Search Results (92)

Traditional air conditioning consumes substantial electricity, exacerbates the urban heat island effect, and creates a maladaptive feedback loop, necessitating a shift toward passive-first net-zero pathways. This study takes a typical six-story residential building in Nanjing’s hot summer and cold winter climate zone as a case study. Using EnergyPlus hourly simulations, three progressive passive strategy packages are designed to quantify the impact of building envelope heat exchange on cooling loads, grid stress, and heat resilience. Package A includes external shading and natural ventilation. Package B adds reflective coating and a green roof. Package C further adds night ventilation precooling and high-performance windows. The results show that Package C achieves a 62.5% reduction in peak cooling load and a 63.0% reduction in seasonal cooling load. Daytime peak inward heat gain decreases from 68 W/m² to 22 W/m², while nighttime outward heat dissipation increases from 12 W/m² to 38 W/m². Under an extreme heat day of 41.2 °C with no active cooling, indoor peak temperature drops from 36.8 °C to 29.4 °C, and heat risk hours decrease by 73.6%. Peak-hour power demand is reduced by 70.4%, with a systemic leverage factor of 1.08. Innovations include achieving over 60% load reduction using only mature passive strategies, introducing the systemic leverage factor to quantify urban heat island mitigation benefits, and establishing a vulnerability-to-resilience transformation framework. The passive-first pathway validates building envelope as the first line of defense for net-zero futures. However, the findings are based on a typical six-story residential building in Nanjing and require validation through field measurements or broader application across different climate zones and building typologies before generalization. Full article

This study presents the design and performance evaluation of a hybrid solar-driven system (SOLIVE) that integrates tubular daylighting and buoyancy-driven natural ventilation within a single architectural component for industrial and large-scale buildings. While solar tubes and solar chimneys have been widely studied as independent passive technologies, their combined use in a unified system capable of delivering both daylight and ventilation remains largely unexplored. The proposed system utilizes solar tubes not only for transmitting natural daylight but also as thermal drivers that induce airflow through the stack effect generated by solar heating along the tube surface. A mathematical framework combining photometric daylight modeling and buoyancy-driven airflow analysis was developed to evaluate the system performance. Numerical simulations were conducted for three representative solar reference days (Equinox, Summer Solstice, and Winter Solstice). The influence of the key design parameters, including illuminated surface area (5–15 m²), solar tube diameter (0.1–0.3 m), and ventilated space volume (20–60 m³), was systematically analyzed. The results show that, under the adopted modelling assumptions, the system provides peak illuminance between 376 and 502 lux and ventilation rates up to 20.5 air changes per hour (ACH). These values are discussed as indicative benchmarks with respect to ISO 8995-1 and ASHRAE 62.1, rather than as proof of full real-building compliance, since glare, illuminance uniformity, thermal comfort, occupancy, wind effects and HVAC integration were not fully modelled. These findings demonstrate the potential of the proposed system as an effective passive solution for improving indoor environmental quality and reducing building energy demand in sunny climates. Full article

This study develops an interpretable machine learning (ML) surrogate to predict hourly indoor air temperature and discomfort indicators for a representative Mexican social-housing prototype in San Luis Potosí (cold semi-arid, Köppen–Geiger BSk). A four-zone EnergyPlus model with constant window opening (50%) and no internal gains was used to generate a parametric dataset spanning 24 building orientations, seven roof solar absorptance levels, and two neighborhood configurations (surrounded vs. corner). Zone-specific bagged-tree regression models were trained in MATLAB using weather predictors, temporal indicators, and weather-memory features (including outdoor temperature lags and rolling averages). Orientation and roof absorptance were included as explicit design predictors, enabling the surrogate model to generalize across the full combinatorial design space rather than requiring a separate model for each configuration. Interpretability was assessed with SHAP values. Evaluated on orientation–absorptance combinations deliberately held out during training, the surrogate achieved high accuracy across zones of the house (R² = 0.98–0.99; RMSE = 0.31–0.67 °C) with stable, near-zero-centered residuals. When propagated into adaptive-comfort metrics computed directly relative to the monthly neutral temperature $T_n$, ML predictions preserved the main cold and hot discomfort degree-hour patterns across the full design space. The proposed surrogate enables rapid, physically consistent comfort-oriented screening of roof finishes and orientation choices in naturally ventilated social housing. Full article

Climate change poses severe threats to cultural heritage, yet thermal performance impacts on traditional architecture in conflict-affected regions remain poorly quantified. This study provides one of the first comprehensive assessments of climate change effects on UNESCO World Heritage architecture in Yemen’s Old City of Sana’a. We employed building energy simulation (DesignBuilder/EnergyPlus) to evaluate the thermal performance of a representative five-story traditional adobe tower house under three climate scenarios: baseline (1974–2017), SSP2-4.5 (moderate emissions, 2041–2060), and SSP5-8.5 (high emissions, 2041–2060). Climate projections were derived from five CMIP6 models using the morphing methodology, with natural ventilation-only operation (no mechanical cooling). The results demonstrate dramatic thermal performance degradation: annual overheating hours (>30 °C) increase more than 10-fold from 111 h (baseline) to 1264 h (SSP2-4.5) on the most vulnerable floor, representing escalation from 1.3% to 14.4% of the year. Extreme heat exposure (>32 °C) emerges under climate scenarios (324–423 h annually) and is absent under baseline conditions. Thermal comfort declines 27–30 percentage points across all floors. The findings reveal the systematic failure of passive cooling mechanisms under elevated temperatures, particularly when nighttime temperatures exceed 20 °C, eliminating nocturnal heat purging opportunities. The results necessitate the urgent development of heritage-sensitive adaptation strategies for Old Sana’a and similar UNESCO sites in arid regions facing compound climate-conflict vulnerability. Full article

This paper investigates summertime indoor overheating in naturally ventilated public buildings located in a cool temperate Baltic climate, where buildings are traditionally designed for heating-dominated conditions. The study is based on long-term field measurements conducted in two naturally ventilated rooms (a school classroom and a physician’s consultation office) and aims to quantify indoor overheating and examine indoor–outdoor thermal relationships. Indoor air temperature was continuously monitored and analysed together with concurrent outdoor air temperature and global solar radiation data. Overheating was assessed using fixed temperature thresholds (26 °C and 28 °C), exceedance hours, degree-hours, diurnal distributions, and indoor–outdoor temperature correlations; adaptive comfort criteria were not applied. The results reveal a pronounced contrast between the two spaces. The classroom experienced frequent and severe overheating and strong coupling to outdoor air temperature (R² = 0.60), whereas the physician’s office exhibited limited exceedance and a more buffered thermal response, with weaker indoor–outdoor coupling (R² = 0.32). These findings indicate substantial room-to-room variability in overheating behaviour, even under the same climatic conditions. While derived from a limited two-room case study, the results suggest that room-level assessment may be valuable for identifying overheating risks in naturally ventilated public buildings in cool-climate regions. Full article

Hospitals are major consumers of natural resources, and their continuous 24/7 demands exert significant environmental repercussions. Notably, energy utilization and waste generation constitute primary determinants of the ecological footprint associated with healthcare facilities. This study aims to provide a replicable framework for estimating operational carbon account of orthopedic hospital operations using readily available data, without requiring expert-level life cycle assessment tools. A three-level analysis was applied to a case study in a large Italian public hospital, focusing on CO₂e emissions from energy consumption and hazardous waste generation. Operational data from the hospital and detailed audits of orthopedic procedures were used to estimate energy consumption, ventilation loads, and waste volumes. Results showed that HVAC systems dominated energy-related emissions, while surgical waste was a major contributor at the meso- and micro-levels. Several mitigation strategies were proposed, including reducing off-hours air exchange rates and improving waste segregation, leading to potential emission reductions. The study highlights that even a simplified carbon accounting approach can generate valuable insights for healthcare managers, supporting internal benchmarking and sustainability action. Full article

This study develops an explainable reinforcement learning (RL) control framework for hybrid ventilation in Mediterranean office buildings to enhance thermal comfort, energy efficiency, and long-term climate resilience. A working environment was created Using EnergyPlus to represent an office test cell equipped with natural ventilation and air conditioning. The RL controller, based on Proximal Policy Optimization (PPO), was trained exclusively on present-day Typical Meteorological Year (TMY) data from Beirut and subsequently evaluated, without retraining, under future 2050 and 2080 climate projections (SSP1-2.6 and SSP5-8.5) generated using the Belcher morphing technique, in order to quantify robustness under projected climate stressors. Results showed that the RL control achieved consistent, though moderate, annual HVAC energy reductions (6–9%), and a reduction in indoor overheating degree (IOD) by about 35.66% compared to rule-based control, while maintaining comfort and increasing natural ventilation hours. The Climate Change Overheating Resistivity (CCOR) improved by 24.32%, demonstrating the controller’s resilience under warming conditions. Explainability was achieved through Kernel SHAP, which revealed physically coherent feature influences consistent with thermal comfort logic. The findings confirmed that physics-informed RL can autonomously learn and sustain effective ventilation control, remaining transparent, reliable, and robust under future climates. This framework establishes a foundation for adaptive and interpretable RL-based hybrid ventilation control, enabling long-lived office buildings in Mediterranean climates to reduce cooling energy demand and mitigate overheating risks under future climate change. Full article

This paper presents research on a naturally ventilated room with a façade opening covered by openwork grating. The first part describes experimental measurements of airflow velocity through the façade opening. Then, a numerical model of the room with the opening is introduced and validated using the experimental data. The core of the research consists of a series of numerical simulations in which the inflow and outflow of air are determined hour by hour using official data from a typical meteorological year and statistical climatic data for building energy calculations. Among the findings is a strong dependence of the opening performance on the façade orientation and the season of the year. For almost the entire year, excluding the daytime in July, the average ambient temperature is lower than the assumed inner temperature, which can cause heat losses due to air exchange (solar irradiation is not taken into account). The highest heat losses, close to 10 kW per window slot for all façades, are expected in February. The analysis confirms that, in temperate climates, natural ventilation is beneficial, especially when utilizing night cooling. The energy savings for a single window slot in July may reach up to 0.012 kWh/m². Full article

In response to global climate change, harnessing the climate-adaptive wisdom of vernacular dwellings is crucial for sustainable architectural design. This study takes Haiyan Village in the Kunming plateau area as a case study, focusing on three typical vernacular dwelling types of Yikeyin—‘Half seal’, ‘One seal’, and ‘Two seals’. Using Ladybug and Honeybee within the Rhino Grasshopper platform, a quantitative comparative analysis was conducted to evaluate their natural ventilation efficiency (characterized by Air Changes per Hour, ACH) and indoor thermal comfort (characterized by Predicted Mean Vote, PMV, and Predicted Percentage of Dissatisfaction, PPD). The results indicate the following: (1) Throughout the year, the ‘Two seals’ dwelling type exhibits the most stable diurnal temperature variation, while the ‘Half seal’ dwelling type shows the greatest fluctuation in its diurnal temperature range. (2) The summer ACH values for ‘Half seal’, ‘One seal’, and ‘Two seals’ dwelling types are 3.8~4.5, 1.5~2.9, and 0.8~1.6, while the winter values are 1.9~2.6, 1.3~1.8, and 0.7~1.0. The ventilation efficiency in summer is generally higher than that in winter, and it shows a significant decreasing trend as building volume increases. (3) The summer PPD values for ‘Half seal’, ‘One seal’, and ‘Two seals’ dwelling types are 12%, 18%, and 35%, while the winter values are 22%, 15%, and 12%. (4) The ‘One seal’ dwelling type exhibits good ventilation and thermal comfort throughout the year. The ‘Half seal’ demonstrates the best ventilation and thermal comfort in summer but poorer thermal comfort in winter. The ‘Two seals‘ dwelling type achieves the best thermal comfort in winter, but lower ventilation efficiency, while in summer, both thermal comfort and ventilation are poor. This study not only addresses the gap in the quantitative assessment of climate adaptability in vernacular dwellings but also provides critical data support and a theoretical basis for the scientific preservation, adaptive renewal, and sustainable inheritance of vernacular architecture in the context of climate change. Full article

For sustainable greenhouse design, natural ventilation is a vital component; it depends on the local climate. Therefore, optimizing the greenhouse orientation and vent opening configuration is a critical issue that needs to be addressed for a specific location (e.g., the central region of Saudia Arabia). Experiments were conducted in winter, in a curved-roof, single-span, N-S oriented greenhouse that includes roof and side-wall vents. Five different vent opening arrangements were examined. The outside and inside greenhouse environmental parameters were measured, and the ventilation rate (kg·s⁻¹) and the number of air exchanges per hour (N_a) were estimated for each opening case using a modified energy balance equation. The results showed that the common wind directions are N-S and NW-SE. For effective ventilation, greenhouses should be oriented in the E-W or NE-SW directions. Opening the side-wall vents exhibited the highest wind-driven ventilation rate that is essential to control temperature and humidity at the crop level, while only opening the roof vents is not recommended. In the central region of Saudi Arabia, natural ventilation is sufficient for operating greenhouses (${\overline{N}}_a$ > 30). Opening the roof and side-wall vents (combined wind and buoyancy effects) is the most efficient as long as the greenhouse axis is aligned perpendicular to the wind direction. Such information is essential for sustainable greenhouse management in an arid environment. Full article

Natural ventilation could be established as an effective passive design strategy for increasing air changes per hour in a built environment. Modern air conditioning systems often fail to provide sufficient fresh air, potentially causing health issues for occupants. In contrast, natural ventilation offers an effective alternative for maintaining sufficient indoor air quality in buildings. This study explores the application of grouped airfoil arrays on building façades as an innovative passive design to enhance the air change rate. Numerical simulations were conducted to analyze various airfoil configurations, determining the most effective design for building a façade. Three groups, including symmetrical, semi-symmetrical, and flat-bottomed grouped airfoils, were selected according to their aerodynamic properties and potential impacts on airflow dynamics. For this purpose, a typical high-rise residential building was selected as a case study for field measurement and CFD simulation. The results indicated that symmetrical airfoil arrays could increase the air changes per hour (ACH) up to 23 times per hour with a wind velocity of 0.37 m/s at 10 m above ground, whereas their bidirectional performance ensured stable airflow regardless of wind direction. Although semi-symmetrical airfoil arrays maximize air capture and induce beneficial turbulence, the ACH within a residential unit was boosted up to 16 times per hour under the same outdoor wind velocity conditions. The ACH was 14 times per hour for the flat-bottom airfoils, serving as a comparative baseline and providing insights into the performance advantages of more complex designs. Full article

This paper evaluates the effectiveness of natural ventilation as a health and safety strategy in municipal buildings, focusing on its capacity to ensure indoor air quality and limit airborne disease transmission. Natural ventilation can be incorporated into building design as the primary mechanism for achieving the required indoor air quality, equipping buildings with operable windows based on their intended occupancy. Using 11 public buildings in Mostoles, Spain, as case studies, the research applies a quantitative methodology based on carbon dioxide concentration to estimate ventilation rates and theoretical occupancy thresholds. The findings reveal that cross ventilation is the only natural method capable of meeting air renewal rates recommended by health authorities, particularly the IDA2 air quality standard and three to five air changes per hour suggested to reduce disease spread. However, 53% of the assessed spaces lacked cross ventilation capacity, underscoring the need to integrate natural and mechanical systems. The study proposes a replicable model to assess and adapt indoor occupancy based on real ventilation capacity, offering a practical tool for decision-making in public health, energy efficiency, and architectural design. Ultimately, the research supports the strategic use of natural ventilation as a low-cost, scalable intervention to enhance environmental quality in public facilities. Full article

Under the dual challenges of global energy crisis and climate change, the building sector, as a major carbon emitter consuming 33% of global primary energy, has seen its energy efficiency optimization become a critical pathway towards achieving carbon neutrality goals. The Window-to-Wall Ratio (WWR), serving as a core parameter in building envelope design, directly influences building energy consumption, with its optimized design playing a decisive role in balancing natural daylighting, ventilation efficiency, and thermal comfort. This study focuses on the traditional One-Seal dwellings (Yikeyin) in Kunming, China, establishing a dynamic wind field-thermal environment coupled analysis framework to investigate the impact mechanism of window dimensions (WWR and aspect ratio) on indoor thermal comfort under natural wind conditions in transitional climate zones. Utilizing the Grasshopper platform integrated with Ladybug, Honeybee, and Butterfly plugins, we developed parametric models incorporating Kunming’s Energy Plus Weather meteorological data. EnergyPlus and OpenFOAM were employed, respectively, for building heat-moisture balance calculations and Computational Fluid Dynamic (CFD) simulations, with particular emphasis on analyzing the effects of varying WWR (0.05–0.20) on temperature-humidity, air velocity, and ventilation efficiency during typical winter and summer weeks. Key findings include, (1) in summer, the baseline scenario with WWR = 0.1 achieves a dynamic thermal-humidity balance (20.89–24.27 °C, 65.35–74.22%) through a “air-permeable but non-ventilative” strategy, though wing rooms show humidity-heat accumulation risks; increasing WWR to 0.15–0.2 enhances ventilation efficiency (2–3 times higher air changes) but causes a 4.5% humidity surge; (2) winter conditions with WWR ≥ 0.15 reduce wing room temperatures to 17.32 °C, approaching cold thresholds, while WWR = 0.05 mitigates heat loss but exacerbates humidity accumulation; (3) a symmetrical layout structurally constrains central ventilation, maintaining main halls air changes below one Air Change per Hour (ACH). The study proposes an optimized WWR range of 0.1–0.15 combined with asymmetric window opening strategies, providing quantitative guidance for validating the scientific value of vernacular architectural wisdom in low-energy design. Full article

The present study was motivated by the need to enhance indoor air quality and reduce airborne disease transmission in dense urban environments where high-rise residential buildings face challenges in achieving effective natural ventilation. The problem lies in the lack of scalable and convenient tools to optimize natural ventilation rate, particularly in urban settings with varying building heights. To address this, the scientific technique developed with an innovative metric, the urbanized natural ventilation effectiveness factor (uNVeF), integrates regression analysis of wind direction, velocity, air change rate per hour (ACH), window configurations, and building height to quantify ventilation efficiency. By employing a field measurement methodology, the measurements were conducted across 25 window-opening scenarios in a 13.9 m² residential unit on the 35/F of a Hong Kong public housing building, supplemented by the Hellman Exponential Law with a site-specific friction coefficient (0.2907, R² = 0.9232) to estimate the lower floor natural ventilation rate. The results confirm compliance with Hong Kong’s statutory 1.5 ACH requirement (Practice Note for Authorized Persons, Registered Structural Engineers, and Registered Geotechnical Engineers) and achieving a peak ACH at a uNVeF of 0.953 with 75% window opening. The results also revealed that lower floors can maintain 1.5 ACH with adjusted window configurations. Using the Wells–Riley model, the estimation results indicated significant airborne disease infection risk reductions of 96.1% at 35/F and 93.4% at 1/F compared to the 1.5 ACH baseline which demonstrates a strong correlation between ACH, uNVeF and infection risks. The uNVeF framework offers a practical approach to optimize natural ventilation and provides actionable guidelines, together with future research on the scope of validity to refine this technique for residents and developers. The implications in the building industry include setting up sustainable design standards, enhancing public health resilience, supporting policy frameworks for energy-efficient urban planning, and potentially driving innovation in high-rise residential construction and retrofitting globally. Full article

This study assessed the baseline indoor environmental quality (IEQ) of secondary school classrooms in Tanzania by measuring temperature, relative humidity, noise, lighting, and indoor air quality. Objective measurements were conducted using calibrated sensors in 14 classrooms across five schools, with data collected during occupied school hours and additional noise measurements during unoccupied periods. All classrooms are naturally ventilated through operable windows and doors. The findings reveal a pattern of cumulative IEQ deficiencies: classroom temperatures frequently exceeded the recommended 20–24 °C range, reaching means as high as 30.4 °C, while relative humidity varied widely, with levels occasionally surpassing 65%. Noise levels consistently exceeded the World Health Organization (WHO)’s recommended 35 dBA threshold, with significant differences observed between occupied and unoccupied periods (p = 0.02). Light distribution was uneven, with significantly higher lux levels near windows than at classroom centers (p < 0.001), and artificial lighting was generally insufficient due to infrastructure limitations. Although CO₂ concentrations remained below the 1000 ppm threshold, indicating adequate ventilation, particulate matter levels were often elevated, with PM2.5 reaching up to 58.80 µg/m³ and PM10 up to 96.90 µg/m³, exceeding health-based guidelines. Together, these findings suggest that students are exposed to multiple environmental stressors that may impair health, comfort, and academic performance. This study provides a critical baseline for future research and context-specific interventions aimed at improving learning environments in Tanzanian schools and similar settings in East Africa. Full article