Over the past few decades, domestic water consumption in residential areas has declined significantly. This reduction can be attributed to several factors, including the widespread implementation of individual metering, rising water prices, development of more water-efficient sanitary fixtures, and an increased public awareness of water scarcity. However, there’s a growing concern that plumbing designers may be inadvertently oversizing pipe installations for domestic water due to reliance on outdated design manuals and standards that promote overly conservative methods. Traditionally, the primary standard for dimensioning domestic water pipes in Denmark has been to ensure that the installation can deliver the required water flow rate in 99.9% of outlet usage instances. To investigate this issue further, a recent project conducted by the Department of the Built Environment at Aalborg University, on behalf of The Danish Authority of Social Services and Housing, involved measuring the domestic water flow in eight multi-story apartment buildings. The findings revealed that, on average, the investigated pipe installations were oversized by a factor of 2-3. This general oversizing results in an extended retention time for domestic water within the pipes, which poses risks such as the growth of Legionella bacteria—an increasingly prevalent issue not only in Denmark. Practical application The study contributes to determine whether there was indeed an oversizing of the water pipe installation, as this could potentially lead to various adverse consequences. The conclusion based on the performed flow measurements was that the guideline for designing domestic water distribution pipes in general significantly oversized both hot and cold pipes. Two proposals that reduces the design flow rate by 25% and 50% was therefore developed to update the national Danish standard DS 439 and during 2023 it was finally agreed in the standardization committee to implement the proposal for a reduction of 25%.

In smart buildings, elevator faults may affect the traveling efficiency and the safety of passengers. It is important to find a quick and accurate method for fault diagnosis to minimize disruption time. Most existing fault diagnosis methods are for gear systems, which ignore the characteristics of elevators and need adaptations before applying them to the elevators. This study presents a novel multidomain feature extraction method for elevator fault diagnosis. It calculates the time domain features and wavelet packet energy and then extracts the elevator frequency features. These multidomain features are utilized as the input of a support vector machine to diagnose elevator faults. Subsequently, SHapley Additive exPlanations is used to select features to remove redundant features without reducing diagnosis accuracy. Comparative experiments show that multidomain feature extraction based on triaxial data improves diagnosis accuracy. Additionally, the elevator frequency feature extraction method further enhances diagnosis accuracy. In addition, experiments demonstrate that SHapley Additive exPlanations feature selection can be effectively applied to remove redundant features in different fault diagnoses, which improves the training efficiency and reduces the risk of overfitting. Practical applications In this paper, we present a practical solution for elevator fault diagnosis in intelligent buildings. By the proposed method, maintainers can find elevator faults based on objective evidence rather than intuitive feeling. We utilize a phone instead of the vulnerable and expensive equipment to collect and analyze signals, which makes the cost for this solution inexpensive and propagable. Thus, this solution can be applied to most practical elevator maintenance to reduce the elevator downtime.

This study reviews Soft Landings (SL) implementations, focusing on its role in achieving Low and Net Zero Emission (LZE) buildings and reducing the energy performance gap. With buildings contributing significantly to global carbon emissions, it is crucial to understand the effect of integrating approaches like SL for meeting Net Zero goals. Notably, this research identified that the extended 3-year aftercare phase of SL does not always lead to reduced operational carbon emissions. While SL promotes collaboration and structured delivery, its overall impact on consistently achieving LZE buildings remains unclear, largely due to insufficient in-use performance data. The paper advocates for integrating SL with other performance-based methods, emphasising the need for enhanced industry collaboration and data sharing to augment the understanding and effectiveness of SL in delivering LZE buildings. Practical Application: This paper offers a thorough analysis of the Soft Landings (SL) framework in achieving Low and Net Zero Emission (LZE) buildings. It examines barriers at each project lifecycle stage and evaluates SL’s effectiveness through case studies, revealing inconsistencies in reducing operational emissions. The findings emphasise integrating SL with performance-based initiatives and enhancing industry collaboration and data sharing. Built environment professionals can leverage these insights to improve project delivery, optimise building performance, and achieve LZE goals more effectively.

This article evaluates the performance of a 20 MW grid-connected photovoltaic system installed in the Naama region, southwestern highlands of Algeria. The production database used in this work was recorded between January 1, 2017, and December 2022, from the plant’s SCADA system. During the first 5 years of production, the final yield varied from 3.88 in winter 2020 to 6.30 h/day in summer 2017, while the reference yield varied from 4.45 to 7.05 h/day, the annual average performance ratio is equal to 83.35%, and the annual average capacity factor was found to be 20.05% for the monitored period. These data are then compared with the predicted outcomes by a detailed difference analysis using three widely used PV simulation tools: PVsyst, SAM, and PVSol. Results indicate that the actual data strongly coincide with those predicted by the PVsyst simulation, as confirmed by statistical indices. However, the degradation of the PV plants over the monitored period is quantified using a linear model and a CSD model and is estimated at −1.43 and −1.55 %/year, respectively. In summary, the photovoltaic system performance indices obtained are satisfactory compared to large-scale photovoltaic systems reported in other studies. Practical applications This study evaluates the performance and degradation of a 20 MWp photovoltaic system located in the highlands of Algeria. The results of this article will serve as a baseline for the future construction of PV plants to raise awareness among decision-makers about the beginnings of the deterioration of installations to allocate a budget for the maintenance and operation of these installations. The findings of this study have the potential to contribute to the wider adoption of Photovoltaic systems as a viable alternative to traditional energy in Algeria and especially in the Highlands.

Previous studies have shown a strong relationship between heat-related fatalities and ambient air temperature. This problem is expected to increase due to constant urbanization and the threat of global warming. Therefore, designing urban street canyons (USC) to be thermally comfortable is essential for a healthy urban life. This paper investigates the correlation between an urban street canyon’s aspect ratio and the albedo material of its surrounding buildings. The aim is to study which combination can successfully mitigate urban heat stress and create a thermally comfortable pedestrian microclimate. This research uses a comparative analysis that suggests the optimum albedo for different USC geometries. An ENVI-met model was used to simulate 9 scenarios for an idealized 2D USC with varying aspect ratios and albedo values. Air temperature, mean radiant temperature and Universal Thermal Climate Index (UTCI) were analyzed. Results show that a medium albedo value performs best thermally in all USCs. High albedo had 13.2% more combined thermal stress compared to medium albedo. However, high albedo performed much better in deep canyons than wider ones, with the average UTCI decreasing by about 4.8%-5.7% when used in deep canyons. Medium albedo should be exclusively used in wide canyons for minimal thermal stress. Practical application: This study provides a reference to the use of materials in urban street canyons of different aspect ratios to achieve good outdoor thermal comfort for pedestrians.

In this study, a clean workshop is the subject of our research study, and computational fluid dynamics methods are applied to investigate the effect of exhaust pipe height, exhaust velocity, barrier structure, and wind direction on contaminant diffusion from the clean workshop. Results show that an increase in exhaust pipe height and exhaust velocity or a decrease in barrier height can effectively reduce the pollutant concentration at each fresh air inlet (FAI). Along the wind direction, the contaminant concentration initially increases and then decreases as distance increases. When the height of the exhaust pipe reaches 45 m, the effect of pollutants on the FAI is insignificant. When the exhaust velocity reaches 12 m/s, the effect of pollutants on the FAI weakens as the emission speed of flue gas increases. Reducing the height of the barrier to 29–31 m can effectively improve the concentration of pollutants at each FAI. Practical implications The mechanism by which the exhaust pipe height, exhaust velocity, barrier structure, and wind direction affect pollutant diffusion from a clean room workshop is systematically investigated by combining the CFD methods with an actual clean workshop as the research object, and the optimal pollutant reduction conditions are presented, thus providing scientific guidance for the construction of clean plants and the reduction of pollutant emissions.

The smoke back-layering length is a crucial parameter for evacuating people in both road and subway tunnel fires. This study investigates the fire hazard induced by carriage fire in inclined metro tunnels under natural ventilation. The parameter ‘transition slope’ is defined to measure the smoke flow from the carriage head in the upstream direction to the tunnel or not due to the stack effect of the tunnel slope. The aim of this paper is to analyse the effects of changes in cross-section, downstream length, tunnel slope, and carriage side-door coupling on smoke behaviour characteristics by experiment and simulation methods. A piecewise function expression between dimensionless smoke back-layering length, downstream length, and tunnel slope for carriage fires in an inclined tunnel under natural ventilation is proposed by theoretical analysis. At the same time, a 1:15 scale model experiment was conducted to initially analyse the characteristics of smoke movement. Following this, full-scale numerical simulations were employed to complement the model experiment and quantify the principles governing smoke movement. The experimental results show that the tunnel slope has a significant effect on the smoke back-layering length. In contrast, the influence of the heat release rate was found to be relatively minor. In addition, simulation results show that the tunnel slope has no significant effect on the smoke back-layering length when the fire location is approximately 20 m from the train head, and the tunnel slope is in the range of 2.29° ∼ 3.43° (4% ∼ 6%). For small tunnel slopes, smoke spreads in the tunnel, and the smoke back-layering length produced by the virtual fire source shows a different law from the previous study model. Finally, the correlation coefficient of the piecewise function in theoretical analysis is fitted by combining the experimental and numerical simulation results. Practical application This study provides valuable insights into the practical implications of controlling and mitigating the impact of fires in inclined metro tunnels. By understanding the critical role of tunnel slope and providing a quantitative tool for smoke spread law assessment, this study contributes to the enhancement of safety measures and the protection of lives in tunnel environments during fire incidents.

This study employed FLUENT to analyse smoke movement and temperature distribution in an evacuation corridor with varying blockage ratios, focusing on the subway tunnel section of Fuzhou Metro Line 4. The simulation results revealed that under natural ventilation condition, the smoke spread area in the evacuation corridor is significantly greater for the high blockage ratio tunnel than for the low blockage ratio tunnel in the tunnel’s length direction, and the entire temperature distribution in the tunnel’s height direction is also high. Following the introduction of longitudinal ventilation, smoke spread in the evacuation corridor and the tunnel ceiling upstream of the fire source are effectively controlled, with smoke suppression movement in the evacuation corridor being significantly faster than that near the tunnel ceiling. As ventilation time increases, the back-layering length of smoke in the evacuation corridor gradually shortens. Within 150 s of ventilation, the critical safety distance below the safety temperature for a low blockage ratio is shorter than that for a high blockage ratio tunnel. In conclusion, longitudinal ventilation increases the cooling rate of high-temperature smoke in a high blockage ratio tunnel, but the influence of high ventilation velocity on evacuation cannot be ignored.Practical applicationThis study provides recommendations for the evacuation plan and procedures under longitudinal ventilation. It is advisable to consider lowering the height of the evacuation corridor in the tunnel from the rail surface, thereby creating a more extensive safety space for personnel evacuation. Additionally, the implementation of prominent marks and voice prompts in the upstream area of the fire outbreak is crucial. This ensures that personnel are directed to evacuate from the upstream section during emergency situations.

Data-driven artificial neural networks (ANN) based on data drivers with their powerful self-learning capability and high adaptability are gaining increasing attention for the application in modeling indirect evaporative coolers (IEC). However, most ANN models of IEC in existing studies are either limited to a specific climate region or conventional IEC configurations. In this paper, a multi-region back-propagation (BP) neural network model for predicting the performance of advanced dew-point IECs is developed. Operational data for ANN model development were collected through field measurements in IEC projects in three typical climate zone cities in China (Dunhuang, Yulin, and Fuzhou), covering arid, moderately wet, and humid regions. A comparative study of three single-region neural network models was conducted in terms of both convergence characteristics and statistical performance metrics. Each model contains two input variables (inlet air temperature, inlet air humidity) and one output variable (wet-bulb efficiency). The results show that the model fits best in Yulin, followed by Dunhuang and Fuzhou, with total correlation coefficients of 0.9918, 0.9477, and 0.8946, respectively. The predicted values of wet-bulb efficiency are in good agreement with the actual operating data, and the deviation of almost all predicted values is within ±10%. Practical application The application values of IEC ANN models are as follows. First, the IEC-ANN model can predict IEC performance adaptively based on dynamic operational data. Therefore, it can provide the best operating strategy and design parameters for different situations. In addition, it can provide a fast response to guide the system operation when auxiliary control is required. Most importantly, this new approach requires only a limited number of tests rather than exhaustive experimental studies or dealing with complex mathematical models, and future manufacturers can use neural network technology to evaluate the performance of dew-point indirect evaporative coolers, thus saving engineering budget and time.