Increasing Energy Costs Research Articles

Proactive preventive maintenance policy for buffered serial production systems based on energy saving opportunistic windows

Abstract Nowadays the manufacturing enterprises are driven towards significant energy improvements by increasing energy costs and sustainability awareness, and energy consumption and energy efficiency are taking a more and more dominating position in the decision-making process of manufacturing enterprises. However, in the process of production, existing researches rarely integrate energy management with conducting preventive maintenance at the strategic level, ignoring energy-saving opportunities that may arise during machines’ downtime. This paper considers a serial production system with intermediate finite buffers. Based on the concept of “energy-saving opportunity window” and the modelling of the continuous deterioration process of each machine, the window of energy-saving opportunity of the production system is regarded as a window of opportunity for the preventive maintenance, thus a proactive preventive maintenance strategy is proposed. The serial production system is modeled and the impact of different maintenance thresholds on the energy efficiency is explored by means of Monte Carlo simulation. For purpose of maximizing the energy efficiency of the entire production system, an iterative algorithm for solving the optimal preventive maintenance thresholds is presented as well. The numerical analysis with other maintenance strategies shows that the proposed strategy is more competitive in improving the effective throughput while reducing the overall energy consumption.

Dynamics and energy provision of cargo transportation systems in food packing lines

The work is related to the search for the possibilities of using internal energy resources in transport and technological systems by the example of food packaging lines packed in glass containers. Trends in switching to high-performance lines have led to the need for their equipment with dual-purpose transport systems. Obviously, the first task is to ensure the movement of artificial products in the respective sections between units of technological machines, and the second component of their task - to fulfill the role of storage devices in combination with the need for restructuring mass flows. This combination of tasks has led to the exclusive use of closed circuit circuits with two friction planes in transport systems. Meanwhile, it is known that energy costs in mechanical systems are associated with the need to achieve the specified levels of kinetic energy of the moving masses in order to overcome the forces of harmful and useful resistance. The peculiarity of such transport systems is the constant presence of transients and dynamic components of loads. The study complements the known dynamic manifestations with new ratios of indicators for the possibility of energy recovery. In the transportation systems for glass production of foodstuffs, the driving factors in most cases are represented by friction forces. Simultaneously, the closure of kinematic pairs between the products and the supporting moving planes is due to gravity forces, which, in cases where their velocities do not coincide, leads to the formation of an additional friction plane with a corresponding increase in energy costs and dynamic components of the loads. The uneven velocity of the closed circuit circuits is accompanied by additional relative displacements at certain ratios of kinematic and geometric parameters. An appropriate set of parameters is achievable by eliminating these additional displacements of the product arrays relative to the reference planes and limiting energy costs. The use of rigid kinematic bonds in parallel systems allows for changes in velocities in counter-phases and provides energy recovery. With stabilized kinematic parameters, compared to single-stream systems, higher loads of drive motors with improved performance are achieved.

Parameters that Affect Electricity Consumption in Fish Freezing. Case Study

Abstract Reducing energy consumption in industry has become an important aspect on a global scale. Energy efficiency is one way of reducing energy consumption and promoting competitiveness. Increasing energy costs, security of energy supply, emissions from energy production have shown that current freezer design solutions are not sustainable. The food industry has a common tendency, whereby energy costs are only of secondary importance, unlike other production costs, resulting in minimal monitoring of energy consumption. Electricity consumption for freezer operation amounts to 20 % of total electricity consumption. Within the framework of this study, electricity consumption for fish freezing and storing frozen fish and finished products, as well as the coefficient of performance (COP) for compressors and parameters affecting COP were analyzed. From the results it can be concluded that the specific consumption of electricity in freezing of fish is lower than that of frozen fish storage. The two-stage compressor COP ranges from 2.4 to 3.7, but the single-stage compressor COP ranges from 3.7 to 5.5. The pressure in the condenser and ammonia vapor temperature after the compressor is affected by the temperature of the water used to cool the condenser and compressors. As the temperature of the water used for cooling increases, the condenser and ammonia vapor temperature after the compressor increase, which in turn reduces the compressor COP.

Quality-Based and Energy-Efficient Data Communication for the Internet of Things Networks

Large volumes of real-world observation and measurement data are collected from sensory devices in the Internet of Things (IoT) networks. IoT data is often generated in highly distributed and dynamic environments. Continuous transmission of large volumes of data collected between sensor and head/sink nodes induces a high communication cost for individual nodes. This results in a significant increase in the overall energy cost for IoT applications such as environmental monitoring. Decreasing data transmission between nodes can effectively reduce energy consumption and prolong the network lifetime, especially in battery-powered nodes/networks. In this article, we describe an adaptive method for data reduction (AM-DR), a data reduction approach for reducing the overall data transmission and communication between sensor nodes in IoT networks such that fine-grained sensor readings can be used to reconstruct the original data within a user-defined accuracy boundary. Evaluation with real-world data shows that AM-DR achieves a communication reduction in some scenarios up to 95% while retaining a high prediction accuracy. To fully achieve the energy savings enabled by AM-DR, we provide a communication cost model. The proposed model is also integrated into the LEACH protocol to demonstrate how our proposed approach reduces energy consumption and effectively prolongs the network lifetime.

Effects of phosphate and hydrogen peroxide on the performance of a biological activated carbon filter for enhanced biofiltration

Biofilm formation on biofilters can influence their hydraulic performance, thereby leading to head loss and an increase in energy use and costs for water utilities. The effects of a range of factors, including hydrogen peroxide and phosphate, on the performance of biological activated carbon (BAC) and biofilm formation were investigated using laboratory-scale columns. Head loss, total carbohydrates, and proteins were reduced in the nutrient-enhanced, oxidant-enhanced, and nutrient + oxidant-enhanced BAC filters. However, there were no changes in the removal of dissolved organic matter, trihalomethane formation potential, or selected trace organic contaminants. The biofilm formation on polyvinyl chloride and stainless steel coupons using the laboratory biofilm reactor system was lower when the effluent from a nutrient-enhanced column was used, which indicated that there was less biofilm formation in the distribution systems. This may have been because the effluent from the nutrient-enhanced column was more biologically stable. Therefore, enhanced biofiltration could be used not only to reduce head loss in biofilters, but also to delay biofilm formation in distribution systems.

The Impact of Prediction Errors in the Domestic Peak Power Demand Management

In this article, the impact of prediction errors on the performance of a domestic power demand management is thoroughly investigated. Initially, real-time peak power demand management system using battery energy storage systems (BESSs), electric vehicles (EVs), and photovoltaics (PV) systems is designed and modeled. The model uses real-time load demand of consumers and their roof-top PV power generation capability, and the charging-discharging constraints of BESSs and EVs to provide a coordinated response for peak power demand management. Afterward, this real-time power demand management system is modeled using autoregressive moving average and artificial neural networks-based prediction techniques. The predicted values are used to provide a day-ahead peak power demand management decision. However, any significant error in the prediction process results in an incorrect energy sharing by the energy management system. In this research, two different customers connected to a real-power distribution network with realistic load pattern and uncertainty are used to investigate the impact of this prediction error on the efficacy of an energy management system. The study shows that in some cases the prediction error can be more than 300%. The average capacity of energy support due to this prediction error can go up to 0.9 kWh, which increases battery charging-discharging cycles, hence reducing battery life and increasing energy cost. It also investigates a possible relationship between environmental conditions (solar insolation, temperature, and humidity) and consumers' power demand. Considering the weather conditions, a day-ahead uncertainty detection technique is proposed for providing an improved power demand management.

Küçük Hidrolik Santrallerde Kapasite Faktör Analizi Ve Giresun Özelinde Bir Uygulama

Energy is the fundamental element of social and economic sustainability in every aspect of life, from the smallest living body to large scale industrial facilities. In Turkey rapidly increasing industrial development process lead to extensive energy demand, which is met largely from imported fossil sources. Especially in recent years, as a result of increasing environmental awareness and economic and strategic reasons, a portion of the energy deficit is fed from, clean and reliable hydroelectric power plants with great importance. In our country, a total of 295511 GWh electricity was produced in 2017. About 41368 GWh (14%) of the total amount was generated by large hydraulic plants and 17082 GWh (5.78%) by small hydraulic plants. In this study, small hydroelectric power (SHP) stations are considered to reduce the increasing energy cost and for this purpose SHP in Giresun are analyzed leading to private additives in the capacity factor analysis. According to the results it is possible to conclude that thetime of power plant investment is shortened as the capacity factor increases in hydroelectric power plants.

Biomechanical factors affecting energy cost during running utilising different slopes

ABSTRACTThis study aimed to examine the characteristics of electromyography (EMG) and kinematics of the supporting leg affecting energy cost while running at incline, level, and decline slopes. Twelve male Japanese middle- and long-distance runners volunteered for this study. The subjects were asked to run at 13.5 km·h−1 on a treadmill under three slope conditions. Sagittal plane kinematics and the EMG of the lower limb muscles, respiratory gases were recorded. Energy cost differed significantly between slopes, being the lowest in decline slope and the greatest in incline slope. Integrated EMG (iEMG) of leg extensor muscles was greater in the incline slope than in the decline slope, and iEMG of the gastrocnemius and soleus muscles correlated positively with energy cost. The knee and ankle joint kinematics were associated with energy cost during running. In incline slope, the knee and ankle joints were more extended (plantarflexed) to lift the body. These movements may disturb the coordination between the ankle and knee joints. The gastrocnemius muscle would do greater mechanical work to plantarflex the ankle joint rather than transfer mechanical energy as well as greater mechanical work of mono-articular muscles. These muscular activities would increase energy cost.

1177Insights on mitochondrial energetics in obstructive hypertrophic cardiomyopathy

Abstract Background Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiomyopathy, heterogeneous in phenotype and clinical course. The genotype-phenotype relationship and associated molecular mechanisms are still incompletely understood. In the HCM milieu, increased energy cost of force production, impairing performance and mitochondrial function, may be associated to patients' genotype and/or phenotype. Purpose To determine abnormalities in mitochondrial energetics in HCM and their possible relationship with genotype and clinical phenotype of patients. Methods Septal myectomies from characterized patients with obstructive HCM (HOCM, n=18) and donor hearts discarded from transplantation (CTRL, n=8) have been compared. HOCM patients were screened and demographic, clinical and instrumental data (routine ECG, echocardiography and cardiac magnetic resonance-CMR) were collected. Genetic analysis was performed on total DNA extracted from myectomies by NGS on MiSeq platform using the TruSight Cardio Sequencing kit and testing a panel of 26 genes. Activity and amount of mitochondrial enzymes generating/scavenging reactive oxygen species were investigated. Results Within the HOCM cohort 30% of patients was bearing mutations in sarcomeric genes associated with HCM. The amount and/or activity of mitochondrial Complex I NADH dehydrogenase, of SOD2 and (m)-aconitase were upregulated in HOCM vs. CTRL. NADH dehydrogenase level was inversely correlated with the degree of mitral valve regurgitation and mitral valve backward volume by CMR (Spearman R=−0.5 and −0.8, respectively). The Complex V enzyme ATP synthase activity decreased, whilst its amount was comparable in HOCM vs. CTRL. Analogously the SOD1 activity was similar in HOCM and CTRL. No difference in mitochondrial DNA (mtDNA) copy number was found. Results were unrelated to HCM-associated mutations. Conclusions HOCM hearts are characterized by mitochondrial hyperactivity aimed at quenching reactive oxygen species, but decreased ATP synthase activity. Overall, these data suggest an abnormal mitochondrial activity in the myocardium of HOCM patients independent of the presence of HCM-associated mutations. Moreover, our results underpin the markedly abnormal cellular energetics of HOCM, identifying potential therapeutic targets. Acknowledgement/Funding NET-2011-02347173, Italian Minister of Health

Simulation of a controlled water heating system with demand response remunerated on imbalance market pricing

Buildings are responsible for 40% of our worldwide energy consumption and 50% of this energy is converted for Heating Ventilation Air Conditioning (HVAC) systems in buildings. The increasing share of renewable energy production required to make the transition towards a carbon neutral energy system challenges the stability of the grid. Through demand response it becomes possible to activate these systems in support of grid balancing. However, this flexibility is currently not rewarded in the market. We simulate a domestic water heater participating in the balancing of the electricity net and calculated the revenue from this action. We simulate a water heater in connection with an Economic Model Predictive Controller (EMPC) which takes future usage, energy cost, and reward for delivering balanced power into account. We show that the choice of an EMPC controller is valid as it allows the setpoint to change if certain conditions are met, leading to a more optimal revenue stream from selling flexibility. We find that the economic benefits of participating in delivering balancing power is considerable and offset an increase in energy costs. The increase in energy consumption could be justified as the participation in net stabilisation allows the macro-system to integrate more renewable energy sources. More importantly, the simulations also show that the poorer the energy performance of the water heater, the more flexibility can be sold. From a policy point of view, a minimal energy performance should be determined before allowing participation in net stabilisation.

The association between gait variability with the energy cost of walking depends on the fall status in people with multiple sclerosis without mobility aids

BackgroundFalls, gait variability and increased energy cost of walking are common in people with multiple sclerosis (PwMS). However, no studies have as yet examined this triple association in PwMS or in other neurological populations. Research questionDoes a relationship exist between gait variability, falls and the energy cost of gait in PwMS? MethodsThis cross sectional study included 88 PwMS (50 women), mean age 39.8 (S.D = 13.0) and mean disease duration of 6.2 (SD = 8.2) years since diagnosis. Energy expenditure during walking was collected via a portable metabolic device (COSMED K5, COSMED Srl, Roma, Italy). Gait variability was measured by an electronic walkway (GAITRite™). Participants were divided into groups based on fall history (fallers and non-fallers). Differences between groups in terms of energy expenditure measures and gait variability metrics were determined by the analysis of variance test. The relationship between gait variability and energy cost of walking was examined by the Pearson's correlation coefficient test. ResultsThirty-three PwMS were classified as fallers and 55 as non-fallers. Non-significant differences between groups were observed in the energy expenditure measures, including cost of walking. Fallers demonstrated higher step length variability compared with non-fallers (4.58 (S.D. = 2.42 vs. 3.40 (S.D. = 1.40); p-value = 0.005). According to the Pearson's correlation coefficient analysis, a significant relationship was found between step length variability and energy cost of walking in the non-fallers group (Rho = 0.372, P-value = 0.006) and the total group (Rho = 0.296, p-value = 0.005), but not in those PwMS with a history of falls. SignificanceWe demonstrated a significant relationship between increased gait variability and energy expenditure while walking only in MS patients without a history of falls. This is important as there is evidence of the clinical relevance of increased gait variability, poor fitness level and high risk of falling in the MS population.

A review of energy-efficient scheduling in intelligent production systems

Recently, many manufacturing enterprises pay closer attention to energy efficiency due to increasing energy cost and environmental awareness. Energy-efficient scheduling of production systems is an effective way to improve energy efficiency and to reduce energy cost. During the past 10 years, a large amount of literature has been published about energy-efficient scheduling, in which more than 50% employed swarm intelligence and evolutionary algorithms to solve the complex scheduling problems. This paper aims to provide a comprehensive literature review of production scheduling for intelligent manufacturing systems with the energy-related constraints and objectives. The main goals are to summarize, analyze, discuss, and synthesize the existing achievements, current research status, and ongoing studies, and to give useful insight into future research, especially intelligent strategies for solving the energy-efficient scheduling problems. The scope of this review is focused on the journal publications of the Web of Science database. The energy efficiency-related publications are classified and analyzed according to five criteria. Then, the research trends of energy efficiency are discussed. Finally, some directions are pointed out for future studies.

Energy Cost of Running Under Hypogravity in Well-Trained Runners and Triathletes: A Biomechanical Perspective

Abstract Hypogravity treadmills have become a popular training tool in distance running and triathlon. Counter-intuitively, tibial acceleration load is not attenuated by hypogravity unloading during running, while, equally surprisingly, leaps become flatter instead of higher. To explain these effects from a biomechanical perspective, Polet, Schroeder, and Bertram (2017) recently developed an energetic model for hypogravity running and validated it with recreational athletes at a constant jogging speed. The present study was conducted to refine that model for competitive athletes at relevant running speeds of 12–22 km h−1 and gravity levels of 100 %, 80 % and 60 %. Based on new experimental data on 15 well-trained runners in treadmill tests until volitional exhaustion, the enhanced semi-empirical model well describes energy expenditure and the observed biomechanical effects of hypogravity running. Remarkably, anaerobic contributions led to an increase in energy cost per meter for speeds above 16–18 km h−1 (p < 0.001), irrespective of hypogravity unloading. Moreover, some converging trends were observed that might reflect general adaptations in running motor control for optimization of efficiency. In essence, the outcome of this research might help sports scientists and practitioners to design running programs for specific training stimuli, e.g. conditioning of anaerobic energy metabolism.

Determining the Optimized Hub Height of Wind Turbine Using the Wind Resource Map of South Korea

Although the size of the wind turbine has become larger to improve the economic feasibility of wind power generation, whether increases in rotor diameter and hub height always lead to the optimization of energy cost remains to be seen. This paper proposes an algorithm that calculates the optimized hub height to minimize the cost of energy (COE) using the regional wind profile database. The optimized hub height was determined by identifying the minimum COE after calculating the annual energy production (AEP) and cost increase, according to hub height increase, by using the wind profiles of the wind resource map in South Korea and drawing the COE curve. The optimized hub altitude was calculated as 75~80 m in the inland plain but as 60~70 m in onshore or mountain sites, where the wind profile at the lower layer from the hub height showed relatively strong wind speed than that in inland plain. The AEP loss due to the decrease in hub height was compensated for by increasing the rotor diameter, in which case COE also decreased in the entire region of South Korea. The proposed algorithm of identifying the optimized hub height is expected to serve as a good guideline when determining the hub height according to different geographic regions.

Evaluation of selected cardiopulmonary and perceived exertion responses to four infant carrying methods utilised by African Mothers

Various infant carrying methods (ICMs) are utilised for childcare. Effects of these ICMs on the cardiopulmonary system are not known. This study evaluated cardiopulmonary and perceptual responses to four ICMs (back, front, side and in-arms) among 30 young females (18–35 years) while walking with a 6 kg simulated infant. Diastolic blood pressure (BP) responses were significantly different (p = .009) across the four ICMs, with the back ICM eliciting highest response. Heart rate, respiratory rate and systolic BP responses were not significantly different (p > .05) across the ICMs. Participants perceived the in-arms ICM as the most exerting. Body weight (p = .036) and body mass index (BMI) (p = .011) significantly correlated with systolic BP responses during the side ICM while age significantly (p = .036) correlated with heart rate changes during the in-arms ICM. Back ICM may pose more risk of diastolic BP dysfunctions. Increased body weight and BMI result in decreased systolic BP responses.IMPACT STATEMENTWhat is already known on this subject? Infant carrying (IC) has been associated with increased energy cost, biomechanical changes and musculoskeletal injuries. There is paucity of data on the cardiopulmonary responses to IC.What do the results of this study add? Back ICM resulted in higher responses in diastolic blood pressure. During the side ICM, participants’ systolic BP decreased with increasing body weight and BMI values. Increased age resulted to decreased heart rate responses during the in-arms ICM.What are the implications of these findings for clinical practice and/or further research? There is need for effective monitoring of the cardiopulmonary parameters during IC tasks, especially among women with cardiopulmonary dysfunctions. Women with diastolic dysfunctions should be discouraged from utilising the back ICM. It is necessary for further studies to evaluate infant carrying-related cardiopulmonary responses relative to various components of IC practices, including weight of infant, maternal anthropometric characteristics and duration of IC tasks during each infant carrying method.

Decreasing of Profile Air Drag to the Train Movement Inside the Tube Transport

Background: The movement of the train in an insulated space with the natural atmospheric pressure is accompanied by energy losses for unproductive work to overcome the profile air drag from the front and rear surfaces of the vehicle. At the same time, there is also a considerable increase of energy costs for overcoming the growing force of oncoming air drag. In order to exclude these energy losses, it is proposed to organize synchronous and volume-balanced pumping of air from the front part of the tube transport and injection of the air into the back part of the tube transport.
 Aim: To develop a method of organising air exchange inside the tube transport, which will ensure the reduction of air resistance to the movement of the train.
 Methods: The proposed developments are based on well-known national and foreign designs of high-speed tube transport systems, the results of a comparative analysis of tube transport with varying degrees of air pumping (backing vacuum and hard vacuum), taking into account the experience of redistributing the residual air volume in the Hyperloop and TransPod tube transport systems. The operating parameters of the compressor units that pump air into the internal cavity of the tube when the train is in motion is regulated on the basis of process models of gas dynamics.
 Results: A new method and device has been developed for reducing the air drag to the movement of the train by forced air exchange, which provides for the redistribution of air from the front to the rear of the transport tube relative to the vehicle travel direction. For the air redistribution, the external air exchange unit, consisting of air ducts, compressor units, gate valves, and air collectors is used. The process of external air exchange takes place only when the vehicle is in motion, for the movement of the vehicle no prior air exhaust is required. The air redistribution is controlled taking into account the speed of the train, its location in the tube, the design features of the tunnel and vehicle. The speed of the train for each segment of the speed section is normalised depending on the actual performance of the components of the air exchange system. Modes of operation of the compressor units must ensure synchronous redistribution of air from the front to the rear of the tube. The movement of a vehicle along a tube with normal atmospheric pressure in the internal cavity provides conditions for the safe transportation of goods and passengers.
 Conclusion: The developed method is designed to reduce the force of air resistance when the train is in motion inside the airtight tube without creating vacuum. The presented developments have good prospects for use in projects of high-speed transport systems of both underground and underwater designs.

Assessment of Battery Storage Technologies for a Turkish Power Network

Population growth has brought an increase in energy demand and cost that has a meaningful impact on personal and government expenses. In this respect, governments attach importance to investments in renewable energy resources (RER), which are a sustainable and clean energy source. However, the unpredictable characteristics of RER are a major problem for these clean sources and RER need auxiliary assets. Battery energy storage systems (BESS) are one of the promising solutions for these issues. Due to the high investment cost of BESS, governments act cautiously about accepting and implementing BESS in their power network. Recently, with the improvement of technology, the cost of BESS has been reduced, and therefore battery technologies have begun to be applied to conventional systems. In this study, first, we will review and discuss the current globally state-of-the-art BESS and their applications. Later, attention will be turned to a country-specific study for Turkey.

Optimization of a SAG Mill Energy System: Integrating Rock Hardness, Solar Irradiation, Climate Change, and Demand-Side Management

Integration of renewable energy into mining and processing operations is becoming necessary as part of a strategy towards sustainability in the minerals industry. A solar photovoltaic plant along with a battery energy storage system (PV-BESS) can provide a long-term solution to cope with increasing energy costs, thus reducing the tension with other societal competing needs for a key resource such as clean energy. However, sizing these systems is challenging, in face of uncertain ore grindability and solar power availability. In this paper, we present an application of an integrated model to size the PV-BESS, where the variability of ore grindability is modeled using geostatistical tools, solar irradiance variability is captured using a Markov chain simulation model, and the entire system is optimized through linear stochastic optimization, considering a fixed mine schedule for the feed of a semiautogenous grinding (SAG) mill. The main goals are to minimize the costs associated with operating the SAG mill in the presence of a PV-BESS system, understand how the sizing and costs change under the influence of stochastic drivers, and reveal the potential for demand-side management in mines. The size and costs of the necessary infrastructure are determined for a model of estimated grindability and an ensemble of 50 simulated models of grindability, and compared against the sizing and cost of the ground truth. The effect of climate change on solar energy availability is accounted for by forecasting the ratio of excellent, good, and moderate days over bad days in terms of irradiance out to the year 2030. Finally, the effects of stockpiles and feed control according to the processing plant needs, namely a demand-side management approach, are evaluated to reveal the impact on the energy requirements and the sizing of the photovoltaic and storage system. The model is optimized considering a yearly cost function, with hourly resolution for the solar irradiance and hardness models. The results show that integrating solar power into the operation of a SAG mill has potential to reduce the total energy cost by 27%. Robustness against climate change can be achievedwith an increase in total cost of 1%. Finally, use of stockpiles to manage the ore supply to the mill and minimize the energy cost to process it results in a cost reduction of around 2%, which should offset the rehandling cost of managing the stockpiles.

Thermal Resistance and Condensation in the Light-frame Timber Wall Structures with Various Composition of Insulation Layers

As energy costs increase, more people has become interested on energy efficiency and savings in residential buildings. The two main subjects related to energy in residential buildings are insulation and condensation. There are two approaches to prevent condensation; increasing air tightness and maintaining the temperature inside of the wall structure over the dew point, which is in turn related to insulation. Even though the Korean government has highlighted the importance of energy efficiency for residential housings, and in spite of the customers’ demands, the timber construction industry is still using conventional light-frame construction without even trying to improve energy efficiency. In this study, various types and combinations of wall structures were tested under cold outdoor and warm indoor temperatures to analyse the temperature gradients and to determine the possible sites of condensation in the wall structures. In addition to the experimental tests, three theoretical models were developed and their estimations of temperature change through the wall structure were compared with the actual measurements to evaluate accuracy of the models. The results of the three models agree relatively well with the experimental values, indicating that they can be used to estimate temperature changes in wall structures. The theoretical analysis of different insulation layers’ combinations show that condensation may occur within the mid-layer in the conventional light-frame wall structures for any combination of inner-, mid-, and outer-layers of insulation. Therefore, it can be concluded that the addition of an inner and outer insulation layer or increasing the thickness of insulation may not be adequate to prevent condensation in the wall structure without preventing penetration of warm moist air into the wall structure.

Determination of pollutant emission of electric vehicle in real traffic conditions in Poland

Alternative drives have an increasing share in the global, European and Polish market. The city authorities support primarily the de-velopment of electromobility. Progress in these issues is also noticeable in Poland. The increasing number of battery electric vehicles (BEVs) requires increasing energy costs of the country. Therefore, it is necessary to increase energy production. This work estimates how large this energy surplus should be. For this purpose, it was necessary to deter-mine the average energy consumption of an electric vehicle in real traffic conditions, and then to calculate the average energy demand for a selected number of vehicles. Obtained results were related to pollutant emission considered in the well-to-wheel perspective (in-cluding generation of electricity). In the article, the authors also referred to the minimum number of charging stations for electric vehicles on the Trans-European Transport Network (TEN-T) in Poland. This is a necessary condition on which depends the use of BEV vehicles not only on the territory of cities, but also throughout the country.