtain wall system capable of responding to three-axis dynamic seismic waves can be applied to mid- and high-rise buildings to prevent secondary damage in the event of an earthquake.

Windows are essential in buildings; however, they have poor thermal performance, so extensive research has been conducted on improving their performance. In this study, we developed vacuum-glazed windows with excellent insulation via the in-vacuum method, which shortens the manufacturing time and vacuuming degree considerably. In addition, the configuration of the pillars, low-emissivity (low-e) coating, and frame from a thermal performance perspective was experimentally optimized. The results revealed that the optimal pillar placement spacing is 40 mm and that the low-e coating surface must be located inside the vacuum layer to maximize insulation performance. The vacuum-glazed window produced by the in-vacuum method was applied to an actual residential building to investigate its thermal performance, which was compared with that of a triple-glazed window. The results showed that the center-of-glazing heat flow of the vacuum-glazed window was approximately 0.8 W/m²K lower than that of the triple-glazed window. The difference between the average indoor and outdoor surface temperatures during the nighttime was found to be up to 35.1 °C for the vacuum-glazed window and 23.1 °C for the triple-glazed window. Therefore, the energy efficiency of the building can be greatly improved by applying vacuum windows manufactured via the in-vacuum method and optimized for the best thermal performance.

Heated glass can be applied to improve windows’ condensation resistance and indoor thermal comfort in buildings. Although this applied technology has advantages, there are still some concerns in practical applications, such as additional energy consumption and control issues. This study evaluates the effectiveness of a heated window heating (HWH) system in terms of thermal comfort and heating energy performance (HEP). The simulation-based analysis is performed to evaluate the effectiveness of the HWH using a residential building model and to compare it with radiant floor heating (RFH) and hybrid heating (HH) systems (i.e., combined HWH and RFH). This study also investigates the peak and cumulative heating loads using HWH systems with various scenarios of control methods and setpoint temperature. The predicted mean vote (PMV) is used as an indoor thermal comfort index. The ratio of cumulative thermal comfort time to the entire heating period is calculated. The results show that HWH and HH can reduce the heating load by up to 65.60% and 50.95%, respectively, compared to RFH. In addition, the times of thermal comfort can be increased by 12.55% and 6.98% with HWH and HH, respectively. However, considering the social practices of South Korea, HH is more suitable than HWH. Further investigations for HH show that a surface setpoint of 26 °C is proper, considering both heating demands and thermal comfort. In addition, the setpoint temperature should be determined considering HEP and the thermal comfort for HWH, and the optimal setpoint temperature was suggested under specific conditions.