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Air Conditioning (AC) appliances are a highly effective adaptation strategy to rising temperatures, thus making future climate conditions an important driver of space cooling energy demand. The main goal of this study is to assess the impacts of climate change on Cooling Degree Days computed with wet-bulb temperature (CDDwb) and household space cooling demand in Brazil. We compare the needs under three specific warming levels (SWLs) scenarios (1.5 °C, 2 °C and 4 °C) to a baseline with historically observed meteorological parameters by combining CDDwb projections with an end-use model to evaluate the energy requirements of air conditioning. The effects of the climate change were isolated, and no future expansion in AC ownership considered. Carbon dioxide (CO2) emissions associated with AC energy demand are also calculated. Results show an increase in both average CDDwb and AC electricity consumption for the global warming scenarios in all Brazilian regions. The Northern region shows the highest increase in CDDwb (187% in CDDwb for SWL 4 °C), while the Southeast presents the highest AC energy consumption response (326% in the AC energy consumption for SWL 4 °C) compared to the baseline. At the national level, CDDwb and the AC energy consumption in all SWLs scenarios grow by 70%, 99% and 190%, respectively.

This study investigates Europe's space cooling energy field. The work aims to assess the European Union (plus the United Kingdom) final energy consumption for space cooling in both the residential and service sectors with 2016 as a baseline. An extensive literature review of datasets and journal papers has been conducted to fill the knowledge gaps of the investigated energy branch. The European space cooling market is mainly dominated by vapour compression (VC) technologies which, in this study, have been grouped as room air conditioners (RACs) and centralized air conditioners (CACs). These technology groups have been investigated, and their installed capacities, energy efficiency levels (seasonal energy efficiency ratio—SEER), equivalent full load hours (EFLHs), and amount of space cooling units installed have been identified as essential parameters to calculate the final energy consumption for space cooling. Overall, the total value of the European final energy consumption for the space cooling sector, including both the residential and service sectors, results in 106 TWh/year.

Analyzing the Köppen–Geiger climate classification and available climate data for the southern European Mediterranean coast, eight reference geolocations were selected for this analysis: the cities of Valencia, Barcelona, Marseille, Rome, Koper, Split, Athens and Nicosia. The first part of the research applies the climate potential for natural ventilation (CPNV) methodology that evaluates the theoretical availability of natural ventilation (NV) for each city location corresponding to human hygrothermal conditions. The second part of the article evaluates possible cooling energy savings (ES) applying the advanced natural ventilation (ANV) space-cooling strategy. A hypothetical four-story atrium office building model is designed for the building performance simulation (BPS) using mixed-mode (or hybrid-mode) and night-time natural ventilation (NNV) approaches. The objective is to present a comparison overview of possible space cooling ES between chosen geolocations. In the context of the current European Union's (EU) energy transition (ET) process, the article displays ANV possibilities, as a renewable energy source (RES), in the reduction of building space cooling energy demands (ED) on the electricity grid. ; Peer Reviewed ; Postprint (published version)

Analyzing the Köppen–Geiger climate classification and available climate data for the southern European Mediterranean coast, eight reference geolocations were selected for this analysis: the cities of Valencia, Barcelona, Marseille, Rome, Koper, Split, Athens and Nicosia. The first part of the research applies the climate potential for natural ventilation (CPNV) methodology that evaluates the theoretical availability of natural ventilation (NV) for each city location corresponding to human hygrothermal conditions. The second part of the article evaluates possible cooling energy savings (ES) applying the advanced natural ventilation (ANV) space-cooling strategy. A hypothetical four-story atrium office building model is designed for the building performance simulation (BPS) using mixed-mode (or hybrid-mode) and night-time natural ventilation (NNV) approaches. The objective is to present a comparison overview of possible space cooling ES between chosen geolocations. In the context of the current European Union's (EU) energy transition (ET) process, the article displays ANV possibilities, as a renewable energy source (RES), in the reduction of building space cooling energy demands (ED) on the electricity grid. ; Peer Reviewed ; Postprint (published version)

The energy needs for space cooling are becoming a significant share of the energy balance of different Member States of the European Union, in particular the Mediterranean countries. This trend has been observed and monitored by the European Union, which has started a number of initiatives to promote the reduction in the energy demand for space cooling and have it satisfied by renewable energy sources, such as photovoltaic electrical energy. Nevertheless, even if the potential of those solutions has been widely investigated at the single-building level, this scale of analysis seems not fully adequate to support the definition of the energy policies addressed towards the renovation of the current cities into smart ones, with a large share of their energy demand satisfied with renewable energy. In this framework, this research aims to investigate the topic of building energy performance for space cooling services by adopting an urban-scale approach. In detail, a parametric simulation plan was run with CitySim in order to assess the impact of different quantities, i.e., climate conditions, districts' and buildings' geometry features, and the thermal quality of the building envelope, on the overall cooling energy need for districts and the specific building energy performance. Furthermore, the advantages of the integration of photovoltaic systems to supply power to the cooling system were analyzed, identifying the district configurations with the highest potential. For instance, in Athens, the share of space cooling demand satisfied by PV in high-rise nZEB configurations ranges between 64% (Building Density = 0.25) and 87% (Building Density = 1), while in the low-rise nZEB configurations it ranges between 81% (Building Density = 0.25) and 75% (Building Density = 1).

With the rapid process of urbanization and global warming, many metropolises are vulnerable to high temperatures in summer, threatening the health of residents. However, green spaces can generate a cooling effect to mitigate the urban heat island effect in big cities. They can also help to improve the living quality and wellbeing of surrounding residents. In this paper, we utilized the radiative transfer equation algorithm, k-means clustering algorithm, big data crawling, and spatial analysis to quantify and map the spatial distribution, cooling capacity, and cooling contribution for surrounding communities of 1,157 green spaces within Beijing Fifth Ring Road, a typical metropolitan area. The findings showed that (1) the area proportion of the heat island in the study area is larger than that of the cooling island. Accounting for only about 30% area in the study area, the green spaces reduce the average land surface temperature by 1.32°C. (2) The spatial features of green space, such as area and shape complexity, have a significant influence on its cooling effect. (3) Four clusters of green spaces with specific spatial features and cooling capacity were identified. And there were differences among these clusters in green space cooling contribution for the surrounding communities. (4) The differences in green space cooling contribution also existed in different urban zones. Specifically, the middle zone performed significantly better than the inner and outer zones. (5) We furthered in finding that some green spaces with medium and high cooling contributions need to improve their cooling capacity soon, and some green spaces with low cooling contributions or no contributions have a good potential for constructing new communities in the future. Our study could help planners and government understand the current cooling condition of green spaces, to improve their cooling capacity, mitigate the urban heat island effect, and create a comfortable and healthy thermal environment in summer.

The paper systematically reviews and compares 88 scenarios of energy demand in commercial and residential buildings that include the additional energy use or savings induced by thermal adaptation in heating and cooling needs at global level. The resulting studies are grouped in a novel classification that makes it possible to systematically understand why the energy projections of integrated assessment models vary depending on how changes in climatic conditions and the associated adaptation needs are modeled. Projections underestimate the energy demand of the building sector when it is driven only by income, population, unchanging climatic conditions and their associated adaptation needs. Across the studies reviewed, already by 2050 climate change will induce a median 30% (90%) percentage variation of a building's energy demand for cooling and a median -8% (-24%) percentage variation for heating, leading to a 2% (13%) increase when cooling and heating are combined, under the Representative Concentration Pathway 1.9 (8.5). The results underscore that models lacking extensive margin adjustments, and models that focus on residential demand, highly underestimate the additional cooling needs of the building sector. Topics that deserve further investigation regard improving the characterization of adopting energy-using goods that provide thermal adaptation services and better articulating the heterogeneous needs across sectors.

Urban green infrastructure (UGI) and nature-based solutions (NBS) are increasingly recognized as strategies to address urban sustainability challenges. These solutions are attracting key scientific and marketing attention thanks to their capability to improve indoor and outdoor thermal comfort and environmental quality of spaces. In urban areas, where most of the population worldwide lives, indoor-outdoor environmental quality is compromised by local and temporary overheating phenomena, air pollution concentration, and impervious surfaces minimizing urban space resilience to climate change related hazards. In this view, the proposed study concerns the analysis of a greenery system for enhancing outdoor thermal conditions and local warming mitigation for pedestrians for the continental Mediterranean climate. The system has the purpose of designing an outdoor 'alive' shading system to be applied in open public spaces, with producing physical and societal benefits. The experimental results showed that the implementation of the greenery, characterized by lower surface temperatures and evapotranspiration compared to a simple pergola system, allows the reduction of outdoor air temperature under the shading system and, thus, higher relative humidity in summer. Specifically, the hygrothermal cooling and the additional shading thanks to the presence of greenery provide local air temperature reduction up to 5 C at pedestrian level. ; Funding: This work was partially funded by the Ministerio de Ciencia, Innovación y Universidades de España (RTI2018-093849-B-C31 - MCIU/AEI/FEDER, UE). This work was partially funded by the Ministerio de Ciencia, Innovación y Universidades - Agencia Estatal de Investigación (AEI) (RED2018-102431-T). The authors from University of Perugia thank Fondazione Cassa di Risparmio di Perugia for supporting the investigation about biomaterials within the project SOS CITTÁ 2018.0499.026. Acknowledgments: The authors would like to thank the Catalan Government for the quality accreditation given to their research group (2017 SGR 1537). GREiA is a certified agent TECNIO in the category of technology developers from the Government of Catalonia. This work is partially supported by ICREA under the ICREA Academia programme.

The energy consumption globally has been increasing drastically the past decades, mainly due to the population growth and the industrial and technological progress. In order to address this issue, the European Union has launched several directives to decrease energy use, increase energy efficiency and increase use of renewable energy sources. The aim is that by 2020 all new buildings should be nearly zero-energy buildings. A solution that could contribute to this is the combination of photovoltaic panels for the production of electricity and phase change material (PCM) for the reduction of peak cooling demand. In the present simulation study, the coupling of nighttime radiative cooling with PCM for cooling an office room was investigated. For cooling water through nighttime radiative cooling two types of solar panels were utilized, an unglazed solar collector and photovoltaic/thermal (PV/T) panels. Apart from cold water for space cooling, the installation was capable of providing domestic hot water from both types of panels and electricity from the PV/Ts. This system was simulated for the period from 1st of May until 30th of September, under the weather conditions of Copenhagen (Denmark), Milan (Italy) and Athens (Greece). In Athens and Milan the operative temperature was within the range of Category III of EN 15251 (23 – 26oC, 73.4 – 78.8oF) for 81% and 83% of the occupancy period respectively, while in Copenhagen it was within the range only for 63%. Furthermore, the percentage of PCM used at the end of the occupancy period was 86%, 81% and 80% for Copenhagen, Milan and Athens, respectively. Nighttime radiative cooling provided for Copenhagen 61%, for Milan 36% and for Athens 14% of the cooling energy required for discharging the PCM. Furthermore, the average cooling power per unit area provided by the PV/T panels was 43 W/m2 for Copenhagen, while for Milan and Athens it was 36 W/m2 and 34 W/m2, respectively. The cooling power of the unglazed solar collector was negligible. Finally, the total electricity produced in Copenhagen for the simulated period was 371 kWh, while for Milan and Athens it was 380 and 439 kWh, respectively. It was concluded that the nighttime radiative cooling can be a satisfying solution for providing space cooling to office buildings. The performance of the installation could be improved by implementing a solar shading system and a more precise control strategy.

Climate change is becoming more important day after day. The main actor to decarbonize the economy is the building stock, especially in the energy used for Domestic Hot Water (DHW), heating and cooling. The use of renewable energy sources to cover space conditioning and DHW demands is growing every year. While solar thermal energy can cover building heating and DHW demands, there is no technology with such potential and development for space cooling. In this paper, a new concept of combining radiative cooling and solar thermal collection, the Radiative Collector and Emitter (RCE), through the idea of an adaptive cover, which uses different material properties for each functionality, is for the first time experimentally tested and proved. The RCE relies on an adaptive cover that uses different material properties for each functionality: high spectral transmittance in the solar radiation band and very low spectral transmittance in the infrared band during solar collection mode, and high spectral transmittance in the atmospheric window wavelength during radiative cooling mode. Experiments were performed during the summer period in Lleida (Dry Mediterranean Continental climate). The concept was proved, demonstrating the potential of the RCE to heat up water during daylight hours and to cool down water during the night. Daily/nightly average efficiencies up to 49% and 32% were achieved for solar collection and radiative cooling, respectively. ; This research was funded by the Oficina de Desenvolupament i Cooperació (ODEC), the Catalan Government (AGAUR–Generalitat de Catalunya) under grant agreement 2017 SGR 659, the Spanish government (Ministerio de Ciencia, Innovación y Universidades) under grant agreement RTI2018-097669-A-I00.

Space cooling demand is increasing globally due to climate change. Cooling has also been linked to all 17 sustainable development goals of the United Nations. Adequate cooling improves productivity and thermal comfort and can also prevent health risks. Meanwhile, policy initiatives such as the European Union's Green Deal require participants to cut greenhouse gas emissions and reduce energy use. Therefore, novel cooling systems that are capable of efficiently producing high levels of thermal comfort are needed. Radiant cooling systems provide a design capable of fulfilling these goals, but their application in hot and humid climates is limited due to the risk of condensation. In this study, we compare the performances of radiant cooling systems with and without dehumidification. The studied systems are supplied by geothermal energy. The study is conducted using building energy models of a small office building belonging to a three-building school complex located in Sant Cugat near Barcelona in Spain. The studied location has a Mediterranean climate. The simulations are conducted using IDA Indoor Climate and Energy 4.8 simulation software. The results show that the radiant cooling system with dehumidification (RCD) produces considerably improved thermal comfort conditions, with maximum predicted mean vote (PMV) reached during the cooling season being 0.4 (neutral) and the maximum PMV reached by the radiant cooling system without dehumidification (RC) being 1.2 (slightly warm). However, the improved thermal comfort comes at the cost of reduced energy and exergy efficiency. The RCD system uses 2.2 times as much energy and 5.3 times as much exergy as the RC system. A sensitivity analysis is also conducted to assess the influence of selected input parameters on the simulation output. The results suggest that maximising dehumidification temperature and minimising ventilation flow rate can improve the energy and exergy efficiency of the RCD system while having a minor effect on thermal comfort.

The total energy consumption in a house in Chile includes 30% of heating expenses, increasing to 60% in the winter period. The current energy source are fossil fuels, which can be replaced by the sun, with an efficient implementation of the use of PCM for passive cooling/heating space from solar radiation, benefiting the environment. In the north of Chile there is a solar radiation index of approximately 2750 kWh·m-2, low cloudiness and low precipitation rates, indicating an important source of energy and great opportunity for improvement in the use and management of energy resources. Moreover, mining camps present in large numbers in the northern zone require a lot of energy to cool and heat the space. This research shows the thermal behavior in summer and winter of two lightweight constructions, similar to the type used in mining camps, with dimensions of 2.5 x 2.5 x 2.5 m at pilot scale installed at the University of Antofagasta, Chile. One of these modules contains PCM on the inside of the walls and ceiling, while the other does not, to analyze the effect of PCM by comparison. The results of this work show that in winter (August) the application of PCM favors the permanence within the thermal comfort zone, with a difference of 5°C. In summer there is an opposite effect (January), experiencing a higher temperature increase inside the container with PCM, with a difference of 4°C. According to the constructive characteristics, properties and quantity of PCM used, and the effect of solar radiation on the structure and environmental conditions, there are benefits in energy saving and efficiency in the winter period, while summer shows results that enhance the study and analysis of the applied technology to solve the thermal behavior shown in this season. ; The authors acknowledge the financial support of CONICYT/FONDAP N° 15110019, CONICYT/PCI/REDES N° 170131 and CONICYT/FONDECYT/REGULAR/N° 1170675.This work was partially funded by the Ministerio de Ciencia, Innovación y Universidades de España (RTI2018-093849-B-C31 -MCIU/AEI/FEDER, UE). The authors would like to thank the Catalan Government for the quality accreditation given to their research group (2017 SGR 1537). GREiA is a certified TECNIO agent in the category of technology developers from the Government of Catalonia. This work is partially supported by ICREA under the ICREA Academia programme.