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In countries, such as Korea, where climate change is clear due to the four seasons, some of the collected energy must be released in the summer season, and these measures for heat dissipation fail to be very effective, thus causing system overload and defects frequently. In this study, we devised an overheating prevention system for the solar hot water and heating system using the variation of the shadow caused by the solar altitude angle that changes every hour, and for this purpose, a solar power generation module was placed over the solar collector. By using simulations, the system was designed in such a way that direct sunlight would be naturally blocked from reaching the solar collector due to the high solar altitude in the summer and that 100% of direct sunlight could reach the collector due to the low solar altitude in the winter. It was confirmed that the designed conditions were also satisfied in the actual test bed. In order to predict the performance of the system through simulations, the temperature of the solar thermal storage tank was calculated every hour after modifying the energy equation used in a previous study, and as a result of determining whether the system is overheated afterwards, it is expected that the degree of system overheating can be reduced. The shading did not affect the system efficiency in the season in which an actual heating and hot water load was needed.

Many countries adopt a time-of-use (TOU) rate system, in which electricity rates vary by season and time of day, to reduce power usage during peak power consumption hours. South Korea offers a TOU rate plan that depends on the electricity usage of a building and its contracted power; in this plan, the electricity rate reaches up to 300% depending on the time of day. Hence, electrically powered variable refrigerant flow (VRF) systems are increasingly being installed in small- and medium-sized buildings requiring individual cooling and heating operations. This study aims to develop a new control algorithm to reduce electricity consumption and electricity rates for cooling and heating by VRF systems in university buildings adopting the TOU rate plan and apply it to actual buildings to verify the reduction effect. The proposed control algorithm primarily consists of a module that controls the refrigerant evaporation temperature (cooling) and high pressure (heating) according to the indoor heat load and a module that controls the indoor set temperature based on the hourly electricity rate. The developed algorithm was installed in the controller of a VRF system installed in an actual university building and the annual effect was verified using the method proposed by the International Performance Measurement and Verification Protocol. As a result, power consumption was reduced by 17.8% for heating and 4.0% for cooling due to the application of the control algorithm, and the electricity rates reduced by 19.2% and 7.3%, respectively.

A variable refrigerant flow (VRF) system is convenient to install and manage as well as the operability via occupants is superior compared to a chiller system. Thus, the use of the VRF system has increased in East Asia and Europe in recent years. In particular, a water-cooled VRF system can solve a space problem of installation for outdoor units in existing air-cooled systems. Thus, it can be applicable to large-sized buildings. However, most cooling tower operations are done with the same setup regardless of the changes in outdoor conditions during the operating period, which is a conservative method for a water-cooled mode. The present study aims to improve the performance of outdoor units in the VRF by reducing the temperature of cooling water to a lower temperature than the existing setup value and verify this through actual measurements. To do this, a new algorithm for a cooling tower operation was developed and applied to a six-week operation during the summer to analyze the effect of the change in setup value. The result showed that power consumption of the cooling tower system and VRF outdoor unit was reduced by 24% and 5.9%, respectively due to the new setup and the coefficient of performance (COP) of the outdoor unit and system was improved by 7.3% and 12.7%, respectively thereby reducing an operation cost by 11%.

This study aims to compare a performance of Variable Refrigerant Flow (VRF) system with Roof Top Unit (RTU) variable-air-volume (VAV) system through field tests and energy simulations. The field test was conducted at the same conditions as much as possible between two systems such as the installation and operating environments of heating, ventilation and air conditioning (HVAC) system including internal heat gain and outdoor conditions including buildings to compare the performance of two systems accurately. A VRF system and RTU were installed at the test building located in Tennessee Oak Ridge in the USA and the same internal heat gain was generated at the same operating time of the two systems using lighting, electric heater, and humidifier inside the building. The HVAC system was alternately operated between cooling and heating operations to acquire energy performance data and compare energy usage. Furthermore, an hourly building energy simulation model was developed with regard to the VRF system and RTU and then the model was calibrated using actual measured data. Then, annual energy consumptions of the two systems were compared and analyzed using the calibrated model. Moreover, additional analysis was conducted also when the control of discharge air temperature in the RTU was changed. The field test result showed that when energy consumptions of two systems were compared at the same outdoor conditions using the weather-normalized model, the VRF system exhibited energy reduction by 17% during cooling operation and by 74% during heating operation approximately. A comparison on the annual energy consumption using simulations showed that the VRF system reduced more energy consumption than that of the RTU by 60%. When a discharge air temperature in the RTU was controlled according to an outdoor air temperature, energy consumption of RTU was reduced by 6% in cooling temperature and 18% in heating operation, respectively. As a result, energy consumption of the VRF system was reduced more than that of the RTU by 55% approximately.

In this study, a refrigerant evaporating temperature control algorithm was developed for the variable refrigerant flow (VRF) system, and its effect was quantitatively examined through a multi-calorimeter experiment and a field test in actual buildings. As previous studies on refrigerant evaporating temperature control have been predominantly conducted through experiments and simulation, aspects such as the impact of refrigerant evaporating temperature control on energy-saving and indoor temperature in an actual building and the change in the energy efficiency of the VRF system due to the Thermo on–off change of indoor units, have not been examined. As such, in this study, an algorithm that predicts the indoor load based on the indoor temperature change and controls the refrigerant evaporating temperature based on the load was developed. Before applying the developed algorithm to actual buildings, the effectiveness of refrigerant evaporating temperature control was evaluated through an experiment. Changes in the performance and efficiency of the VRF system according to the evaporating temperature and the number of operating indoor units were measured in a multi-calorimeter, and the effect of refrigerant evaporating temperature control on the reduction in the actual number of operating indoor units due to the Thermo off was examined under part-load conditions. In addition, the developed algorithm was applied to the office and education buildings in a factory located in Thai Nguyen city, Vietnam, and its energy-saving effect on the indoor temperatures was verified as per the energy effect verification process provided by the International performance measurement and verification protocol (IPMVP). The verification results confirmed that conducting refrigerant evaporating temperature control saves energy by increasing the Thermo on rate and the refrigerant evaporating temperature. It was additionally confirmed through the actual operation data that refrigerant evaporating temperature control has the effect of improving the indoor thermal environment by increasing the accuracy of indoor temperature control.

As one of the energy saving policies, the Korean government has been regulating the indoor thermal environment of public office facilities in Korea, starting with energy conservation measures in 1980. This policy, which is above 28 &deg, C in summer and below 18 &deg, C in winter, is causing discomfort among the occupants. The purpose of this study is to support the need to improve temperature limitation standards of the Korean public office facilities. For this purpose, the standards for the thermal environment in offices of major countries and associations were examined. Subsequently, they were compared with the Korean standards. Additionally, nine buildings of public office facilities in Korea were surveyed on the thermal environment, and PMV measurement was carried out. As a result, most of the buildings that complied with the cooling temperature standard as well as most of the buildings that did not comply were found to be uncomfortable. In conclusion, to improve the comfort of Korean public office facilities in the heating and cooling period, it is necessary to mitigate temperature regulation and regulate additional environmental factors.

Since the massive power outages that hit across the nation in September 2011, a growing imbalance between energy supply and demand has led to a severe backup power shortage. To overcome the energy crisis which is annually repeated, a policy change for deriving energy supply from renewable energy sources and a demand reduction strategy has become essential. Buildings account for 18% of total energy consumption and have great potential for energy efficiency improvements; it is an area considered to be a highly effective target for reducing energy demand by improving buildings’ energy efficiency. In this regard, retrofitting buildings to promoting environmental conservation and energy reduction through the reuse of existing buildings can be very effective and essential for reducing maintenance costs and increasing economic output through energy savings. In this study, we compared the energy reduction efficiency of national power energy consumption by unit production volume based on thermal power generation, renewable energy power generation, and initial and operating costs for a building retrofit. The unit production was found to be 13,181GWh/trillion won for bituminous coal-fired power generation, and 5,395GWh/trillion won for LNG power generation, implying that LNG power generation seemed to be disadvantageous in terms of unit production compared to bituminous coal-fired power generation, which was attributable to a difference in unit production price. The unit production from green retrofitting increased to 38,121GWh/trillion won due to the reduced energy consumption and benefits of greenhouse gas reduction costs. Renewable energy producing no greenhouse gas emissions during power generation and showed the highest unit production of 75,638GWh/trillion won, about 5.74 times more effective than bituminous coal-fired power generation.

This paper investigates the indoor light environment, lighting energy consumption and total energy including annual HVAC system in temperate and temperate monsoon climate zones. In certain areas, a...

The additional process of load calculation during the retrofit of heating, ventilation, and air conditioning (HVAC) equipment has been generally omitted in Korea, in recent years. Instead, a simple replacement of HVAC equipment, based on existing HVAC capacities, has been used, which is limited when taking the variation of internal heat gain into consideration, due to changes in the consumption power due to light and office automation (OA) equipment in recent years. Thus, this study aimed to identify a change in internal heat gains over 30 years, from 1985 to 2015, study investigated actual measurement-based academic papers and catalogs about OA equipment, lighting, and the number of occupants per unit area. The heat load produced from OA equipment has increased by approximately 49.6% in 2015 compared to that of 1980, and the heat load from lighting equipment has decreased by 47% compared to that of fluorescent-based lighting, and the heat load from human bodies was approximately 10 W/m2 on average, which showed a minimal change over the past 30 years. The internal heat gain calculated for 30,000 m2 of total floor area has increased constantly for the last 30 years. Note that the internal heat gains were designed excessively, as the values used in literature was approximately 17% to 50% smaller than the value used normally in the case of pre-2000 designs, and the values used after 2000 were approximately 35% to 50% smaller than the design standard value.

The dynamic pricing of electricity, where the electricity rate increases in a time zone with a high demand for electricity is typically applied to a building whose power reception capacity is greater than a certain size. This includes the time of use(TOU) electricity pricing in Korea which can induce the effect of reducing the power demand of a building. Meanwhile, a VRF (Variable Refrigerant Flow) system that uses electricity is regarded as one of the typical heating and cooling systems along with central air conditioning (central HVAC) for its easy operation and application to the building. Thus, to reduce power energy and operating costs of a building in which the TOU and VRF systems are applied simultaneously, we suggested a control for changing the indoor temperature setting within the thermal comfort range or limiting the rotational speed of an inverter compressor. In this study, to describe the features of the above-mentioned control and verify its effects, we evaluated the results obtained from the analysis of its operation data. Through the actual measurements in winter operations for 73 days since mid- December 2014, we confirmed a reduction of 10.9% in power energy consumption and 12.2% in operating costs by the new control. Also, a reduction of 13.3% in power energy consumption was identified through a regression analysis.

In a general building retrofit process, the reinforcement of insulation performance or air-tightness in walls and windows are conducted to reduce the maximum cooling and heating load of buildings. A heat source consists of heat-source equipment and water-pipe systems, which are replaced with high-efficient specification materials. Most of them are simply replaced with the same capacity as the previous heating equipment. This study aims to investigate matters required for decision making in a retrofit plan, such as conducting an investigation of the maximum load reduction in buildings obtained by the retrofit and the capacity of heat-source equipment that reflects the reduction, and the re-use or replacement of the water-pipe system, etc. in advance. This study verified that when the capacity of heat-source equipment was reduced, the pipe diameter of the water-pipe system was also decreased, but if existing pipes were re-used, the transportation power of the pump was reduced due to the reduction in flow velocity. The changes in maximum cooling and heating load through retrofit were quantitatively verified compared to that of the initial design of the building based on previous study results, and flow rates of cool and hot water were determined by re-calculating the capacity of the heat-source equipment. Using the results, the water-pipe system was re-designed, and the annual transportation power of the pump was calculated through simulations. The calculation results verified that the transportation power decreased by up to approximately 10% when oversized pipes were re-used from the existing water-pipe system. Additionally, when the capacity of the heat-source equipment was decreased, reasonable measures considering remodeling, construction duration, and cost were derived.

This study looks into changing building energy use by application of phase change material (PCM). PCM does not need extra energy for operation and is used for reducing building energy use and, CO2 output by displaying semi-permanent effects after installation. It also is able to avoid the maximum electric power time-zone by inducing a time lag phenomenon of cooling and heating loads with high thermal capacity using latent heat. To verify the efficiency of blinds and PCM, tests about the PCM operation mechanism using air conditioning machinery and nocturnal panel cooling were done. In the test results of the case using PCM installation, a blind angle with machinery air conditioning and nocturnal panel cooling at the same time shows a 22 percent energy saving effect against general space. The test results of each case were compared and analyzed based on the blind and window opening settings. Finally, the energy reduction of existing buildings using PCM application was reviewed based on the final measurement results.

Many nations are developing temporary residence to be used in case of residence damage owing to natural disasters. This study is to compensate planning and operational defects of national temporary residences and to suggest a Prototype plan that meets the characteristics of temporary residence. Thus, a research on the actual condition of national temporary residences was conducted and problems were derived based on results. The spatial performance of temporary residences based on the minimum residence standard was reflected and construction methods that satisfy characteristics of temporary residences were considered so as to plan Korean-type temporary residences that maximize extendibility and variability.

The artillery fire accident in Yeonpyeong Island showed that the man-made disaster caused by the domestic political conditions as well as the conventional natural disaster can occur in Korea. Especially, it can be known that the whole community can be abandoned despite of a small scale of practical damage in residential district and the resulting large scale of refugees can be produced in the nation. This study investigated the real condition of temporary housing which has been provided at the Island. Firstly, in the theoretical review based on the literature study, the content on the background of temporary housing, the providing procedure of its concept, the status of supply, etc. has been considered. And it researched the current condition of the entire temporary housing through the questionnaire and interviews targeting the residents in the Island. So it purposed to make use of the results as a plan and design for future temporary housing against disaster.

This paper will focus on the energy performance evaluation of a cooling plant system in a semiconductor factory. Several energy saving technologies namely: integrated cooling towers, free cooling systems, control of the chilled water quantity, etc., have been adopted to improve efficiency of the cooling plant system. We have collected actual operating data for 2 years and evaluated the performance of chillers’ COP and the whole cooling plant system's COP and they showed satisfactory results even if the thermal load of the factory was about half compared with design phase assumption. We also have verified each effect of the energy saving technologies through model-based simulation analysis. The annual electric power consumption dropped about 35% compared to conventional cooling plant systems in case of design phase thermal load. And the faulty status operation of the chiller's number control miss occurred while we monitored. Electric power consumption increased about 17% compared to normal status operation at the same period.

There are many reports about faulty status in building air-conditioning systems recently. It becomes difficult to keep indoor air temperature appropriately as faults occur, and the faults cause waste of building energy consumption. The model-based fault detection and diagnosis (FDD) methods have been researched for specific parts of air-conditioning system such as chillers, coils, variable air volume units (VAV units), etc. It needs, however, much time and labor to monitor and check every single part because we cannot predict where and when the faults occur. The purpose of this study is to examine indoor air temperature changes and energy consumption increase when faults occur and to develop an easy-to-use FDD tool that helps to find out the faulty place through the whole building air-conditioning system. And then, we treat the reliability of the proposed FDD tool and effectiveness to control of indoor environment deterioration and energy consumption increase by the tool is evaluated based on building air-conditioning system simulation in this paper.

This paper treats energy and cost performance of a cooling source system with indirect seawater utilization for air conditioning in a commercial complex. Seawater utilization has merits as a cooling source, because seawater temperature is lower than outdoor air in summer and it is cost effective because there is no water monetary cost. Actual operating data has been measured for about 2 years and the chiller and system co-efficient of performance (COP) have indicated about 4.77 and 2.93, respectively, even in summer season and the mean efficiency of the thermal storage system was about 89.9% taking into account heat loss of pumps. In addition, we have constructed simulation models for cooling tower systems, air cooling chiller systems and direct seawater utilization systems then compared them to this system. The electric power consumption of the indirect seawater utilization system was almost the same as the other systems except the air cooling chiller system, because using lower seawater temperature made the chiller efficiency higher. In conclusion, our results showed the indirect seawater utilization system was able to improve the system COP compared to air cooling chiller system, and cancel water consumption compared with the cooling tower system, and cut down an initial and maintenance costs compared with the direct seawater utilization system.

The purpose of this paper is to clarify energy performance of the cooling plant system in the industrial building using actual measured operating data and numerical simulation analysis. One aspect of industrial buildings is that they have large energy consumption for manufacturing and air-conditioning compared with office and commercial buildings. Some examples of high-efficiency technologies installed in this particular cooling plant system are inverter chillers, integrated cooling towers and a free-cooling system. The inverter chiller which has been put on the market recently is state-of-the-art technology. The maximum COP of the inverter chiller reaches about 18 under certain conditions and integrated cooling towers make lower temperature cooling water as the whole capacity is large. Actual operating data indicates satisfied values for chiller and system COP during the running period and the simulation results show that the cooling plant system can cut down annual electric power consumption by about 48% compared with conventional cooling system.