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In relation to recent attention focused on the use of energy by lighting, there is a large potential for commercial buildings to save energy in this respect. The use of energy-saving bulbs or dimming controls triggered by daylight, not only enables lighting energy saving, but delivers cooling energy through a reduction in indoor heat production. In this study, we examine the energy use in commercial buildings by evaluating lighting energy saving methods and the effect of using dimmer controls with a heat control method, which can both maximize the cooling load reduction during summer and save energy. Results show that the total energy from the reference commercial building was reduced by 20.9% by replacing LFL T12 bulbs with LEDs, together with an additional saving of 19.9% in cooling energy by using the lighting heat & dimming control method. [ABSTRACT FROM AUTHOR]

Temperature restriction in indoor environment is a simple way of saving energy; however, it may cause discomforts to the people in such an indoor environment. The discomfort is aggravated when the environments of different rooms cannot be controlled individually. Furthermore, the discomfort is intensified during the intermittent seasons. Thermal comfort is estimated by the Predicted Mean Vote (PMV) model based on six parameters. This is a complex procedure and has limitations because a number of measurement indices have to be known. Hence, we analyzed the major variables of PMV and simplified the parameters in order to implement the model without incurring additional cost or installing equipment such as sensors. In addition, we compared the simplified PMV control with a control based on room temperature. The simplified PMV control realizes 7.0% more thermal comfort and 5.6% more energy reduction than those achieved by room temperature control, especially in the intermittent operation period. [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]

To achieve carbon neutrality, the South Korean government has been retrofitting existing buildings to reduce their energy consumption. However, existing buildings often lack sufficient information for building energy modeling. In this study, a model was developed for predicting heating energy demand using only information obtained from a preliminary survey. Three different models were considered: multiple linear regression (MLR), artificial neural network (ANN), and support vector regression (SVR). They were then trained with data on old houses of low-income households in South Korea and were used to predict the heating energy demand of individual household units. Different input variables were applied to the initial models to identify target variables and tune the hyperparameters. In tests, ANN was slightly more accurate than SVR. SVR required a shorter total running time (training and prediction), but ANN was 10 times faster than SVR when only prediction was considered. Therefore, ANN was selected. The selected model method takes 0.215 s for 10,000 cases. On the other hand, the previous method takes approximately an hour for one case except time for moving to a field. This shows the suggested method is much faster than the previous one. The proposed model was applied to a case study, and the predicted and true values had a relative error of only 1.40%. The proposed model can be used to predict the heating energy demand of old houses while requiring only the heating area and construction year as inputs. • The purpose is to predict the energy demand of old houses with limited information. • Input variables were selected to reduce work steps using data-driven approaches. • This study considered MLR, ANN, and SVR, and ANN was the optimal model. • Using the developed ANN model can save time and labor. • The suggested model can be applied to an un-tact method. [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]

As a result of industrialization and urbanization, several harmful factors such as the presence of particulate matter (PM) and yellow sand in the atmosphere, have become an issue. As the interest in improving the air quality has increased, the market for high performance air cleaning products able to filter even exceedingly small dust particles is rapidly expanding. In this study, we present a flexible dielectric film that can adsorb PM using triboelectricity. Without the problem of pressure loss or generation of hazardous substances that occurred in previous filters, this polydimethylsiloxane (PDMS)-based flexible dielectric film could be attached to an electric fan and PM can be removed. Triboelectricity is induced by the friction between PDMS and metal nanoparticles when vibration resulting from an external energy source occurs. It was experimentally confirmed that the PM removal efficiency of the PDMS-based flexible dielectric film was 20% higher than that of the control group, based on the standard 95% removal of PM. We expect that the proposed electrostatic film could be used as a highly efficient, flexible, and washable filter in PM removal systems. Image 1 • Flexible dielectric film can adsorb particulate matter (PM) using triboelectricity. • Triboelectric nanogenerator (TENG) was employed to compare the charging effects of dielectric film. • We have clearly demonstrated a PM adhesion film and experimentally analyzed its collection effect of PM 10 and PM 2.5. • This study can provide new insight into PM adhesion systems considering application, air speed, and reuse after washing. [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]

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]