With global warming and accelerated urbanization, building air-conditioning (AC) releases more heat into the environment, exacerbating the urban heat island (UHI) effects and increasing building cooling energy consumption. Existing research has limited quantification of the impact of air-conditioning anthropogenic heat (ACAH) on the cooling energy consumption of different types. This study aims to explore the distribution characteristics of ACAH and its impact on residential building energy consumption. Firstly, typical residential buildings in the Pearl River Delta region were selected as a case study. Field experiments were conducted to measure temperature and humidity at 0.5 m, 1 m, 2 m, and 3 m from the outdoor unit, alongside ambient temperature and wind speed. Three grid densities were applied to verify the CFD model, with a prediction error of less than 0.3 °C at 0.5 m under a medium grid. The simulated temperature at 1 m from the outdoor unit under calm wind conditions was compared with field measurements to reveal the horizontal and vertical distribution characteristics of ACAH. Secondly, the effects of different building shapes, ambient temperatures, and wind speeds on the spatial distribution of ACAH were investigated. Finally, EnergyPlus (V23.1.0) was employed as the building energy simulation software, with its microclimate coupling interface implemented via Python scripts to quantify cooling energy consumption variations across different building floors under ACAH influence. Results indicated that ACAH exhibits significant horizontal non-uniformity, exerting the greatest impact within a 0.5 m radius (affected air temperature 4.3 °C higher than ambient). Vertically, localized heat accumulation occurs in the building’s central area, with air temperature 3.5 °C higher than at the bottom. Furthermore, compared to fixed meteorological conditions, the cooling energy consumption difference across floors considering ACAH reaches approximately 7.8%. This study provides accurate meteorological boundary conditions for building energy assessment and supports microclimate management in residential areas.

Coupling equipment operation parameters with the hourly heat balance model, this study realized the integrated estimation of energy consumption and costs. Meanwhile, two typical greenhouse growth settings were investigated: one at an average temperature of 22.5 °C (25/20 °C and 30/15 °C) and another at 25 °C (35/15 °C and 30/20 °C). Based on the simulation results, in an average temperature of 22.5 °C, the target temperature of 30/15 °C is suggested, whereas in an average temperature of 25 °C, the target temperature of 30/20 °C is suggested. Moreover, two different electricity rate systems, mainly unit-form and time-of-use rates, were used to analyze the running costs of the greenhouse. Due to the energy demand, peaks often happened between 12:00 and 14:00, requiring the manipulation of mechanical environmental control strategies to keep the target temperature; the total electricity cost in time-of-use rates system was a little higher than that in unit-form rate. Results of the dry weights analysis suggest that the DIF30/20 scenario is more practical due to the substantial rise in electricity costs relative to its modest yield improvement for the others. This method achieved an RMSE of less than 2.7 °C for estimating summer greenhouse cooling energy consumption and can provide growers with quantitative temperature setting schemes during hot summers.

Rising global temperatures due to climate change are intensifying the cooling energy demands of critical infrastructure, including airports. This study assesses the impact of climate change on the cooling energy needs of five major international airports in Nigeria (Abuja, Enugu, Kano, Lagos, and Port Harcourt) using cooling degree days (CDDs) derived from the Coupled Model Intercomparison Project (CMIP6) multi-model ensemble climate projections. Monthly and annual CDD calculated with a base temperature of 18°C were obtained from the World Bank Climate Change Knowledge Portal (CCKP) at a spatial resolution of 25 km × 25 km. Percentage changes in CDD were analyzed for three future periods (2040–2059, 2060–2079, and 2080–2099) relative to the historical baseline (1995–2014) under moderate-( SSP2-4.5) and high-emissions (SSP5-8.5) pathways. Results indicate a consistent rise in CDD across all airports and future periods, with greater increases under SSP5-8.5. The highest CDD increases occur during peak summer months (June–August), straining cooling systems and infrastructure. Coastal airports like Lagos and Port Harcourt face significant absolute increases due to high baseline temperatures, while Kano exhibits the largest percentage changes, driven by its hot and dry climate. Late-century projections (2080–2099) show CDD increases exceeding 60% under SSP5-8.5, emphasizing the severe consequences of unmitigated emissions. These shifts will elevate cooling requirements for terminals, hangars, and other airport facilities, increasing operational costs and heat stress risks. Importantly, the study introduces a scalable methodology applicable to other climate-sensitive infrastructure and emphasizes the need for dual strategies: targeted adaptation measures such as energy-efficient technologies and passive cooling and global mitigation efforts to limit long-term temperature rise. This dual focus will strengthen the resilience of Nigerian airports and offers insights applicable to broader climate adaptation planning.

The thermal influence of Urban Heat Islands (UHIs) is not limited to periods of high temperature but persists throughout the year. The present study utilizes hourly data collected over a period of one year from a network of hygrothermal monitoring stations with a high density, which were deployed across the city of Cáceres (Spain). The network was designed in accordance with the World Meteorological Organization’s guidelines for urban measurements (employing radiation footprints and surface roughness) and ensures representation of each Local Climate Zone (LCZ), characterized by those factors (such as building typology and density, urban fabric, vegetation, and anthropogenic activity, among others) that influence potential solar radiation absorption. The magnitude of the heat island effect in this city has been determined to be approximately 7 °C in summer and winter at the first hours of the morning. In order to assess the energy impact of UHIs, Cooling and Heating Degree Days (CDD and HDD) were calculated for both summer and winter periods across the different LCZs. Following the implementation of rigorous quality control procedures and the utilization of gap-filling techniques, the analysis yielded discrepancies in energy demand of up to 10% between LCZs within the city. The significance of incorporating UHIs into the design of building envelopes and climate control systems is underscored by these findings, with the potential to enhance both energy efficiency and occupant thermal comfort. This methodology is particularly relevant for extrapolation to larger and denser urban environments, where the intensification of UHI effects exerts a direct impact on energy consumption and costs. The following essay will provide a comprehensive overview of the relevant literature on the subject.

ABSTRACT Cooling energy contributes significantly to residential energy demand in tropical regions. Specifically, the priming energy required for extracting the accumulated heat from the indoor environment to reach the desirable setpoint temperature, contributes to the peak demand. The priming energy accounts for up to 40% of the daily cooling energy in overheated and poorly ventilated spaces. Pre-cooling of buildings is a strategy that accelerates convective heat loss from the indoor environment, thereby reducing priming energy. This study establishes the priming energy demand reduction of air conditioners by adopting pre-cooling in a hot semi-arid (Köppen BSh) climate. Experimental studies were performed in a full-scale testbed where pre-cooling was enabled using a set of four speed-controllable ventilator fans. Validated energy simulations were conducted to optimize the ventilation rate and duration of fan operation for different time periods of the year. This helped establish optimal operational settings of the ventilator fans. Full-scale experiments confirmed that fan-forced pre-cooling contributed to a 40–75% reduction in the priming energy demand of the air conditioner based on the outdoor boundary conditions. The findings of the study can help in the development of control algorithms for pre-cooling systems in such residential settings.

Este estudio determinó el consumo eléctrico óptimo de sistemas de enfriamiento en cinco edificios ubicados en el Campus Hermosillo de la Universidad de Sonora, México, construidos bajo las directrices del organismo mexicano denominado Comité Administrador del Programa Federal de Construcciones Escolares (CAPFCE). Originalmente, estos edificios fueron diseñados para climas templados y construidos en todo el país, sin distinción de zonas climáticas. Se realizaron simulaciones en OpenStudio con termostatos a temperaturas de 17 °C, 24 °C y 28 °C, evaluándose cinco escenarios: cambios en la envolvente, ocupantes, iluminación, apertura de puertas/ventanas y estrategias combinadas. Las simulaciones se validaron in situ mediante cámara termográfica y sensores. Se obtuvieron valores anuales de carga térmica total y carga térmica sensible del sistema de enfriamiento, así como la temperatura operativa interior promedio. Los resultados muestran que en el mes de agosto, los consumos iniciales sin estrategias oscilaron entre 26.45 y 12.68 kWh/m², correspondiendo a la envolvente el 74–78 %, a los ocupantes el 20–25 % y menores porcentajes a la iluminación, ventilación e infiltración (<2 %). Con estrategias, los consumos finales bajaron a 22.36–11.42 kWh/m². El mayor ahorro provino de la eficiencia de los equipos (hasta 13.26 %), seguido por la implementación de aislamiento en muros (1.75 %), losas (0.71 %), ventanas de doble vidrio (0.03 %) y optimización de ventilación e iluminación (1.19 %). Elevar la temperatura del termostato de 17 °C a 28 °C redujo el consumo entre 25 % y 28 %, con mayor efecto cuando el consumo base era alto. Las cargas térmicas máximas fueron 59.79 y 51.84 kWh/m² (total y sensible) y las mínimas 0.31 y 0.0024 kWh/m², mientras que la temperatura interior sin enfriamiento varió de 34.06 °C a 20.8 °C. Los resultados confirman que la envolvente y la masa térmica determinan la demanda de enfriamiento, y que la eficiencia de los equipos y el ajuste del termostato son las estrategias más efectivas para reducir el consumo. No existen estudios previos que integren estas variables y resultados en edificios tipo CAPFCE, lo que aporta criterios aplicables a otras instituciones en climas cálidos secos.

Agro-industrial facilities host processes and products that are highly sensitive to thermal fluctuations. Given the projected increase in air temperatures in tropical regions due to climate change, improving indoor thermal conditions in these facilities has become critically important. Conventional cooling systems are widely used to maintain adequate indoor temperatures; however, they are associated with high energy consumption. In this context, Ground Source Heat Pump (GSHP) technology emerges as a promising alternative to reduce cooling loads by exchanging heat with the ground. This study evaluates the reductions in cooling energy consumption and the return on investment of a GSHP system integrated with conventional cooling system, considering a prototype agro-industrial room located in two ecotones of the Brazilian Midwest: the Amazon Forest (AF) and Brazilian Savanna (BS). Building energy simulations were performed using EnergyPlus software v. 9 under current climate conditions and climate change scenarios for 2050 and 2080. Initially, the prototype room was conditioned using a conventional HVAC system; subsequently, a GSHP system was integrated to enhance energy efficiency and reduce energy demand. Under current conditions, cooling energy demand in the BS and AF ecotones is projected to increase by 16.5% and 18.3% by 2050, and by 24.5% and 23.5% by 2080, respectively. The payback analysis indicates that the average return on investment improves under future climate scenarios, decreasing from 14.5 years under current conditions to 10.13 years in 2050 and 9.86 years in 2080. The findings contribute to understanding the thermal resilience and economic feasibility of ground-coupled heat exchangers as a sustainable strategy for mitigating climate change impacts in the agro-industrial sector.

This study selects typical existing office buildings in Zhengzhou, a region with a cold climate, as the research object and conducts a comparative analysis of the influencing factors of cooling energy consumption in west-facing and south-facing office spaces. A multi-stage sensitivity analysis methodology integrating global and local sensitivity methods is systematically applied to evaluate 13 key parameters across four categories: building morphology, envelope structure, shading measures, and active design strategies. Five parameters are consistently ranked among the top seven most sensitive parameters for both west- and south-facing orientations: the infiltration rate, the window-to-wall ratio, the cooling setpoint temperature, the number of shading boards, and building width. Two parameters exhibit orientation-specific differences, namely lighting power density and the external wall heat transfer coefficient in west-facing spaces, whereas shading board width and the external window heat transfer coefficient play a greater role in south-facing spaces. Local sensitivity analysis further reveals that within the parameter variation range, the five parameters with higher energy-saving rates for both orientations are air tightness, the window-to-wall ratio, the cooling setpoint temperature, the number of horizontal shading boards, and horizontal shading board width. By increasing the cooling setpoint temperature, south-facing spaces can achieve an energy-saving rate of 25.32%, which is significantly higher than the 21.77% achieved by west-facing spaces. Horizontal shading board width exhibits the most pronounced orientation difference, with south-facing spaces achieving an energy-saving rate of 16.69%, while west-facing spaces only reach 2.97%. The research findings offer quantitative scientific evidence for formulating targeted energy-saving retrofit strategies for existing office buildings in cold climate regions, thereby contributing to the meticulous development of building energy efficiency technologies.

Abstract In regions with hot climates and intense solar radiation, radiative cooling strategies can significantly reduce energy consumption to maintain indoor comfort. This study explores the impact of passive building cooling in urban canyons through radiative cooling techniques. The unique geometry of urban canyons, along with the radiative heat exchanges between the building surfaces that form these canyons, plays a crucial role in determining heat transfer through building envelopes. Taking into account the typical summer conditions in southern Spain, characterised by high solar radiation and high temperatures, this study evaluates the ability of a radiative cooling technique based on high-emissivity paints applied to building facades in urban canyons to reduce the heat flux towards the interior of the building. The methodology is based on the calculation of the heat flux through the envelope of three dwellings on each side of the urban canyon located at different heights. Two cases are analysed: a reference case that presents constructive characteristics typical of buildings constructed in Seville at the end of the last century and a retrofit case resulting from the application of a recently developed ultra-emissive cool paint to the outdoor surface of the walls of the reference buildings. From the comparative analysis of the heat fluxes computed, conclusions are drawn on the effectiveness of the use of the ultra-emissive cool paint in the context of urban canyons to reduce the thermal flux towards the interior of the dwellings and therefore reduce the energy consumption necessary to obtain indoor thermal comfort in the cooling season. The main contribution of the work is the elucidation of the ability of a recently developed ultra-emissive cold paint to reduce the energy flux through the façade of buildings that make up an urban canyon in the climatic context of summer in warm areas of southern Europe. As a result of the analysis performed, it is concluded that the use of the ultra-emissive cold paint considered for the retrofitting of the building envelopes under study can provide heat flux reductions through the envelopes in the range of 32.92% to 65% in the climatic and geographical context considered.

Traditional data-driven approaches emphasize input–output correlations and neglect dependencies among inputs, risking missed insights into key drivers of energy performance. Consequently, approaches that transcend correlation-centric analysis are warranted. Within this context, causal inference, which accounts for both statistical associations and temporal cause–effect relations, constitutes a promising direction. However, researchers cannot feasibly specify all causal relations relying solely on domain knowledge. Causal discovery is a data-driven methodology for analyzing causal relationships among variables, providing not only measures of association but also information on causal directionality. The authors employ two causal discovery algorithms—PC (Peter-Clark) and FCI (Fast Causal Inference)—on weather data. The discovered causal structures are compared, and two validation approaches are introduced to evaluate their statistical reliability; the authors also build on the identified causal structure to analyze the resulting causal pathways. The results show that both algorithms provide insights into causal relationships among variables, and the proposed validation approaches help establish the statistical reliability of the discovered structures. Moreover, the analysis of causal pathways indicates that causal effects can be identified and estimated with reliability.

As climate change accelerates, nearly zero-energy buildings (NZEBs) are emerging as a cornerstone of sustainable development. Rising global temperatures and shifting weather patterns necessitate innovative approaches to balancing heating and cooling demands while maximizing the integration of renewable energy sources. The study explores the future of NZEBs in the context of a warming climate, assessing the impact of global and regional climate change on building energy needs and adaptation strategies. It highlights cutting-edge technologies such as dynamic insulation, smart building envelopes, advanced energy management systems, and integrated HVAC solutions. Special emphasis is placed on modern passive cooling techniques, energy storage innovations, and the utilization of local renewable energy sources, including photovoltaics and geothermal systems. Additionally, the study examines the evolution of energy policies and building standards that facilitate NZEB development in the face of rising temperatures. Key challenges, including the increasing demand for cooling, the urban heat island effect, and the role of smart building management systems (BEMS) in optimizing energy performance, are critically analyzed Findings indicate that a holistic approach to the design and operation of NZEBs enhances energy efficiency while maintaining indoor comfort under changing climatic conditions.

Temperatures in the Mediterranean area have gradually risen in the last decades due to climate change, especially in the Italian Peninsula. This phenomenon has increased the cooling needs to ensure thermal comfort in buildings and, consequently, the use of refrigeration machines. Summer air conditioning is carried out mainly using compression machines powered by electricity supplied by the national network. All this contributes to the emission of climate-changing gases. To avoid this disadvantageous chain, compression machines could be replaced by absorption cooling systems powered by solar energy. The energy needs of the buildings in a time are directly proportional to the sum of positive differences between the outdoor air temperature and the indoor set point of the systems (equal to 26°C). The annual sum of hourly temperature differences defined above can be computed for each grid cell thanks to a numerical weather prediction model, namely the Weather Research and Forecasting model, that simulates the hourly temperatures on high-resolution computation grids and over fairly large extents. Maps of cooling consumption for buildings are thus produced. Choosing absorption solar energy-powered systems instead of vapor compression refrigeration systems leads to a drop in electrical energy consumption and therefore in emissions of greenhouse gases. In this work, different hypothetical scenarios of penetration of this technology have been considered. And the subsequent consumption of electricity withdrawn from the national grid has been estimated together with the reduction of greenhouse gas emissions.

Reflective materials, characterized by high albedo and thermal emissivity, offer effective passive cooling strategies for reducing building energy demand. While prior studies have developed thermal transfer models validated under laboratory conditions or conducted short-term monitoring in non-air-conditioned spaces, their effectiveness in operational buildings remains underexplored. This research evaluates the change in cooling energy demand and indoor thermal comfort in a retrofitted office building with reflective materials in China’s Hot Summer and Cold Winter (HSCW) zone. The calibrated WUFI®Plus simulations show that the application of reflective roof and window materials can result in an 11.3% reduction in cooling energy demand. Moreover, occupant surveys indicate improved thermal perception, with the mean Thermal Comfort Vote (TCV) rising from −0.75 to −0.30, thermal acceptability increasing from 0.10 to 0.35, and 80% of occupants reporting cooler conditions. These subjective results align with simulated Predicted Mean Vote (PMV) reductions (0.82 → 0.74), confirming the retrofit’s effectiveness. While the energy savings are more modest than those reported in Mediterranean climates, they are generally consistent with the energy saving ratios of buildings in the HSCW region as evaluated by previous studies. This study provides a framework for assessing retrofits in occupied buildings with reflective materials and indicates the practicality of such retrofits as an economic, low-disruption strategy for upgrading aging office building stocks in the HSCW zone.

Enhancing Marine HVAC Efficiency Through Free Cooling and Thermal Energy Storage: An Assessment in a Coastal City in India

Aligned with the sustainable development goals of affordable energy, health, and well-being, there is a growing focus on building energy efficiency and indoor environmental quality (IEQ). Solar radiation increases indoor mean radiant temperature, causing thermal discomfort for occupants near windows. To mitigate discomfort, it is inevitable to lower the indoor temperature, which may lead to increased electricity consumption. We set up test units with glass types having SHGC from 0.28 to 0.85 and also installed sensors near windows to measure the impacts of solar radiation on PMV and cooling consumption. Environmental Quality Index (EQI) serves as an indicator for assessing thermal conditions. EQI categorizes time fractions into seven levels (A to G), based on PMV categories of the thermal environment. At a set-point of 26°C, the test unit equipped with the lowest SHGC records an average daily electricity consumption of 1.23 kWh/day, with an EQI of C. In comparison, the test unit with the highest SHGC consumes 2.96 kWh/day, reflecting an EQI of G. Lower SHGC glass effectively blocks incident sunlight, resulting in reduced electricity consumption and improved indoor thermal comfort. To address discomfort stemming from high SHGC values, the set point was lowered to 24°C. Consequently, the test unit with the highest SHGC experienced an increase in EQI to E, accompanied by higher electricity consumption of 3.57 kWh/day. This study emphasizes the importance of using EQI as a unified benchmark for comparing the energy-saving potential of glasses, as temperature-based assessments may underestimate the potential of low SHGC glass.

Commute duration and electric vehicle ownership influence hourly residential cooling demand through their effects on household occupancy patterns. Using data from 10,000 U.S. households, travel behavior was linked to building energy simulation through a co-simulation framework focused on Tucson, AZ, USA. Long commutes were associated with higher peak-to-valley load ratios, while electric vehicle households showed flatter demand profiles with increased early morning and evening loads.

Optimizing Green Roof Design to Reduce Cooling Energy Demand in a Jordanian Hospital Building

In Saudi Arabia’s hot and arid climate, residential buildings account for over half of national electricity consumption, with cooling demands alone responsible for more than 70% of this use. This paper explores the hypothesis that contemporary villa designs are inherently inefficient and that current building regulations fall short of enabling adequate thermal performance. This issue is expected to become increasingly significant in the near future as external temperatures continue to rise. The study aims to assess whether passive design strategies rooted in both engineering and architectural principles can offer substantial reductions in cooling energy demand under current and future climatic conditions. A typical detached villa was simulated using IES-VE to test a range of passive measures, including optimized window-to-wall ratios, enhanced glazing configurations, varied envelope constructions, solar shading devices, and wind-tower-based natural ventilation. Parametric simulations were conducted under current climate data and extended to future weather scenarios. Unlike many prior studies, this work integrates these strategies holistically and evaluates their combined impact, rather than in isolation while assessing the impact of future weather in the region. The findings revealed that individual measures such as insulated ceilings and reduced window-to-wall ratios significantly lowered cooling loads. When applied in combination, these strategies achieved a 68% reduction in cooling energy use compared to the base-case villa. While full passive performance year-round remains unfeasible in such extreme conditions, the study demonstrates a clear pathway toward energy-efficient housing in the Gulf region.

Adaptive façades, also known as climate-adaptive building shells (CABSs), could make a significant contribution towards reducing the energy consumption of buildings and their environmental impacts. There is extensive research on glazed adaptive façades, mainly due to the available technology for glass materials. The technological development of opaque adaptive façades has focused on variable-thermal-resistance envelopes, and the simulation of this type of façade is a challenging task that has not been thoroughly studied. The aim of this study was to configure and validate a simplified office model that could be used for simulating an adaptive façade with variable thermal resistance via adaptive insulation thickness in its opaque part. Software-to-software model comparison based on the results of an EnergyPlus Building Energy Simulation Test 900 (BesTest 900)-validated model was used. Cooling and heating annual energy demand (kWh), peak cooling and heating (kW), and maximum, minimum, and average annual hourly zone temperature variables were compared for both the Adaptive and non-adaptive validated model. An Adaptive EnergyPlus model based on the BesTest 900 model, which uses the EnergyPlus SurfaceControl:MovableInsulation class list, was successfully validated and could be used for studying office buildings with a variable-thermal-resistance adaptive façade wall configuration, equivalent to a heavyweight mass wall construction with an External Insulation Finishing System (EIFS). An example of the Adaptive model in the Denver location is included in this paper. Annual savings of up to 26% in total energy demand (heating + cooling) was achieved and could reach up to 54% when electro-chromic (EC) glass commanded by a rule-based algorithm was added to the glazed part of the variable-thermal-resistance adaptive façade.

Abstract Climate change significantly influences electricity and energy demand, yet a comprehensive understanding of heating and cooling energy demand in China’s major cities under the impact of global warming remains incomplete. This study utilized monthly electricity consumption and mean air temperature data to accurately determine the base temperatures for Beijing and Shanghai, identified as 18.94° and 19.54°C, respectively. We further established the heating degree-day (HDD) and cooling degree-day (CDD) indices for both cities over the period from 1961 to 2020. The results indicate a declining trend in winter heating demand and an increasing trend in summer cooling energy demand in both Beijing and Shanghai from 1961 to 2020. Notably, the decrease in winter heating demand exceeds the increase in summer cooling demand for each city. The findings indicate a higher sensitivity of electricity demand to temperature in Beijing during summer (+3.5519 TWh °C−1) compared to winter (−1.5706 TWh °C−1). Similarly, in Shanghai, temperature sensitivity is higher in summer (+5.1133 TWh °C−1) than in winter (−1.7133 TWh °C−1). This high sensitivity during the summer months implies an overall increase in future energy demand. While Beijing demonstrates a higher demand for winter heating compared to Shanghai, its demand for summer cooling is comparatively lower. Nevertheless, due to Shanghai’s greater sensitivity of electricity demand to temperature compared to Beijing, it is projected that Shanghai’s total energy demand will exceed that of Beijing in the future. Significance Statement Climate change alters the demand for electricity and energy, and a comprehensive understanding of heating and cooling energy demand in China’s megacities under global warming is yet to be attained. By calculating the heating and cooling degree-day indices in Beijing and Shanghai, but using real base temperatures, these indices provide a comprehensive resource for exploring the changes in heating and cooling energy demand in Beijing and Shanghai against the background of global warming. Our study shows a decreasing trend in winter heating demand and an increasing trend in summer cooling energy demand for Beijing and Shanghai from 1961 to 2020, and the total energy demand in Beijing and Shanghai will still increase in the future.