Accounting for more than half of buildings in South Korea, the energy consumed by residential buildings has become a main concern and the cooing demand has rapidly increased. To reduce energy consumption, several passive and active design strategies have generally been applied. However, there has been an increasing demand for high window-to-wall ratios in residential buildings, it is imperative to block sunlight into a building effectively. Focusing on the reduction of cooling energy consumption in a residential building, the present study assessed the daylight and energy performance of shading devices. Among various types of shading devices, the Venetian blind, horizontal louver, light shelf, and egg-crate were selected. The illuminance levels in three different areas in a building were measured. In addition, the annual cooling energy consumption by these shading devices was investigated. As a result, both daylight and energy performance varied with different design options of these shading devices. Because of the slight performance difference among shading devices, the artificial loads of two best shading devices were compared. In sum, the egg-crate shading was the most proper shading device to block sunlight as well as reduce the cooling energy consumption effectively.

As one of the main businesses in Jeju-do in South Korea, specialized local products are grown in greenhouses. For greenhouse farming, it is preferable to use geothermal heat pump systems for energy conservation because of the stable temperature of the ground. In the same manner, heat pumps using underground air is recommended for greenhouse farming since underground air can easily be obtained from porous volcanic rocks in Jeju-do. However, direct usage of the underground air is not feasible for planting in the greenhouse or livestock care because the underground air is relatively humid and its temperature is low. For the present study, the heating performance of an air-to-water heat pump which used underground air as a heat source for greenhouse farming during the winter was assessed through measurements. In addition, the economic impact of the air-to-water heat pump (AWHP) was compared with a conventional air heater. According to the results, an AWHP can save more than 70% of the total heating costs compared with a conventional air heater. In sum, the utilization of the air-to-water heat pump using underground air can have a positive impact on reducing energy consumption as well as provide direct economic benefits.

Removing heat from high-density information technology (IT) equipment is essential for data centers. Maintaining the proper operating environment for IT equipment can be expensive. Rising energy cost and energy consumption has prompted data centers to consider hot aisle and cold aisle containment strategies, which can improve the energy efficiency and maintain the recommended level of inlet air temperature to IT equipment. It can also resolve hot spots in traditional uncontained data centers to some degree. This study analyzes the IT environment of the hot aisle containment (HAC) system, which has been considered an essential solution for high-density data centers. The thermal performance was analyzed for an IT server room with HAC in a reference data center. Computational fluid dynamics analysis was conducted to compare the operating performances of the cooling air distribution systems applied to the raised and hard floors and to examine the difference in the IT environment between the server rooms. Regarding operating conditions, the thermal performances in a state wherein the cooling system operated normally and another wherein one unit had failed were compared. The thermal performance of each alternative was evaluated by comparing the temperature distribution, airflow distribution, inlet air temperatures of the server racks, and recirculation ratio from the outlet to the inlet. In conclusion, the HAC system with a raised floor has higher cooling efficiency than that with a hard floor. The HAC with a raised floor over a hard floor can improve the air distribution efficiency by 28%. This corresponds to 40% reduction in the recirculation ratio for more than 20% of the normal cooling conditions. The main contribution of this paper is that it realistically implements the effectiveness of the existing theoretical comparison of the HAC system by developing an accurate numerical model of a data center with a high-density fifth-generation (5G) environment and applying the operating conditions.

Indoor thermal conditions can be highly influenced through building envelopes by outdoor conditions, especially climatic parameters. While a lot of attention has been paid to the thermal performance in core zones in buildings, other zones, such as perimeters, experience significant heat loss and gain through building envelopes. Focusing on the energy and thermal performance in perimeter zones, the present study performed an energy simulation to find the most susceptible building orientation in an office building in South Korea regarding the cooling loads during the summer. Through field measurements, the solar radiation impact on the thermal performance in the perimeter zones was practically investigated. To reduce the cooling loads in the perimeter zones, an air barrier system was utilized. As a result, the biggest amount of heat was observed in the perimeter zones facing the west façade in the winter, according to the measurements. While the highest temperature was observed at the internal surface of the windows, the temperature in the perimeter and core zones was stably maintained. The heat that occurred through the west façade was reduced by the air barrier system by removing the vertical thermal stratification using the fan-powered unit in the system.

Building insulation materials has a significant impact on building energy consumptions. However, conventional materials are easily flammable and can cause fire disasters in buildings. Therefore, it is important to select appropriate insulation materials for building energy efficiency and safety and Vacuum Insulation Panels (VIPs) are increasingly applied to building insulation. Considering this, the present study investigates energy performance of VIPs with design alternatives, such as window systems, infiltration rates, etc., by using energy simulation. Among various VIPs, fumes silica VIPs were chosen. In addition, eight combinations were compared to find the best energy efficient design conditions. The results of the present study showed that building energy performance can be improved with an appropriate combination of design options including fumed silica VIPs.

Most perimeter zones are thermally susceptible to the variation of outdoor conditions, especially due to a large amount of heat gain through glazing. To reduce heat gain, spandrel panels are generally installed in curtain walls of commercial buildings. For the present study, thermal performance in an office located in the perimeter zone was investigated using Computational Fluid Dynamics (CFD) simulation. By varying the spandrel panel heights, thermal comfort was assessed quantitatively. The findings suggest that when the spandrel panel height was 0 m, the highest temperature was observed in all cases. As the height of the spandrel panel was increased, the temperature decreased. For thermal comfort evaluation, Predicted Mean Vote (PMV) values at 1.5 m from the floor in all cases were larger than zero. PMV values in all cases were within the range of slightly cool to warm. When the spandrel panel height was 0 m, the highest thermal sensation (warm) among the cases was observed, which may cause thermal dissatisfaction for occupants. In addition, thermal comfort was deemed satisfactory based on the criteria of ASHRAE standard 55, when the height of the spandrel panel was higher than 0.6 m.