Passive Energy Research Articles

Evaluation of model predictive control (MPC) of solar thermal heating system with thermal energy storage for buildings with highly variable occupancy levels

The presence or absence of occupants in a building has a direct effect on its energy use, as it influences the operation of various building energy systems. Buildings with high occupancy variability, such as universities, where fluctuations occur throughout the day and across the year, can pose challenges in developing control strategies that aim to balance comfort and energy efficiency. This situation becomes even more complex when such buildings are integrated with renewable energy technologies, due to the inherently intermittent nature of these energy source. To promote widespread integration of renewable energy sources in such buildings, the adoption of advanced control strategies such as model predictive control (MPC) is imperative. However, the variable nature of occupancy patterns must be considered in its design. In response to this, the present study evaluates a price responsive MPC strategy for a solar thermal heating system integrated with thermal energy storage (TES) for buildings with high occupancy variability. The coupled system supplies the building heating through a low temperature underfloor heating system. A case study University building in Nottingham, UK was employed for evaluating the feasibility of the proposed heating system controlled by MPC strategy. The MPC controller aims to optimize the solar heating system’s operation by dynamically adjusting to forecasted weather, occupancy, and solar availability, balancing indoor comfort with energy efficiency. By effectively integrating with thermal energy storage, it maximizes solar energy utilization, reducing reliance on non-renewable sources and ultimately lowering energy costs. The developed model has undergone verification and validation process, utilizing both numerical simulations and experimental data. The result shows that the solar hot water system provided 63% heating energy in total for the case study classroom and saved more than half of the electricity cost compared with that of the original building heating system. The electricity cost saving has been confirmed resulting from the energy shifting from high price periods to medium to low price periods through both active and passive heating energy storages.

A Legal Framework for Energy-Conscious Urban Planning in Poland and Germany

This work seeks to answer the question as to whether the legal orders of Poland and Germany provide an effective framework for energy-efficient and climate-resilient urban space management. To this end, it verifies what similarities and differences exist between certain areas and whether they need reform. The starting point is the belief that legal instruments for environmentally friendly space management are a cross-border issue. Comparative studies are important because effective environmental protection knows no borders, and a lower level of protection in one country or geographic region can affect neighbouring countries and regions. The analysis of legal norms affecting such issues as passive energy construction; prevention of soil sealing and adequate ventilation; reduction of CO2 emissions; promotion of green areas; proper water management; reduction of so-called “grey energy” associated with new construction; the compact city; and a reduction of light pollution has enabled us to synthesise findings into specific conclusions and to propose postulates and directions for further research. However, this does not change the overall assessment that the legal systems of Poland and Germany enable environmentally friendly space management at a similar level, while at the same time, certain additions to the regulations and a further discussion of possible improvements are most welcome and needed.

Improving the Passive Building Energy Efficiency: A Case Study of a Moroccan Modern House

Improving the Passive Building Energy Efficiency: A Case Study of a Moroccan Modern House

An innovative I‐shaped low‐yield steel shear damper directly connected to the concentrically braced frame

AbstractShear dampers are known as famous seismic passive energy devices due to their suitable performance against seismic loading to improve the behavior of Concentrically Braced Frames (CBFs). The CBF system suffers from low ductility due to its compression member's susceptibility to buckling. By adding the shear dampers directly to the diagonal element members of the CBF, the dampers prevent the bucking of the CBF and improve the behavior of the system. Although the dampers pertain to high energy dissipation capacity, they reduce the ultimate strength and elastic stiffness of the system. To overcome the shortcoming, in this paper, utilizing low‐yield point steel to create an I‐shaped damper is proposed and investigated parametrically and numerically by the Finite Element Method (FEM). This damper is directly connected to the CBF's diagonal member. The results indicated that by using the proposed I‐shaped damper, the ultimate strength, elastic stiffness, and energy dissipation of the system are enhanced. Also, the damper prevents the bucking of the CBF, which causes the damages to be limited in the damper, and the CBF to remain in the elastic zone. Also, required equations were suggested to design the system.

Evaluation of the Seismic Performance of Single-Plate Metallic Slit Dampers Using Experimental and Numerical Data

Passive energy dissipation systems and devices are helpful in mitigating the danger of earthquake damage to structures. Metallic slit dampers (MSDs) are one of the most efficient and cost-effective solutions for decreasing seismic energy intake. The potential importance of MSDs in managing vibrations and limiting structural fatigue continues to grow as research advances and new materials and designs are introduced. This study evaluated the seismic performance of single-plate MSDs (SPMSDs) through a combination of numerical simulation and assessment of experimental results. ABAQUS software was used to create an assembly consisting of endplates, bolts, and SPMSDs. A real-world earthquake scenario was simulated using cyclic loads based on ASCE/SEI standards, and displacement-measuring devices such as strain gauges and LVDT were employed to record the behavior of the SPMSDs. The results of the experiment are used to assess the compliance of the SPMSDs and discuss their behavior as they undergo minimum and maximum displacements due to minimum and maximum applied forces. The energy dissipation capabilities of the dampers are presented by analyzing and comparing the area of their hysteresis loops, equivalent viscous damping, and their damping ratios. Actual failure modes are identified and shown to describe the limitations and potential vulnerability of the dampers. The relative error between the lowest and greatest recorded forces from experimental data and numerical simulation ranges from 4.4% to 5.7% for SPMSD 1 and from 1.6% to 2.1% for SPMSD 2, respectively. These deviation values represent a satisfactory level of precision, demonstrating that the numerical simulation accurately predicts the actual performance and behavior of the dampers when subjected to cyclic stress. The topology optimization performed in this study yielded an improved geometry of the SPMSD suited for a corresponding maximum considered earthquake (MCER) displacement of ±33 mm. This research also suggests practical implementations of the investigated and improved SPMSDs.

Design optimization of a single-mass impact damper

This research article presents a numerical approach to establish an optimal design methodology for a single-mass impact damper (SMID), which is a passive energy dissipation device with robust performance. Due to the nonlinear characteristics of SMID and a lack of analytical models, designing a single-mass impact damper with optimal combination of the parameters has been challenging. Furthermore, an uncontrolled mass of the SMID on a vibrating structure may lead to chaotic vibration responses. This study identifies a range of design parameters of the SMID to ensure non-chaotic responses and validates the optimal design combinations using an experimental prototype. The results show that a single-mass impact damper designed with the optimal combination of design parameters can provide better vibration damping and relatively steady response. This study also compares the performance of an optimized single-mass impact damper with an optimized tuned mass damper and finds that the single-mass impact damper can work more effectively than the tuned mass damper in damping free vibrations of a single-degree-of-freedom primary structure. Although the SMID cannot suppress forced vibration amplitude as effectively as a tuned mass damper (TMD) at resonance, it has the advantages of lower cost and easier installation than the TMD. Overall, this study provides a basis for the optimal design of a single-mass impact damper and resolves the issues related to design methodology and chaotic vibration response with a single-mass impact damper.

Passive Window Energy Performance in Buildings: Modeling of Apartment Buildings in Indonesia

Along with urban growth in urban areas and energy consumption, which continues to increase every year, the selection of windows in the initial design is essential to obtain buildings that are not energy intensive. Selecting the correct window in the blueprint design reduces building energy consumption. Smart windows, especially thermochromic windows, are one of the most promising window technologies because they are the most economical and have passive control with zero energy input, which holds good promise for energy-saving applications. Apart from that, double-glazing windows are also frequently used in energy-saving applications. Therefore, a study compared the energy-saving potential of thermochromic and double-glazing windows to clear glass windows, using computer modeling through EnergyPlus, in high-rise apartment buildings in cities throughout Indonesia's diverse climates. From the modeling results, total energy consumption can be reduced by around 8.91% to 10.96% of total building energy consumption by replacing the conventional clear glass with double-glazing windows or more able to reduce about 20.22% to 24.19% by replacing the conventional clear glass with thermochromic windows. Furthermore, this potential varies depending on geometric shapes, materials, building facades, local climate, and building orientation. Nevertheless, considering the potential benefits, these windows are highly suitable for application in buildings seeking to reduce their energy consumption and improve energy efficiency.

Cyclic behavior of a slit damper proposed for precast concrete beam-column connections

Since the 2017 Puebla-Morelos Earthquake, interest in limiting damage to structural components has exponentially increased in Mexico. Consequently, the use of energy dissipation devices has received renewed attention. Following that line, this paper studies an attractive solution, which is a slit damper proposed as a passive energy dissipation device for, but not limited to, precast beam-column connections. Slit dampers have been studied for their cost-effectiveness and ease of application. They present stable hysteretic behavior and dissipate substantial amounts of energy under cyclic loading while maintaining less ductile elements essentially elastic. The structural behavior of the proposed device was evaluated theoretically, followed by experimental verification. Quasi-static incremental and constant-amplitude cyclic tests were conducted on eight specimens, with two of them having non-uniform struts. Test results are presented and discussed, emphasizing ductility and energy dissipation capacity. The proposed damper showed stable hysteretic behavior and adequate seismic performance. Using non-uniform struts significantly increased the damper's deformation capacity and fatigue performance, which is desirable for seismic zones where long-duration earthquakes are expected, such as in Mexico City. Numerical modeling techniques were also validated with finite element analyses. It was shown that the proposed damper's hysteretic response could be accurately predicted using the combined non-linear isotropic and kinematic hardening model.

Investigation of Submergence Depth and Wave-Induced Effects on the Performance of a Fully Passive Energy Harvesting Flapping Foil Operating Beneath the Free Surface

This paper investigates the performance of a fully passive flapping foil device for energy harvesting in a free surface flow. The study uses numerical simulations to examine the effects of varying submergence depths and the impact of monochromatic waves on the foil’s performance. For the numerical simulations, a in-house artificial compressibility two-phase solver is employed and coupled with a rigid body dynamic solver. The results show that the fully passive flapping foil device can achieve high efficiency for submergence depths between 4 and 9 chords, with an “optimum” submergence depth where the flapping foil performance is maximised. The effects of regular waves on the foil’s performance were also investigated, showing that waves with a frequency close to that of the natural frequency of the flapping foil-aided energy harvesting. Overall, this study provides insights that could be useful for future design improvements for fully passive flapping foil devices for energy harvesting operating near the free surface.

Comprehensive renovation of a multi-apartment building in Sweden: techno-economic analysis with respect to different economic scenarios

ABSTRACT A wider deployment of nearly zero energy buildings (NZEBs) is expected to contribute to the transition to a decarbonized and energy-efficient building sector in Europe. This study proposed an integrated energy-economic analysis to exemplify the feasibility of NZEB renovation in temperate climate. A parametric analysis was performed to identify technical building system configurations that give minimum share of renewable energy systems contributing to NZEB level. Final energy savings, global costs and cost-effectiveness of renovating a building to NZEB level are analysed, considering active and passive energy efficiency measures (EEMs). The active EEMs included efficient water taps and heat recovery ventilation, and the passive EEMs encompassed insulations to roof, exterior walls and ground floor, and improvements of windows and doors. The building had initial final energy use of 133 kWh/m2 year for space heating, domestic hot water production (DHW) and facility electricity. The results show that NZEB level is achieved with active and passive EEMs, without renewable energy systems for scenarios with low discount rates and high future energy price escalations. The annual final energy use for space heating, DHW and facility electricity is reduced cost-effectively by 37-54%. Furthermore, increasing size of PV-system enhanced cost-effectiveness by lowering total global costs.

Determining the optimum span of a solar greenhouse

The span of a solar greenhouse is a crucial parameter determining its architectural space form characteristics, which in turn directly influences the passive solar energy utilization and light-heat environment within the greenhouse. As a result, building on prior research concerning the optimal orientation and height-span ratio of solar greenhouses, this study delves into the key factors affecting the optimal span and its evaluation indices. Global solar radiation is broken down into direct radiation and diffuse radiation, both of which serve as input parameters for Energy Plus weather files. Additionally, the soil temperature calculation model within a solar greenhouse is employed as the input condition for “Ground temperature” boundary conditions in Energy Plus. The field test demonstrates the efficacy of the Energy Plus model. Taking the calculation results into account, this research provides a comprehensive analysis of the impact of outdoor air temperature, solar radiation, north wall height, heat storage capacity, and soil temperature inside the greenhouse on the thermal environment when the span is altered. A simplified calculation model for determining the optimal span of solar greenhouses across various latitudes in China is proposed based on the optimal span evaluation index. Field tests confirm the effectiveness of this calculation model. This study enhances the design and calculation methods for optimal space form characteristic parameters of solar greenhouses. Furthermore, it offers an analytical method reference for the optimal design of solar greenhouses, efficient construction of thermal environments, and intelligent management and control.

Effect of training on the cyclic behaviour of SMA wire

Shape memory alloys (SMAs) are a new generation of smart metallic materials with numerous unique and widely applicable characteristics. With their superelasticity and ability to dissipate energy under cyclic loading, SMAs are an excellent choice for passive vibration energy dissipation systems. However, due to functional fatigue, the energy dissipation and re-centring capacity of virgin SMA dwindles at a decreasing rate during cyclic loading and eventually reaches a stable level. Since for vibration control applications stable mechanical properties with predictable responses to vibrational forces are preferred, preloading SMA wires for mechanical training is proposed to overcome this drawback. Nevertheless, the effect of training conditions on the mechanical behaviour of SMA wires has only been investigated in a few studies. To fill this research gap, the influence of different training parameters, such as strain amplitude, frequency, number of cycles and prestrain, on the mechanical behaviour of SMA wires is examined. The results show that while a sufficient number of cycles and certain level of strain amplitude are required to reach a stable stress–strain relation, training frequency is the most important parameter for eliminating residual strain.

An innovative shear links as dampers compound of shear plates and round HSS sections

Though concentrically braced frames pertain to high elastic stiffness and strength, their low ductility has been introduced as a no-desirable system in the high seismic risk zone. Utilizing passive energy dampers as a capable and economical idea, the shortcoming can be solved. Experimental and numerical studies on the pipe dampers confirmed their satiable performance in the case of ductility and dissipating energy capacity. But, it is suffered from low strength and stiffness. To overcome the shortcoming of these types of metallic dampers, in this paper, the strengthening of pipe damper with shear plates is proposed and investigated numerically and parametrically. Subsequently, the required equations (in good agreement with finite element results) were presented to design and predict the behavior o the damper. Results indicated that by reduction of the length to the height of the damper, the strength and stiffness are improved. Also, the ratio of the strength of the flanges to the strength of the web affects the behavior of the damper, and increasing this ratio reduces the stiffness and ultimate strength. Therefore, it is suggested that this ratio should be greater than 1.5.

A novel high-performance three-phase magnetic field energy harvester for powering up vehicle onboard electronics

The boosting development of vehicle electrification and onboard sensing networks in the intelligent vehicle era poses a significant challenge to conventional electrical power supply systems. This study developed a novel passive three-phase magnetic field energy harvester (TMEH) for reliable and sustaining power to drive vehicle onboard electronics, which recycles the induced magnetic field energy around the power lines of a permanent magnet synchronous motor (PMSM) on an electric vehicle (EV). A Y-Y topological connection pattern for three-phase coils was designed to enhance and stabilize the TMEH output performance. Furthermore, three auto-shift operating modes were assigned to the TMEH to tackle the dynamic changes of the captured power caused by unpredictable vehicle manoeuvres and road conditions. The theoretical model and numerical method were also established for structural optimization of the TMEH, followed by a series of experimental tests for highlighting the impacts of the power lines carrying alternating current on TMEH. The results have indicated that the proposed TMEH showed impressive energy conversion efficiency, providing an independent power supply for sensors and other electronics applications on a 4 kW-PMSM driven EV. Bench testing results and practical EV driving trials demonstrated the capability of the TMEH prototype to power up multiple types of sensors and electronic devices under most EV driving conditions. Specifically, an average power of 5.69 W and power density of 123.85 mW/cm3 were generated by the harvesting coils when excited by a 50 A current at 50 Hz. Furthermore, the maximum TMEH energy conversion efficiency of 41.9% at the excitation current frequency of 50 Hz is obtained in laboratory conditions. In EV driving tests at speeds of 20–30 km/h, the TMEH presented steady output power up to 5.98 W, capable of driving various loads such as an electronic resistor, Li-ion battery, GNSS/INS device, driving recorder, and cellphone, either with the employment of one or two sets of harvesting coils. The approach of this study offers a promising application scenario to power up numerous electronics on a commercial transport EV platform driven by a more powerful PMSM.

Ultra-sensitive voltage-controlled skyrmion-based spintronic diode

We have designed a passive spintronic diode based on a single skyrmion stabilized in a magnetic tunnel junction and studied its dynamics induced by voltage-controlled magnetic anisotropy (VCMA) and Dzyaloshinskii–Moriya interaction (VDMI). We have demonstrated that the sensitivity (rectified output voltage over input microwave power) with realistic physical parameters and geometry can be larger than 10 kV W−1 which is one order of magnitude larger than diodes employing a uniform ferromagnetic state. Our numerical and analytical results on the VCMA and VDMI-driven resonant excitation of skyrmions beyond the linear regime reveal a frequency dependence on the amplitude and no efficient parametric resonance. Skyrmions with a smaller radius produced higher sensitivities, demonstrating the efficient scalability of skyrmion-based spintronic diodes. These results pave the way for designing passive ultra-sensitive and energy efficient skyrmion-based microwave detectors.

Experimental Study of the Heat Flow and Energy Consumption during Liquid Cooling Due to Radiative Heat Transfer in Winter

Radiation cooling is a passive energy saving cooling technology. The process of cooling heat transfer liquid due to the combined effect of night radiative cooling and convection of air at negative temperatures (in winter) is studied. The radiator used for cooling was built into the roof of the building. Its radiating plate was made of a steel sheet coated with zinc oxide. In it, heat dissipation was carried out both from the upper and lower sides of the radiating plate. The experimental values of the heat flux ranged from 20 to 80 W·m−2 at a temperature difference between heat transfer liquid and air from 5 to 15 °C and ambient air temperature from −17 to +5 °C. The correctness of the model for calculating the heat flux in winter conditions was confirmed. A theoretical calculation showed that, in winter, the heat flux removed by the radiator will be 15% less than the heat flux in summer. The amount of heat transferred per watt of electrical power of the refrigeration unit reached 8 W·W−1. To keep the refrigeration unit with radiative heat transfer more efficient than in a conventional vapor compression chiller, the heat transfer liquid temperature should be 6 °C above the atmospheric temperature air. The results of the study show that radiative cooling can be used in winter and may be useful for the development of energy-efficient cooling systems for various purposes (air conditioning, industrial cooling systems and fruit storage chambers).

Ontogenetic transitions, biomechanical trade-offs and macroevolution of scyphozoan medusae swimming patterns

Ephyrae, the early stages of scyphozoan jellyfish, possess a conserved morphology among species. However, ontogenetic transitions lead to morphologically different shapes among scyphozoan lineages, with important consequences for swimming biomechanics, bioenergetics and ecology. We used high-speed imaging to analyse biomechanical and kinematic variables of swimming in 17 species of Scyphozoa (1 Coronatae, 8 “Semaeostomeae” and 8 Rhizostomeae) at different developmental stages. Swimming kinematics of early ephyrae were similar, in general, but differences related to major lineages emerged through development. Rhizostomeae medusae have more prolate bells, shorter pulse cycles and higher swimming performances. Medusae of “Semaeostomeae”, in turn, have more variable bell shapes and most species had lower swimming performances. Despite these differences, both groups travelled the same distance per pulse suggesting that each pulse is hydrodynamically similar. Therefore, higher swimming velocities are achieved in species with higher pulsation frequencies. Our results suggest that medusae of Rhizostomeae and “Semaeostomeae” have evolved bell kinematics with different optimized traits, rhizostomes optimize rapid fluid processing, through faster pulsations, while “semaeostomes” optimize swimming efficiency, through longer interpulse intervals that enhance mechanisms of passive energy recapture.

Review of Active Circuit and Passive Circuit Techniques to Improve the Performance of Highly Efficient Energy Harvesting Systems

In piezoelectric energy harvesting systems, energy harvesting circuits are the interface between piezoelectric devices and electrical loads. The conventional view of this interface is based on the concept of impedance matching. In fact, in the power supply circuit can also apply as an electrical boundary conditions, such as voltage and charge, to piezoelectric devices for each energy conversion cycle. The major drawback of piezoelectric power harvesting have low-power relationships in systems within (in the range of μW to mW), then system also have significantly reduced any potential losses in circuits that make up the EH system, whereas other condition into careful selection of circuits and components can enhanced the energy harvesting performance and electricity consumption. In the study of energy harvesting systems, it is an energy harvesting system approach that using active and passive electronic circuit to control voltage and or charge on piezoelectric devices as proposed and review to mechanical inputs for optimized energy conversion. Several factors in the practical limitation of active and passive energy consumption, due to device limitations and the power efficiency of electronic circuits, will be introduced and have played an important role into to enhance optimum and increase efficiency of energy harvesting system.

Crashworthiness Analysis of Thin-Walled Square Columns with a Hole Trigger.

Thin-walled structures dynamically loaded with an axial force are the subject of this study. The structures work as passive energy absorbers by progressive harmonic crushing. The absorbers were made of AA-6063-T6 aluminum alloy and subjected to both numerical and experimental tests. Experimental tests were performed on an INSTRON 9350 HES bench, while numerical analyses were performed using Abaqus software. The energy absorbers tested had crush initiators in the form of drilled holes. The variable parameters were the number of holes and their diameter. The holes were located in a line 30 mm away from the base. This study shows a significant effect of the hole diameter on the values of the stroke efficiency indicator and mean crushing force.

Investigation of the impact of phase change materials at different building envelope placements in a semi-arid climate

Researchers in the building industry are becoming increasingly interested in phase change materials (PCM). Due to the potential for passive temperature management offered by these PCMs, HVAC (Heating, Ventilation, and Air-Conditioning) equipment will use less energy. Still, to prevent leakage during phase change, an enclosure is needed when installing PCMs in buildings. So, to determine this passive indoor temperature regulation cost, payback period, and energy savings, it is crucial to assess the PCM energy savings in various building envelope placements. So, this is done by using the EnergyPlus simulation engine for the case of the commercial PCM RT 28HC, this article will assess and compare 8 potential building envelope positions in a semi-arid region. These eight different building configurations have one case without PCM and the other cases have PCM placed in the interior surface of the following specific placements, a PCM placed in walls envelope only, in floors envelope, in ceilings and roofs envelope only, in walls, ceilings, and roofs envelope, in walls and floors envelope only, in floors, ceilings and roofs envelope and all envelopes for a 10 m square-shaped building. This study's primary goal is to evaluate the reduction of indoor air temperature fluctuations, PCM energy savings, PCM activation, and payback period for these various building layouts. The findings show excellent temperature indoor stabilization in summer, for the case with PCM installed on all interior envelope surfaces showing a maximum indoor temperature fluctuation decrease of 110.2 °C for August. In addition, the case with the PCM placed only in the walls, roof, and ceilings has shown the highest yearly energy savings, nevertheless, the case with PCM placed only in the walls has the lowest payback period of nearly 22 years and a half.