Adaptive comfort criteria in transitional spaces: a proposal for outdoor comfort

Urban Heat Island (UHI) as a combined consequence of global warming and the cities diameter increase, continues to be technological challenges today. Different passive strategies related to the buildings and cities architecture design imply energy demand reduction achieving. Architectural elements such as courtyards become extraordinarily significant as passive cooling systems. The research aims to establish patterns and values of adaptive comfort in transition spaces, reflected in the thermal regulation capacity of these buildings thanks to the morphology of the courtyards, contributing also to possible state strategies for action in favor of reducing the effects of climate change

Comparative evaluation of passive conditioning strategies for the improvement of courtyard thermal performance

[EN] The alarming increase in global average temperatures and the adaptive capacity of humans in relation to air quality and temperature are becoming increasingly relevant. Scientific resources have focused on the thermal adaptation of building users, but little research has been done on thermal comfort in outdoor and semi-outdoor spaces in the city. This study focuses on the analysis and comparison of different passive strategies implemented in courtyards. The present investigation quantifies the comfort improvement brought by shading and misting elements in courtyards. For this purpose, a set of intrinsic and extrinsic variables that intervene in the thermodynamic behavior of the courtyard will be taken into account. The relevance of the study lies not only in the need to design energy-efficient buildings with adequate thermal comfort patterns but also in more resilient urban environments in the current climate change scenario. The main objective of the research is to quantify the implementation of other passive strategies and the results of different combinations of these. The results identified a thermal delta in the courtyard of up to 10°C cooler than the outdoor temperature, which varies depending on the different strategies implemented and the time of day.This work was supported by the grant RTI2018-093521-B-C33 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe” and the Spanish Ministry of Education, Culture and Sports Spain via a pre-doctoral contract granted to V.P. L-C. [FPU17/05036] and E. D-M [FPU18/04783]. The authors gratefully acknowledge AEMET (State Meteorological Agency) for the data supplied.Diz-Mellado, E.; López-Cabeza, V.; Galán-Marín, C.; Rivera-Gómez, C. (2023). Comparative evaluation of passive conditioning strategies for the improvement of courtyard thermal performance. Editorial Universitat Politècnica de València. 658-667. https://doi.org/10.4995/VIBRArch2022.2022.1511265866

Thermal Sensation in Courtyards: Potentialities as a Passive Strategy in Tropical Climates

Climate change will bring changes to our living conditions, particularly in urban areas. Climate-responsive design strategies through courtyards can help to moderate temperatures and reduce the thermal stress of its occupants. Thermal response inside courtyard is affected not only by its morphological composition but also by subjective factors. Thus, standardized thermal scales may not reflect the stress of the occupants. This study investigated the impact on thermal attenuation provided by a courtyard located in a tropical climate under extreme cold and hot synoptic conditions by means of local thermal sensation scales. Microclimatic variables were monitored, simultaneously with the application of a thermal comfort questionnaire, by using weather stations installed outside and inside the courtyard. The Modified Physiological Equivalent Temperature Index (mPET) was utilized to predict the heat stress. Calibration was conducted using linear regression to attribute particular thermal sensation votes to correspondent mPET values. It was found that thermal sensation can be affected by factors such as psychological, behavioral, and physiological. The courtyard’s form provides a passive cooling effect, stabilizing interior thermal sensation, with attenuation peaks of 6.4 °C on a cold day and 5.0 °C on a hot day. Courtyards are an alternative passive strategy to improve thermal ambience in tropical climate, counterbalancing climate change

Unravelling the impact of courtyard geometry on cooling energy consumption in buildings

At present, the energy used for air conditioning in buildings in urban areas accounts for over 36% of total global energy consumption. Energy efficiency has become a critical factor in the urban planning of cities worldwide. Courtyard buildings in hot cities are a prime example of the approach used in traditional vernacular architecture to mitigate the effects of extreme weather. However, given the challenge of guaranteeing accurate modelling of microclimates within these courtyards, their impact on energy demand in buildings has been routinely over-looked by energy certification tools. This work examines three empirical case studies selected in Seville city (Spain), where temperatures during the summer months are extreme. The case studies selected display distinct geometric variations, and the primary objective of the research is to assess the influence of this geometric factor on the cooling energy demand of the building indoors. To achieve this, a validated methodology combining experimental and numerical data was implemented to evaluate the energy performance of buildings with courtyards. Different simulations were conducted to detect the impact of individual courtyard features. The results show a reduction in cooling demand of 8-18% depending on the geometry of the courtyard. Analysis was also carried out on the influence of the floor level and the orientation of adjacent rooms, revealing differences of 15% and 22%, respectively. The main conclusion of the research is that the use of courtyards as functional devices, paying particular attention to their geometry, is a key factor in the cooling energy demand of buildings.13 página

Albedo influence on the microclimate and thermal comfort of courtyards under Mediterranean hot summer climate conditions

The Urban Heat Island (UHI) effect represents a threat to the well-being of cities. Cities must adapt to this phenomenon, prioritizing the improvement of outdoor environment quality. Urban materials have a great impact on outdoor environment quality, energy demand, and citizens’ well-being. Based on the literature, it can be stated that changing the albedo of on-site materials (pavements, facades) is a relevant strategy. The environmental impact of reflective materials from buildings to urban microclimate has been widely discussed in the literature. However, few publications assess the role of albedo in inner courtyards. This work uses simulation results to evaluate the impact of different surface albedo on the thermal performance and comfort of a courtyard in Seville. To do so, the simulation tool ENVI-met, one of the most widely used for outdoor spaces, is validated through a comparison with monitoring results. In conclusion, high reflectance compromises user comfort up to 5 ◦C of PET despite the fact that the use of high albedo on surfaces reduces surface temperature up to 25 ◦C in comparison with low albedo as it accumulates less heat by reflecting more solar radiation. Some of the recommendations given include the use of medium albedo (around 0.4) on walls to balance positive and negative effects, and high albedo on the pavements (above 0.7

Tempering potential-based evaluation of the courtyard microclimate as a combined function of aspect ratio and outdoor temperature

Courtyards are traditional construction models in Mediterranean cities. In this research, tempering performance of courtyards during a two-year field monitoring campaign in southern Spain was investigated. The main objective was to identify the thermal functions of inner courtyards, analyzing the aspect ratio (AR) and the influence of outdoor temperature to offer a perspective that contributes to the development of passive cooling strategies for urban housing. This investigation also reviewed these climate modifiers, in light of the average lifespan of a building, to establish thermal tempering guidelines to mitigate the effects of climate change. The results show that, although the AR is a determining factor in maximizing the courtyard tempering potential, other parameters such as diurnal temperature range (DTR) or maximum outdoor temperature (MOT) can significantly modify the influence of the AR. The study demonstrates these interactions verifying, for the climates studied, that courtyards with AR > 3 are appropriate solutions, especially in the warmest zones, enhancing microclimate management in summer. Results evince that courtyard maximum thermal performance is related to MOT increase. This factor is crucial to establish a tempering initial potential for a given courtyard. Apart from this, a complete daily cycle analysis through DTR confirms and clarifies this thermal buffer effect

Extending the adaptive thermal comfort models for courtyards

Temperatures in Mediterranean cities are rising due to the effects of climate change, with a consequent increase in the heat waves frequency. Recent research has shown the tempering potential of semi-outdoor spaces such as courtyards, which are semi-enclosed spaces that are widely used by the users of buildings in Mediterranean cities. International standards addressing thermal comfort parameters provide technical guidelines for indoor spaces only. Expanding this concept, this paper focuses on the potential to extend and interpret the existing calculation models for indoor thermal comfort, EN 16798 and ASHRAE 55, to determine thermal comfort, monitoring two different courtyards in Cordoba, Spain, during both typical summer and heat wave periods. The results show that during the typical summer, the monitored courtyards can reach temperatures up to 8.4 °C cooler than outside. Subsequently can be considered to be in thermal comfort on average for 88% of the time according to EN 16798, and 75% according to ASHRAE 55, which drop to 71% and 52% respectively during heat wave (HW) periods, in spite of increasing thermal gap (TG) up to 13.9 °C. The results are also compared with the PET indicator used for evaluation of outdoor thermal comfort, which provides comparable figures: 81% summer and 73% HW. Implications of implementing passive shading strategies to increase comfort in these transition spaces are also evaluated. The research highlights the thermal potential and usefulness of courtyards in warm climates, so they can ultimately be included in the building analysis as a potentially comfortable and habitable space

Integrating courtyard microclimate in building performance to mitigate extreme urban heat impacts

Extreme heat events are expected to occur more often as a consequence of climate change. This paper quantifies the impact of urban climate on building performance and evaluates the benefits of specific microclimates, such as inner courtyards, to mitigate extreme heat impacts. A reference case study associated with two outdoor weather conditions, an inner courtyard and a local urban climate, was measured, simulated and validated in TRNSYS. The validated model was then compared to three building models with a single outdoor weather condition associated with the urban climate, weather data from a rural station and a typical year weather file. The models were evaluated in free-running conditions and with air-conditioning systems. The results show how urban climate can increase indoor discomfort hours by 32% in free-running conditions and demonstrate that courtyard microclimate can almost completely mitigate the impact of urban overheating in buildings, eliminating severe indoor discomfort hours by more than 88%. Moreover, the increase in cooling energy demand due to urban climate was reduced by more than 15% in the case of having air-conditioning systems. The findings manifest the importance of accurate weather data for building simulation and demonstrate how multi-nodal outdoor conditions can enable additional strategies to mitigate climate risks, highlighting urban microclimates as a promising strategy to tackle extreme heat events in buildings and citie

Impact of heightwidth proportions on the thermal comfort of courtyard typology for Spanish climate zones

Currently, international organizations such as UN admonish countries to adopt measures facing climate change effects. In the Paris Agreement (Nations, 2015) on climate change, global warming was limited up to 2°C. From the last climate change summit, held in Katowice (Poland) on December 3rd, 2018, the rules for a correct implementation of the Paris Agreement for 2020 were detailed. It is in this context of collective will to reduce the climate change effects, where courtyard acquires a singular meaning, especially in warm climates as the Spanish on