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The airtightness of a building has a significant impact on energy savings, structural longevity, and indoor air quality for occupants. Therefore, it is essential to accurately measure the airtightness of buildings, though the widely used fan pressurization method suffers from several shortcomings. For this reason, transient methods have recently emerged to assess airtightness by monitoring pressure changes over time, but studies using transient methods in this field are rare. In this study, we selected three representative buildings to conduct field tests to verify the practical applicability of the improved transient method. To verify the results of the transient method, we conducted a comparison experiment with the blower door test: a widely used measurement method. When measuring the effective leakage area, the average standard deviation of the transient method was 0.903 cm2, which was much smaller than the blower door test result of 1.488 cm2. In addition, the recorded standard errors ranged from 0.197 cm2 to 0.816 cm2 for the transient method and from 0.269 cm2 to 1.801 cm2 for the blower door test. Notably, the transitional method was more reproducible than the blower door test while showing similar accuracy. Given these results, it is expected that the improved transitional method can be used to evaluate airtightness performance in the field. [ABSTRACT FROM AUTHOR]

Energy savings from energy efficiency improvements are necessary to achieve energy savings and carbon neutrality goals in buildings. Additional energy savings can be achieved by strengthening building design standards. However, in Vietnam, standards have not been disaggregated despite the diversity of climatic conditions in each region. Therefore, disaggregating standards according to climatic characteristics and applying appropriate technologies can lead to cost-effective energy efficiency improvements. Therefore, this study analyzed Vietnam's climate characteristics and legal standards to propose energy-saving technologies suitable for Vietnam's climate. In order to explore energy-saving technologies suitable for the climate, regional meteorological data of Vietnam and South Korea were analyzed, and in order to propose energy-saving technologies considering climate characteristics and evaluate the efficiency of the technologies, the energy-saving potential was analyzed for four applications in the capital city of Hanoi. Based on the analysis results, the proposed insulation standards were well adapted to local conditions, and the study was able to verify the optimal energy-saving technologies according to climate conditions. These findings can be used as a basis for establishing regional standards for passive technologies in the future. [ABSTRACT FROM AUTHOR]

Highlights: [•] We measured the thermal performance of different window systems. [•] We also analyzed their effects on building energy savings in S. Korea. [•] The maximum ratings of the southern region and Jeju Island are Ratings 1. [•] The maximum ratings of the central region is just Ratings 2. [•] We suggest more specific and local criteria of the certification system. [ABSTRACT FROM AUTHOR]

Abstract: Microalgae have garnered interest for the production of valuable molecules ranging from therapeutic proteins to biofuels. However, microalgae also are associated with the considerable problem of phytoplankton bloom. In this study, we demonstrated algal growth using Isochrysis galbana as a model can be controlled photobiologically. Long dark period (24-h light: 24-h dark) unlike common photoperiod resulted in biomass loss and slower growth rates, but were unlikely to cause fatal damage. Algal cell growth can be significantly recovered with the onset of light. Also, it was confirmed that blue light-emitting diode (LED) illumination was able to effectively support cell growth of I. galbana as the sole light source. The blue LED intensity with 200% (580 l×, 18.52 μmol m−2 s−1) based on 8000 l× (98.4 μmol m−2 s−1) fluorescent lamp provided the best support for growth of I. galbana. We verified excessive light intensities lead to inhibition of algal growth, whereas low light intensities also did not promote algal growth. Further, I. galbana cell growth can be controlled using blue LED with extremely high LED intensities. These results may provide means to control algal population for either goal of growth or inhibition through proper use of such illumination. [Copyright &y& Elsevier]

Abstract: Blue light has outstanding transmission characteristics in the sea, and is known to cause the most sensitive visual response in common squid Todarodes pacificus. Application of a light emitting diode (LED) that can efficiently emit monochromatic light is expected to bring enormous energy savings. LED can produce cost-effective low-wattage irradiance at the specific wavelength. This study investigated the retinular responses of common squid T. pacificus to colored LED lights and light adaptation conditions based on the Perkinje effect, which is the tendency for the luminance sensitivity of the human eye to shift depending on the bright and dark adaptation states. The changes of the retinular response to blue, red and white LED were investigated in the bright and dark adaptation conditions in the water tank experiment. The degree of light adaptation was similar between the bright adaptation state and dark adaptation state to blue light, which suggests that squid retina is highly sensitive to blue light as it has been reported to date. On the other hand, the degree of light adaptation to red LED light showed a tendency to increase, albeit slightly, over time. However, the degree of light adaptation to white light with wide wavelength band showed similar tendencies as to the case of red light in the dark adaptation condition, and was actually superior to the case of blue light in the bright adaptation condition. Also, the degree of light adaptation of the retina cells collected from the sea experiment was found to be between the range of 20 and 40%. From these results, blue light may be regarded as an excellent luring source as the retina of squid is highly sensitive to it, but it cannot be determined as the most ideal LED color for the purpose of catching fish. [Copyright &y& Elsevier]

The interest in zero energy buildings is increasing in South Korea. Zero energy buildings need to save energy by using passive technology. The window performance is important to the thermal insulation of the building. Also, the government regulates the window performance through regulation and standards. However, it is difficult to predict window performance because the components of the window have become complicated due to the various materials used in the glass and frame. Based on window performance standards and regulations, the quality of window performance was managed. In this research, to consider thermal performance in proper window design in South Korea, we confirmed the impact on the thermal performance of the window through various kinds of materials and shapes. The authors also propose a window shape classification and frame calculation method based on actual test results. The authors analyzed the thermal performance data of the windows provided by the Korea Energy Agency and confirmed the change in the thermal performance of the windows by year and by frame material. The average U-value of the window decreased from 2012 to 2015 and maintained similar values until 2017. In 2018, this value was decreased to comply. Also, the authors confirmed the U-value of the windows through actual physical experiments and confirmed the change in thermal performance by the construction of the windows based on the results. The results show, in the case of aluminum windows, the U-value corresponding to Grade 3 (1.4–2.1 W/m2·K) was as high as about 60%. Regarding the analyzed results of the U-values of PVC windows, Grade 3 (U-value of 1.4–2.1 W/m2·K) accounted for about 35%, and Grade 2 (U-value of 1.0–1.4 W/m2·K) for about 29%. This paper also confirmed that the frame U-value of the PVC windows is lower than the frame U-value of the aluminum windows. Therefore, the authors proposed the performance index of the glazing part in PVC and aluminum window design. The results of this research can be used as basic data to identify problems in the method of determining the performance of windows in Korea. [ABSTRACT FROM AUTHOR]

Energy storage systems are an effective solution to manage the intermittency of renewable energies, balance supply, and demand. Numerous studies recommend adopting a shared energy storage system (ESS) as opposed to multiple single ESSs because of their high prices and inefficiency. Thus, this study examines a shared storage system in a grid-connected microgrid. By modifying the power outputs of the energy resources, this work intends to implement an economic dispatch of a shared ESS in order to satisfy the power balance and lower the overall cost of electricity. In this context, an optimization problem was formulated and developed using a mixed-integer linear programming (MILP) model. Furthermore, a pilot project (the Solar Decathlon Africa Village) in the Green & Smart Building Park (GSBP), Benguerir, Morocco, was employed to evaluate and verify the proposed approach. Some comparable scenarios were therefore run in a MATLAB environment. The collected findings demonstrate the efficacy of the developed algorithm in terms of optimizing energy cost reductions and enhancing the integration of renewable resources into the Moroccan energy mix. [ABSTRACT FROM AUTHOR]

One way to achieve carbon neutrality is by improving the energy performance of existing buildings, which requires accurate measurements. In particular, accurate measurement of heat loss coefficient (HLC) is critical because a building envelope is an important parameter of the energy performance analysis. The international standard for measuring HLC is heat flow meter (HFM) method in ISO 9869-1, which can be used to obtain the HLC at representative points on the building envelope. However, this approach does not account for the HLC of thermal bridges, which means that adding up the HLCs obtained for individual elements of the building envelope underestimates the total HLC of the building. In this study, the in situ thermal bridge measurement (TBM) method, which combines the HFM method and the coheating test, was proposed. In situ TBM can quantitatively measure the HLCs of multiple thermal bridges within an existing building envelope without requiring information on the internal structure or material properties. Measurement tests in an experimental chamber demonstrated that the in situ TBM method can be used to quantify the HLC of thermal bridges, which are missed when the HFM method is used alone. [ABSTRACT FROM AUTHOR]

The amount of heat lost through the envelope of a building is one of the most important variables that affects the energy performance evaluation of a house. In addition, it is especially important to estimate and accurately diagnose the amount of heat produced by windows. In Korea, windows' U-values reflect a building's initial design values and thermal characteristics that determine the thermal performance of an existing building, and is a factor that can overestimate the energy performance of a building. Therefore, there is a need for a field measurement method that can accurately measure the total U-value of windows in an existing house. This study provides a method of quantitatively measuring the total U-value of windows using the infrared (IR) method in ISO 9869-2. As a result of measuring the U-value using the infrared (IR) method, the Korean Standard (KS F 2278) for window performance test result values and the root mean square error (cvRMSE) for the U-value measurements using the IR method showed a high accuracy of about 3.29%. In addition, we confirmed that the IR method is an effective (cvRMSE about 7% improvement) method that can measure the comparison result faster than the heat flow meter (HFM) method, which is a conventional thermal performance measurement method. [ABSTRACT FROM AUTHOR]

In South Korea, about 40,000 buildings of low-income households have been diagnosed and remodeled annually by the Energy Welfare Program, using the normative method. The normative method is based on the heat gain elements of a building. In contrast, the performance-based method is based on the output derived from the thermal performance of each building part. In the normative method, there is no other building in which the input conditions of a building are perfectly matched. Further, cost-effective energy remodeling strategies vary according to the capacity of the diagnosis engineer. In this paper, we analyze the thermal performance of buildings by the performance-based method using indoor temperature, and examine the possibility of a database for the optimal remodeling method. For this, we analyzed more than 2500 simulation cases by combining thermal performance of each building part. The indoor temperature pattern can be similar even when the thermal performance of each building part is different. In buildings with similar indoor temperature patterns, the coefficient of variation of the root mean squared error of energy demand falls within the acceptable error range. Furthermore, changes in energy demand and predicted mean vote are similar when window thermal performance is changed. [ABSTRACT FROM AUTHOR]

Electricity demands are steadily increasing every year because of continued improvements to the quality of life and extreme hot and cold weather conditions. Therefore, the electric demand response management (DRM) system was introduced to prevent unstable electricity supply both domestically and globally. Unlike power generation in power plants, DRM regulates the demand and supply by reducing building energy consumption. Demand management is divided into energy efficiency and demand response. Energy efficiency reduces normal energy consumption by replacing older equipment and materials with high-efficiency models, remodeling the building envelope, and efficient system operation. Demand response reduces the electric consumption of pre-contracted electrical consumers at certain times, especially at peak load times. To determine the energy savings of buildings, the customer baseline load (CBL) is used. However, the CBL cannot evaluate the energy savings due to the energy efficiency improvements because it only assesses savings based on normal energy consumption. Therefore, DRM has a high incentive for buildings with high-energy consumption, while buildings with implemented energy efficiencies have low incentives, even though electricity demand is reduced. In this paper, we present the standard energy consumption to reflect both energy efficiency and demand response which can help stabilize power supply in the nation. [ABSTRACT FROM AUTHOR]

Simulations are widely used to calculate the thermal environment and energy consumption of buildings. The results of these simulations are affected by weather data, thus making the selection of appropriate weather data essential. Typical weather data are used to analyze a building’s thermal performance, but this is not appropriate for analyzing the performance of an actual building controlled by a building energy management system, which responds to real-time weather conditions. Such a building needs short-term weather forecast data to calculate the energy consumption. However, an evaluation of the validity of weather forecast data has not been performed. This study quantitatively analyzes the validation of real-time weather forecast data. A middleware platform was developed to combine weather forecast data and the EnergyPlus software using Grasshopper software. In addition, weather forecast data and actual weather data were compared to evaluate the forecast validation and a predictive control method using weather forecast data was devised. The application of real-time control was found to reduce the electricity costs incurred for cooling by 10% relative to there being no control, and by 2% relative to fixed temperature control. [ABSTRACT FROM AUTHOR]

The light-emitting diode (LED) market is expected to account for half of lamps worldwide in 2020. Despite the numerous benefits of LED lighting, the heat from LED lights affects indoor thermal conditions in buildings and increases the indoor cooling load in summer. A new method for integrating LED lighting with heating, ventilation, and air conditioning (HVAC) systems are proposed to prevent this heating effect in buildings by exchanging the lighting heat to outdoor and indoor spaces according to a seasonal operating strategy. Field measurements of a mock-up model were used to determine the lighting heat removal and reuse rates of the seasonal strategy. The ratio of lighting heat removal and reuse to LED input power was 70.3% in the summer test and 49.5% in the winter test. An indoor thermal effect analysis was performed using a simulation program with lighting heat input fractions obtained from the measured data. The sensible thermal loads in the mock-up chamber were reduced by 7.5% for cooling and 1.4% for heating using the proposed method, and the annual site energy reductions of reference office buildings were 8.5% for Houston, 8.1% for Atlanta, and 5.9% for Boulder, compared to the base case. [ABSTRACT FROM AUTHOR]

Highlights: [•] Application of heat control strategy reduces total energy consumption of LED lighting. [•] Convective heat from LED lighting should be emitted outdoors during cooling period. [•] Seasonal optimization of convective heat lowers total energy consumption. [ABSTRACT FROM AUTHOR]

Neural network models are data-driven and are effective for predicting and interpreting nonlinear or unexplainable physical phenomena. This study collected building information and heating energy consumption data from 16,158 old houses, selected key input variables that affect the heating energy consumption based on the collected datasets, and developed a deep neural network (DNN) model that showed the highest accuracy for the prediction of heating energy consumption in an old house. As a result, 11 key input variables were selected, and an optimal DNN model was developed. This optimal DNN model showed the highest prediction accuracy (R2 = 0.961) when the number of hidden layers was five and the number of neurons was 22. When the optimal DNN model was applied for the standard model of low-income detached houses, the prediction accuracy (Cv(RMSE)) of the optimal DNN model, compared to the EnergyPlus calculation result, was 8.74%, which satisfied the ASHRAE standard sufficiently. [ABSTRACT FROM AUTHOR]

The piezoelectric nanogenerator (PENG) has the potential to become a promising power supply for monitoring and sensors in Internet of Things (IoT) systems through wireless networks. In order to further increase the utilization of energy harvesters in an IoT system, we introduce a novel approach that greatly enhances the piezoelectric output performances by employing the layer-by-layer (LbL) method. Poly(vinylidenefluoride-co-trifluoroethylene) (PVDF-TrFE) polymer film, which has piezoelectric properties and mechanical flexibility, was used for the active layer in PENG. The maximum open-circuit voltage and closed-circuit current of the LbL multilayer PENG reached 34 V and 100 nA, respectively. In particular, the closed-circuit current of the LbL multilayer PENG was dramatically improved to be five times higher than that of the single-layer PENG. Furthermore, a supercapacitor was employed to investigate the energy storage capability of PENGs using different methods. The proposed LbL multilayer PENG is expected to be a candidate for a promising power supply for self-powered systems in the IoT system. [ABSTRACT FROM AUTHOR]