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Even though global warming is expected to raise the energy demand in office buildings, most energy analyses and design studies neither consider its impacts nor adaptive energy solutions. This study evaluates the effects of future climate on the energy demand of an office building in Portugal and proposes mitigation measures to improve its energy performance and environmental sustainability. The study simulates the energy demand of the building in 2055 and 2090 under different future scenarios using data from the latest climate model experiments, considering systems, envelopes, and operations interventions, and assesses the potential of photovoltaic panels to meet the energy demand. The results show that the interventions may reduce electric energy consumption between 16 % and 25 %, and the photovoltaic panels can meet 23 %–59 % of the total demand, depending on the scenario and the year. However, storage technology and equipment efficiency must evolve favorably to reach low energy. The findings reveal if a building designed and optimized for the current climate will remain optimal in the future and demonstrate the benefits of applying cleaner production and sustainable consumption principles to the office building sector. The study provides valuable insights for practitioners and policymakers. [Display omitted] • The impact of future scenarios on an office building's energy demand is assessed. • Alternative measures are analyzed to improve energy performance in 2055 and 2090. • The electric demand may be reduced by up to 16 %–25 % in the future. • The impact of the climate scenario may be significant. • PV panels may reduce the purchased electric energy by around 23–59 % in the future. [ABSTRACT FROM AUTHOR]

Highlights • The U-value impact on the thermal performance of residential buildings was analyzed. • 192000 buildings were randomly generated and evaluated using dynamic simulation. • Six geometry-based indexes were correlated with the buildings performance. • Higher U-values can decrease energy consumption in lower latitudes. • Higher and wider U-value intervals increase the geometric freedom for lower latitudes. Abstract Contrarily to what happens in northern European countries, buildings in the Mediterranean region are prone to overheating. Consequently, it is important to better understand the role that the thermal transmittance of the building envelope elements has on air-conditioning consumptions. This paper analyzes the effect of different U -values on building design in the Mediterranean area. 192 000 residential buildings were randomly generated for sixteen distinct locations and the energy consumption was assessed for each. It was found that in northern Mediterranean locations, as U -values decreased, energy consumption also decreased. However, in warmer climates, low thermal transmittances tended to significantly increase energy consumption. Hence, the lower the latitude, the higher the U -values should be, in order to prevent increasing the cooling demands. Additionally, geometry-based indexes were correlated with the building's energy performance. For high U -values, it was found that bigger buildings worsen the energy performance and larger windows tended to improve it. For low U -values, bigger north-facing windows were beneficial. There is an adequate interval of values for which the geometry has a lower impact, which is wider and higher for lower latitudes, thus meaning that not only does the building performance improve but architects are also freer to explore alternative designs. [ABSTRACT FROM AUTHOR]

Highlights • The U -value impact on the thermal performance of residential buildings was analyzed. • 96,000 buildings were randomly generated and evaluated using dynamic simulation. • Six geometry-based indexes were correlated with the buildings performance. • Low U -values can increase energy consumption in warm and moderate climates. • Adequate U -values allow designers to explore new building forms and window designs. Abstract European countries impose regulations for low thermal transmittance envelopes to improve the buildings' energy efficiency. However, in scientific literature, evidences are surfacing that such low U -values are affecting the validity of traditional design guidelines. The purpose of this paper is to analyze the implications of lowering the envelope U -values. To achieve this, 96,000 residential buildings were generated, with random geometries and U -values, and their energy consumption evaluated for eight European locations. The buildings were grouped according to the envelope elements' thermal transmittance and the results statistically analyzed. For each group, six geometry-based indexes were correlated with the energy performance. As U -values decrease, the performance variation amplitude was found to reduce, making the geometry less important. However, in warm/moderate climates, low U -values tend to actually increase the energy consumption and also rise the performance variation, meaning that geometry regains importance. In this case, instead of helping reducing the heating demands, solar exposed windows and compact geometries raise the energy consumption. It is concluded that, for each climate location, there is an ideal U -value range for which the energy demand is low and the geometry effect becomes less significant, thus freeing designers to further explore building forms and window designs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Heat convection models have several limitations in dynamic simulation. • Different models produce significantly different energy performances. • Wind direction is not adequately considered in EnergyPlus. • The models show spikes and steps in a building's 360° orientation curve. • New convection models are needed to improve precision and reliability. Wind plays an essential role in the heat convection on building outside surfaces. In EnergyPlus, a dynamic simulation program, heat convection models present several limitations reported by the scientific community. However, this communication reveals and discusses some implications that highlight the importance of developing more accurate models. The current models are first analyzed to identify what are the pitfalls considering the influence of wind direction on the thermal performance of the building walls. Then, a discussion is made on why their implications are important and, lastly, it is suggested how wind direction-driven studies and new models can overcome this issue. Concluding, this communication calls for efforts from the scientific community to research and develop more accurate models for wind-driven surface convection. [ABSTRACT FROM AUTHOR]

• Ideal U -values for 2050 climate projection in the Mediterranean region are determined. • Current well insulated buildings are not prone to overheating in the future. • In the future, ideal U -values are similar or even lower than current ones. • Casablanca is the only location presenting an overheating risk. • The increase of cooling demand will overcome the heating demand decrease. One of the effects of climate change is global warming, which will increase cooling demand in buildings. However, scientific literature does not show consensus on the risk of highly insulated buildings being prone to overheating. This paper presents a statistical comparison of two synthetic datasets for current and future climates in sixteen Mediterranean locations. The weather data for the 2050 climate projection was generated by 'morphing' current weather data. The buildings were created using a generative design method to produce random geometries and random U -values for the envelope elements. Energy performance was evaluated using dynamic simulation. In addition to the expected general increase in cooling demand (up to 137 %) and a smaller reduction in heating demand (up to 63 %), the results demonstrate that the ideal U -values used in the current climate in almost all of the locations will not cause overheating. In several cases, the decrease of the U -values is even recommended for Podgorica, Valencia, Tunis, Malaga, Larnaca, and Alexandria, as the reduction of heating demand compensates the increase of cooling demand. Casablanca was the only location showing an increase in the ideal U -values, thus presenting risk of overheating if using current ideal U -values. [ABSTRACT FROM AUTHOR]

Efficient ventilation is an effective method for reducing thermal loads inside buildings, thus decreasing cooling energy consumption. This is especially relevant in warmer climates. Therefore, it is important to better understand the role that different ventilation parameters play on air-conditioning consumptions. This study analyzes the effect of three different ventilation parameters – air flow rate, minimum indoor temperature and indoor-outdoor temperature difference – on the energy performance of buildings in the Mediterranean region. A set of 500 residential building geometries was randomly generated and the energy consumption for different combinations of ventilation parameters was assessed in sixteen distinct locations. Results suggested that the ventilation specifications that minimize air-conditioning energy consumption fall within similar values for all the evaluated locations: ventilation rates of at least 10 air changes per hour, a minimum indoor temperature for ventilation slightly below the building's cooling setpoint, and a low indoor-to-outdoor temperature difference. It was also found that, in lower latitudes, the buildings' energy performance tended to become similar, thus reducing the impact of their geometry and orientation. These results may help building practitioners to infer the most adequate ventilation strategies to implement, since this study is not limited to specific ventilation methods. • The ventilation impact on energy performance of residential buildings was analyzed. • 500 buildings were randomly generated and evaluated using dynamic simulation. • Similar ventilation specifications can be used for all the evaluated locations. • Ventilation rates of at least 10 ACH show to be the most adequate. • In lower latitudes, geometry and orientation are less impacting on energy performance. [ABSTRACT FROM AUTHOR]

• Datasets of low and high thermal mass with random U -values are compared. • Low thermal mass buildings have lower and wider range of ideal U -values. • High thermal mass buildings demand more cooling energy. • Buildings with high thermal mass consume lesser heating energy in warmer climates. • Thermal mass impacts differently the energy consumption along the U -value scale. High thermal mass construction is commonly used to reduce cooling energy consumption during the summer period as a passive design strategy in the Mediterranean region. Although being a generalized design practice, the benefit to the building performance is not fully consensual within the scientific community. This work explores the influence of thermal transmittance on the energy efficiency of buildings with different thermal mass levels. Hence, a statistical comparison of the buildings' annual energy consumption for air-conditioning is carried out based on two synthetic datasets with high and low thermal mass and varying thermal transmittance for opaque and transparent elements. In addition to climate location, the results demonstrate that thermal transmittance has varying impact on the contribution of thermal mass. The locations presenting such behavior were Marseille (−0.99% to +3.89%), Istanbul (−0.73% to +4.21%), Valencia (−1.31% to +4.97%), Algiers (−2.32% to +3.81%), Malaga (−3.95% to +6.21%), Casablanca (−5.66% to +6.96%), and Tel Aviv (−1.81% to +5.44%). These findings demonstrate that the influence of thermal mass is more complex than previously thought and levels should be chosen in relation with the thermal transmittance value. [ABSTRACT FROM AUTHOR]

This paper critically reviews the role of performance-based generative design in fast prototyping of buildings, describes the methodology of an automated generative layout design to produce complete building solutions, and presents a case study of multi-story buildings in urban context. The proposed approach evolves the building design solutions by interacting with the city 3D geometry and evaluates the energy consumption for air-conditioning. The building designs take into consideration urban geometric constraints and objectives, such as alignment with surrounding buildings, urban lot area, and relative and absolute position of the generated elements. During the evaluation process, the urban context is considered for casting shadows and reflecting solar radiation. The case study consists of six alternative 15-story buildings located in the city of São Paulo (Brazil), having commercial areas on the ground floor and two apartments per story on the remaining floors. The results show that, despite having similar apartments in every story, the urban context has a relevant impact on the buildings' energy performance. The difference between the apartments' best and worst energy performing stories ranges from 9% to 12% (ignoring the outlier story located in the first level), depending on the building solution. The results also show that the most energy efficient apartments' story is not located in the top or bottom floors, but rather at an intermediate level. • Urban context is added to an automatic floor plan generation procedure. • Alternative 15-story buildings are generated with residential and commercial spaces. • Energy consumption for air-conditioning is evaluated for every apartment. • Shadows and reflections from surroundings are evaluated during dynamic simulation. • Stories' energy performance vary from 9% to 12% despite having similar geometry. [ABSTRACT FROM AUTHOR]

The climate will become hotter, and buildings will perform differently as outdoor conditions evolve. If the lowest energy demand is desired, it is crucial to determine the ideal thermophysical properties of the envelope over the buildings' life span. However, the scientific literature is still scarce in providing a compelling answer. Therefore, this study (i) determines ideal thermal transmittance values (U -values) for present-day and future climates, (ii) determines to what extent the thermophysical properties will need to change to remain ideal, (iii) identifies different trends of U -values over time, (iv) establishes a relationship between outdoor air temperatures, cooling and heating setpoints, and ideal U -values, and (v) proposes a set of design strategies according to each trend. The EPSAP generative design method was used to create a large dataset of residential buildings with random geometries and U -values to evaluate their energy demand for heating and cooling in EnergyPlus. The thermal performance of each building was evaluated for 30 locations in Brazil for the current period and two future timeframes (2050 and 2080). The Future Weather Generator tool was used to morph today's typical meteorological weather to match the EC-Earth3 data for the SSP5–8.5 scenario. Although climate change has a similar relative impact, its consequences differ over time in each location. The ideal U -values have different trends in different regions: (a) remaining unchanged in the future, (b) changing from being the highest possible to the lowest of the analyzed range in 2050 or 2080, and (c) being mid-range values in the present and with similar or lower values in the future climate. The impact on the thermal loads of maintaining the present-day ideal U -values also varies significantly in the future timeframes, from being nil to representing an increase reaching 30 % in 2050 (∆ 2.94 MW·h ± 0.06 MW·h) and 57 % in 2080 (∆ 6.05 MW·h ± 0.09 MW·h). Therefore, building design professionals need to use different strategies according to each region and consider how climate evolves during the lifetime of the building. • Ideal U -values in present-day and future climates in Brazil are determined. • The trend of the ideal U -values varies according to each region. • A relation between U -values and outdoor temperatures and HVAC setpoints was found. • A fast procedure is presented to determine the trend of the ideal U -values over time. • For each trend, building design strategies are proposed. [ABSTRACT FROM AUTHOR]

Strong convergence problems may arise during the dynamic simulation of the phase transitions of adsorption systems subjected to larger and/or random fluctuations of the boundary conditions, which do not follow the conventional cycle sequence (e.g., adsorptive thermal storage systems). This sequence could even be reversed at some instants and its stages not completed. Such convergence problems preclude solving those phase transitions, and thus the successful dynamic simulation of the adsorption systems. A set of numerical procedures for solving those problems is proposed, consisting of a small group of new conditions to be added to the conventional numerical algorithms. Its successful use is demonstrated in the dynamic simulation of a thermal energy storage system provided with an adsorption module, modeled in two distinct but coupled platforms (TRNSYS and MATLAB), for which the convergence difficulties are identified and described. Results indicate successful convergence by applying the proposed methodology, in contrast with the original algorithm, attesting for its capability to overcome the convergence problems that occur during the system's dynamic simulation. This set of numerical recipes can be adapted for other systems' algorithms, or to serve as a basis for its successful dynamic simulation, thus showing a promising and enlarged range of use. [ABSTRACT FROM AUTHOR]