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The installation and operation of geothermal systems increased due to the expectation of good cooling and heating performance due to stable heat source temperatures. In actual geothermal system operations, heat source temperature rises or falls due to an imbalance of heating and cooling energy usage. Problems of source side temperature result in reduced geothermal system performance. The purpose of this study is to develop hybrid geothermal system operation technology to stabilize temperature and improve system performance by utilizing auxiliary heat source system. The auxiliary heat source system is operated by comparing the performance when operating the geothermal heat pump system alone and the performance when operating the hybrid geothermal heat pump system. The performance of a hybrid geothermal system is determined by the circulating water temperature of the geothermal system and the circulating water temperature of the auxiliary heat source system. Hybrid geothermal heat pump system performance is predicted through numerical analysis and collection of hybrid geothermal system performance data at various temperature ranges through field test. An operating method was developed using the predicted performance as the changeover operating point of the hybrid geothermal heat pump system. When applying the development and operation technology, it handled about 11% more load than the existing geothermal system operation. The addition of an auxiliary heat source increases the initial investment cost compared to the existing geothermal system, but decreases energy consumption, confirming that the initial investment cost of 15.3 years is recovered.

In South Korea, the evaluation criteria for installing shading devices are defined by regulations, but the standards of design methods are not clearly established. The installation of shading devices has become mandatory for some public buildings due to revised regulations. Therefore, a design of horizontal shading device is required, and indoor environmental problems which may occur due to their installation should also be taken into consideration. This research aimed to propose a design which takes into account the energy consumption which may occur if the horizontal shading device is installed and suggests an improved design method of horizontal shading devices when they are installed. Consequently, it was confirmed that as the protrusion of the horizontal shading device becomes longer, the incoming daylight is reduced and the indoor intensity of illumination becomes lower, and thus more lighting energy may be consumed in a room where the shading device is installed than in the one where it is not. Therefore, annual energy consumption was calculated by applying the lighting control and it was found that the total energy consumption decreased by the reduction of air-conditioning and fans and lighting energy consumption.

The objective of this study was to propose a control method with a ventilation requirement of variable air volume (VAV) system in multi-zone. In order to control the VAV system inmulti-zone, it is essential to control the terminal unit installed in each zone. A VAV terminal unit with conventional control method using a fixed minimum air flow can cause indoor air quality (IAQ) issues depending on the variation in the number of occupants. This research proposes a control method with a ventilation requirement of the VAV terminal unit and AHU inmulti-zone. The integrated control method with an air flow increase model in the VAV terminal unit, AHU, and outdoor air intake rate increase model in the AHU was based on the indoor CO2 concentration. The conventional and proposed control algorithms were compared through a TRNSYS simulation program. The proposed VAV terminal unit control method satisfies all the conditions of indoor temperature, IAQ, and stratification. An energy comparison with the conventional control method showed that the method satisfies not only the indoor thermal comfort, IAQ, and stratification issue, but also reduces the energy consumption.

Considerable efforts have been made to reduce the energy consumption of buildings due to the energy crisis, and, the Korean government has supported the use of renewable energy through various grants. Among the possible renewable energy sources, geothermal energy can be used regardless of the outside weather. Therefore, energy consumption can be reduced considerably in summer and winter. Despite the increasing use of renewable energy, the use of renewables has not been operating appropriately. Therefore, this study examined some of the problems of the operation of renewable energy and some possible improvements. The aim of the study is to evaluate a building containing an actual installed multi-geothermal heat pump (Multi-GHP) system, in terms of the energy efficiency. In addition, this study evaluated the present control system and the method of complex operation regarding existing heat sources systems and GHP systems through a simulation. The results can be regarded as the result of a hybrid operation method for the improvement of an existing operation. Therefore, the Multi-GHP system energy use of a hybrid operation condition of the Multi-GHP systems and the absorption (ABS) chiller-heater system was reduced compared to the operation condition of the Multi-GHP system, and the total energy consumption of the heat source equipment was reduced. The proposed operation plan was evaluated after applying the system to a building. These results showed that the efficient operation of a Multi-GHP hybrid operation method is possible. As a result, the GHP energy use of Multi-GHP systems and the ABS chiller-heater system was reduced by 30% compared to existing operation and the total energy consumption of heat source equipment was reduced by 78%.

ECO2 (building energy efficiency rating program) and passive energy conservation measures (ECMs) were established as a basic study for targeted methodologies and decision support systems development in Korea to meet national regulations. The primary energy consumption and economic evaluation of nonresidential buildings was performed. Passive ECMs were classified as planning and performance elements. The planning elements are the window-to-wall ratio (WWR) and horizontal shading angle. The performance elements are the thermal transmittance (U-value) of the walls, roof, and floor and the U-value and solar heat gain coefficient (SHGC) of windows. This study focused on the window-to-wall ratio and the U-value and solar heat gain coefficient of windows. An economic efficiency database for the constructed alternatives was built; the target building was set and the Passive ECM List for the target building was derived. The energy consumption evaluation and economic evaluation were performed for each of the constructed alternatives, and a methodology for guiding energy efficiency decisions was proposed based on the performance evaluation results, and the optimal Passive ECM List for the target building was derived.

Recently, the window area ratio of buildings has increased but the thermal insulation performance of windows is lower than the wall. Therefore, many studies have been carried out to reduce this heat loss. The Republic of Korea policies and guidelines for windows do not consider the optical and design elements of windows because it is more important to the insulation performance of windows. This paper proposes the supplement point of the Korea's policies and guidelines regarding windows through a comparison of Korea's policies and guidelines for windows, checks the variation of the energy consumption of buildings through the variation of the window elements, and proposes an energy analysis indicator for the Republic of Korea's situation. This study confirmed that the variation of the window elements affect to energy consumption by previous studies to consider in window design according to the policies and guidelines. The window elements were divided into performance elements of the windows and architectural/equipment plan element. By analyzing the energy consumption by changing the element, this study confirmed the variation of energy consumption by using the COMFEN4.0 simulation tool. This paper proposes an actual energy analysis indicator in the Republic of Korea.

The objective of this study was proposed a control method for the minimum air flow rate of a VAV terminal unit at an office building. The minimum air flow rate of the VAV terminal unit is the key factor affecting the thermal comfort, indoor air quality (IAQ), stratification and energy consumption, depending on the operating mode of the VAV system. Therefore, selecting the proper minimum air flow is very important. In this study, an algorithm was proposed considering the IAQ and stratification. The vertical air temperature was analyzed to find the supply air temperature that did not cause stratification. The integrated control algorithm with an air flow increase model in the VAV terminal unit and outdoor air intake rate increase model in the AHU was developed by comparing the energy consumption. Finally, the existing and proposed control algorithms were compared through a simulation. The proposed method was found to be more effective than the existing control method. The proposed VAV terminal unit control method satisfies all the conditions of indoor thermal comfort, IAQ and stratification issue. As a result of the energy comparison with the existing control method, the method satisfies not only the indoor thermal comfort, IAQ and stratification issue, but also reduces the energy consumption.

Terminal boxes are critical components of variable air volume (VAV) systems. The minimum airflow of terminal boxes is a key factor for comfort, indoor air quality (IAQ) and energy cost. If the minimum airflow is higher than needed, terminal boxes will have significantly more simultaneous heating and cooling, and airhandling units (AHUs) will consume more fan power. Buildings will have IAQ problems if the minimum airflow is less than required. A dynamic building simulation and field experiment were carried out to evaluate the impact of minimum airflow on the energy consumption of single duct VAV terminal boxes. A comparison of the simulation data with the existing constant setpoint revealed 20% annual energy savings in the improved minimum airflow setpoint. The experiment showed that the room air temperature can be maintained stably and the vertical difference in the room air temperature is lower than the comfort value when the improved minimum airflow setpoint is applied. Measurements of the CO 2 levels also revealed no indoor air quality problems.

Common energy management control systems (EMCS) in building HVAC systems could be made much more energy efficient without sacrificing comfort. Most researchers have focused on implementing optimal control algorithms in Variable Air Volume (VAV) systems with EMC functions. Previous studies have paid little attention to using terminal box EMC functions integrated with main AHU (Air Handling Unit) systems. Terminal boxes with EMCS may cause occupant discomfort and waste excessive energy if they do not have the proper operation control functions. The objective of this study is to evaluate the impact of energy consumption and estimate building energy savings on the optimal minimum air flow of single duct VAV terminal boxes and develop applicable optimal terminal box control algorithms for EMCS. This paper presents a dynamic model of a VAV terminal box with hydronic reheat, develops optimal terminal box control algorithms and applies the developed EMCS algorithms to an actual building. The results of this study show that optimal terminal box control algorithms can stably maintain the set room air temperature and reduce energy consumption for varying heating loads compared to conventional control algorithms.

The minimum airflow of VAV terminal boxes is a key factor for comfort, indoor air quality(IAQ) and energy cost. If the minimum airflow is not reasonable, it would waste energy and make IAQ problems. There are two types of VAV terminal box control logic. One is the single maximum, another is the dual maximum control logic. Dual maximum control logic is more efficiency way to reduce the energy consumption. It has a minimum airflow set point and a heating maximum set point. It allows the minimum airflow set point to be much lower than single maximum control logic. A building simulation was conducted to evaluate the energy consumption and the IAQ according to the control logic of the V AV terminal box. In the simulation, dual maximum control logic can save the energy up to 6.5% compared to the single maximum control logic.

Achieving energy efficiency by improving the operating method of the system used in existing buildings is attracting considerable attention. The Building Design Criteria for Energy Saving was established to induce energy saving design in the domestic construction field, and the introduction of a free-cooling system, such as an economizer system, as an item of the mechanical sector, was evaluated. The economizer is an energy saving method that reduces the building load by introducing outdoor air through damper control according to the indoor and outdoor conditions. The system consists of dry-bulb temperature control and enthalpy control and the mixed air temperature is kept constant in the conventional economizer controls. On the other hand, in dry-bulb temperature control, when the set value of the mixed air temperature is changed according to the load, additional energy savings are expected compared to the conventional control method. Therefore, this paper proposes an economizer control that makes the mixed air temperature variable according to the load in a Constant Air Volume single duct system. For this, a load prediction is needed and an Artificial Neural Network is used for the load prediction. In addition, the relationship between the mixed air temperature and energy were analyzed using the BIN method and TRNSYS 17. Based on the results of previous analysis, a control method which predicting the load using Artificial Neural Network and controlling the mixed air temperature according to the predicted load in the dry-bulb temperature control of a Constant Air Volume single duct system is proposed and the proposed control was applied to the dynamic simulation program and compared with the conventional control. The results show that the temperature of each room was 21&ndash, 23 &deg, C in summer and 22.5&ndash, 26 &deg, C in winter when the economizer was controlled using the proposed control method and the energy consumption analysis showed that 19% of the energy was reduced compared to the conventional method when the proposed method was controlled.

Terminal boxes are one of the major building HVAC components and directly impact building room comfort and energy costs. Current terminal boxes may cause occupant discomfort and waste energy if they have inappropriate operation control functions. The objective of this study is to develop and implement applicable terminal box control algorithms. The thermal conditions and energy consumption are compared between conventional and improved control algorithms using measured data. The results of this study show that improved terminal box control algorithms can stably maintain the room air temperature and reduce energy consumption compared to conventional control algorithms.

Terminal boxes maintain room temperature by modulating supply air temperature and airflow in building heating, ventilation and air-conditioning (HVAC) systems. Terminal boxes with conventional control sequences often supply inadequate airflow to a conditioned space, resulting in occupant discomfort, or provide excessive airflow that wastes significant reheat energy. In this study, the procedure for the optimal minimum airflow setpoint was developed to improve thermal comfort and reduce energy consumption. The determined minimum airflow setpoint was applied in an office building air-conditioning system. Improvements in indoor thermal comfort and energy reduction were verified through measurement. The results show that the minimum airflow reset can stably maintain room temperature, satisfy comfort standards and reduce energy consumption compared with the conventional control. Copyright © 2009 John Wiley & Sons, Ltd.

The construction industry has made considerable energy-saving efforts in buildings, and studies of energy-savings are ongoing. Shading is used to control the solar radiation transferred through windows. Many studies have examined the position and type of shading in different countries, but few have investigated the effects of shading installation in Korea. In this study, the case of the shading installation according to the standard of Korea, and variations of the heating and cooling load in the unit area on the performance of the windows were examined. This study compared the variations of the heating and cooling load in the case of horizontal shading and the changing position of venetian blinds. This study confirmed that horizontal shading longer than the standard length in Korea saved a maximum of 13% energy consumption. This study confirmed the point of change of energy consumption by the Solar Heat Gain Coefficient (SHGC) variations. The exterior venetian blinds and those between glazing were unaffected by the SHGC. On the other hand, in the case of a south façade, the interior venetian blinds resulted in 24% higher energy consumption than the installation of horizontal shading in case of Window to Wall Ratio (WWR): 80%, U-value: 2.1 and SHGC: 0.4.

Terminal boxes are the critical component of the VAV systems. The minimum airflow of terminal boxes is a key factor for comfort, indoor air quality (IAQ) and energy cost. If the minimum airflow is higher than required, terminal boxes will have significantly more simultaneous heating and cooling, and AHUs will consume more fan power. Buildings will have IAQ problems if the minimum airflow is less than required. A building simulation was conducted to evaluate the impact of energy consumption on the minimum airflow of single duct VAV terminal boxes. The results show that simulation data revealed that compared with the existing set point, the improved optimal minimum airflow set point exhibited an annual energy savings of 29%.Copyright © 2010 by ASME

Terminal boxes are one of the major building HVAC components and directly impact building room comfort and energy costs. Current terminal boxes may cause occupant discomfort and waste energy if they have inappropriate operation control functions. The objective of this study is to develop and implement applicable optimal terminal box control algorithms. The thermal conditions and energy consumption are compared between conventional and improved control algorithms using measured data. The results of this study show that optimal terminal box control algorithms can stably maintain the set room air temperature and reduce energy consumption compared to conventional control algorithms.Copyright © 2008 by ASME

Terminal boxes control space conditions in variable air volume (VAV) air-handling unit (AHU) systems. Terminal boxes either modulate airflow with a control damper or adjust discharge air temperature with a reheat coil. Terminal boxes will have a significant amount of simultaneous heating and cooling and AHUs will consume more fan power if the minimum airflow is higher than required. On the other hand, conditioned space will have indoor air quality (IAQ) problems with less air circulation if the minimum airflow is less than required. The objective of this study is to optimize the minimum airflow ratio to improve thermal environment and save energy consumption. In this study, the problem of current fixed minimum airflow ratio of terminal box is analyzed and variable minimum airflow ratio as an alternative is suggested. The results of this study show that variable minimum airflow ratio can stably maintain the set room air temperature and reduce energy consumption for varying heating loads compared to the conventional fixed minimum airflow ratio.Copyright © 2007 by ASME