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Mean radiant temperature (MRT), which is a crucial factor for thermal comfort, varies within a space. This renders deriving the representative values for radiant heating and cooling control challenging. This study reviewed existing methods for deriving MRT in previous research and addressed their limitations by proposing a method for determining a representative MRT value. The existing methods were categorized as air temperature, single location, and area weighted. Three methods for deriving representative MRT values were proposed, considering the building's usage, scale, and applicable system installations. The proposed methods were categorized as single-zone averaged, multi-zone averaged, and point-zone MRT. Experiments were conducted by distinguishing cases based on the control of equipment systems during heating and cooling periods. During the cooling season, the single-zone averaged MRT and air temperature differed by up to 4 °C, and the difference between the multi-zone averaged MRT and MRT at a point in the perimeter zone reached up to 7 °C. During the heating season, the single-zone averaged MRT and air temperature differed by up to 2.2 °C. Thus, the results of this study emphasize the importance of applying different methods of deriving representative MRT values depending on the size and usage of the building, and demonstrate that this facilitated more effective heating and cooling control systems. [ABSTRACT FROM AUTHOR]

This study investigates the role of vegetation in enhancing thermal comfort and achieving energy savings in educational building courtyards located in hot, arid climates. The research focuses on an educational building courtyard in New Aswan City, Egypt, and employs a combination of field monitoring and numerical simulations to evaluate the thermal performance of the space. The study utilized the ENVI-met V5.5.1 model for thermal assessment and the Design-Builder software version 6.1.3.007 to quantify the potential energy savings. Nine different vegetation scenarios were proposed and analyzed to identify the most effective strategies for improving the courtyard's thermal conditions. The results demonstrate that a 60% coverage of the courtyard with Cassia Nodosa vegetation produced the most significant improvements. This scenario led to a decrease of over 25.4 °C in physiological equivalent temperature (PET) and a reduction of more than 31.3 °C in mean radiant temperature (Tmrt). Moreover, the energy savings achieved were approximately 19.2%. Interestingly, the study also observed an unexpected decrease in the temperature mitigation efficacy of Ficus nitida when vegetation coverage was increased from 40% to 60%. This phenomenon can be attributed to the complex interplay between the inherent characteristics of the Ficus nitida species and the microclimatic factors within the courtyard environment. These findings provide valuable insights for designers and architects to integrate effective vegetation strategies into the design of educational building courtyards in hot, arid climates. By enhancing thermal comfort and reducing energy consumption, this approach can contribute to the creation of more sustainable and comfortable learning environments. [ABSTRACT FROM AUTHOR]

As populations and temperatures of urban areas swell, more people face extreme heat and are at increasing risk of adverse health outcomes. Radiation accounts for much of human heat exposure but is rarely used as heat metric due to a lack of cost-effective and accurate sensors. To this end, we fuse the concepts of a three-globe radiometer-anemometer with a cylindrical human body shape representation, which is more realistic than a spherical representation. Using cost-effective and readily available materials, we fabricated two combinations of three cylinders with varying surface properties. These simple devices measure the convection coefficient and the shortwave and longwave radiative fluxes. We tested the devices in a wind tunnel and at fourteen outdoor sites during July 2023's record-setting heat wave in Tempe, Arizona. The average difference between pedestrian-level mean radiant temperature (MRT) measured using research-grade 3-way net radiometers and the three-cylinder setup was 0.4 ± 3.0 °C (± 1 SD). At most, we observed a 10 °C MRT difference on a white roof site with extreme MRT values (70 °C to 80 °C), which will be addressed through discussed design changes to the system. The measured heat transfer coefficient can be used to calculate wind speed below 2 m·s−1; thus, the three cylinders combined also serve as a low-speed anemometer. The novel setup could be used in affordable biometeorological stations and deployed across urban landscapes to build human-relevant heat sensing networks. [ABSTRACT FROM AUTHOR]

Semi-private open spaces are indispensable as they enhance society’s growth and contribute to individuals’ health and well-being, thereby improving the quality of life in residential neighbourhoods. However, at present, the integration of such open spaces into the planning of housing projects is often neglected and results in incidental open spaces in the built environment. These incidental open spaces, if designed and integrated carefully, can enhance thermal comfort and community activities significantly. Therefore, this study aims to assess the impact of semi-private open spaces on outdoor thermal comfort in a residential neighbourhood in Kochi, India. A low-rise residential neighbourhood was selected for the study, and the semi-private open spaces were categorized into six typologies based on location, shape, proportions, orientation, aspect ratio, sky view factor, and albedo. Further, the outdoor thermal comfort conditions of these typologies were assessed through simulations in Envi-Met software for a critical summer day. The comfort conditions were assessed through comfort indices namely physiological equivalent temperature and mean radiant temperature (MRT) and were compared to arrive at appropriate design recommendations for semi-private open spaces. The study found a significant correlation between orientation, aspect ratio, sky view factor, and shading with outdoor thermal comfort. The study found a sky view factor of 0.3–0.5, an aspect ratio greater than 1.5, orientation of open spaces in the N-S axis, and shading by trees with canopies above 2.5 m height as appropriate design strategies to reduce the heat stress in semi-private open spaces in low-rise residential neighbourhoods. The study recognizes the importance of integrating planned semi-private open spaces in the local building regulations which can improve the quality of open spaces and enhance public health and well-being while contributing to a better microclimate.

Wind speed is an important variable in the assessment of thermal comfort. Different types of meteorological devices provide different accuracy of air velocity (va) measurements, which under limited air flow conditions, may result in a discrepancy in actual thermal stress level. Simultaneous measurements on warm summer days, performed with a cup anemometer and hot-wire probe, prove that too high starting threshold of the first of these sensors can lead to a discrepancy of actual wind speed, and as a consequence can distort MRT (estimated with globe thermometers) and PET values on average up to 10 °C and 1 °C, respectively. [ABSTRACT FROM AUTHOR]

Cities face the consequences of climate change, specifically the urban heat island (UHI) effect, which detrimentally affects human health. In this regard, deploying PV modules in urban locales prompts inquiry into the impact of energy-active building components on the adjacent thermal microclimate and human thermal comfort. A twofold simulation-based methodology addresses this subject: First, the implications of façade-integrated photovoltaics on the urban thermal microclimate are investigated using a case study in Munich, Germany. Secondly, a parameter study allows us to gain further insights into the relevance of several parameters on the microthermal impact. The simulation results show a daytime heating effect of photovoltaics on the mean radiant temperature of up to +5.47 K in summer and +6.72 K in winter. The increased mean radiant temperature leads to an elevation of the Universal Thermal Climate Index of up to +1.46 K in summer and +2.21 K in winter. During night-time, no increase in both metrics is identified—hence, nocturnal recovery as a key element for human health is not affected. Despite extended human exposure to thermal heat stress in summer, PV façades improve the annual outdoor thermal comfort autonomy by 0.91% due to lower cold stress in winter. The higher PV efficiencies and lower albedo of the reference building surface lower the heating effect. However, with the current efficiencies, PV façades consistently lead to heating of the surrounding thermal microclimate in summer and lower the outdoor thermal comfort. [ABSTRACT FROM AUTHOR]

Urban densities are prone to the urban heat island (UHI) effect, resulting in decreased outdoor thermal comfort for the growing urban populations in hot and dry climates. Canyon layout, surface materials, green cover, and ground moisture can alter the outdoor microclimates of urban canyons at the canopy layer. While the isolated impact of urban cooling strategies is researched extensively, the integration of these UHI mitigation strategies into design compositions for complex projects has yet to be thoroughly examined. This study explores the impact of six different design scenarios for the redevelopment of the entry canyon for the Afifabad garden in Shiraz during the hottest and coldest times of the last decade. The design scenarios include the final proposed and past layouts of the site, along with four interim scenarios introducing feasible compositions of greenery and cool surfaces. The ENVI-met model of the site is validated by field measurement data from 2021, and then used to simulate all six scenarios for the hottest and coldest days of a typical year. The predicted mean vote (PMV) and physiological equivalent temperature (PET) values were calculated from the simulation results and evaluated to identify the most feasible and impactful design compositions. Findings indicate that high albedo pavements were not effective in isolation (scenario 4) and led to an increase in the mean radiant temperature (MRT). Street trees and vegetation were the most influential isolated measures, resulting in a 2.61°C variation in PET. The most impactful results were related to the combined effect of trees, turf, and cool surfaces, which resulted in up to an 11.3°C variation in PET due to the combination of appropriate greenery, shading over surfaces, and cool covers. Understanding the details of the impact of design configurations, when addressing heat stress adaptation in cities, enables the implementation of UHI mitigation strategies into feasible urban retrofit and regeneration projects. [ABSTRACT FROM AUTHOR]

The experimental setup of HVAC testing requires easy but accurate instrumentation, and recent analyses focus on the control based on the mean radiant temperature in order to better perform respect to the users satisfaction. Indeed, the research contribution of this work is the use of Arduino to develop a PID control for an electric heater. As a main feature, this control system can operate by maintaining the set-point on the air temperature or on the mean radiant temperature of the environment where it is placed. The paper describes the design and development of the PID control, as well as the testing of the control system applied to an electric heater, to heat a room in a laboratory in Bologna (Italy). In an Appendix the Matlab script employed to store data on the local pc an to send data to Google Sheets is reported, together with the Google script code employed to write the data from Matlab to the online sheet. As result, the developed PID is accurate in maintaining the required set-point temperature, with minimal deviations from the set-point, in the interval ± 0.2 K. [ABSTRACT FROM AUTHOR]

Mean radiant temperature (MRT), which is a crucial factor for thermal comfort, varies within a space. This renders deriving the representative values for radiant heating and cooling control challenging. This study reviewed existing methods for deriving MRT in previous research and addressed their limitations by proposing a method for determining a representative MRT value. The existing methods were categorized as air temperature, single location, and area weighted. Three methods for deriving representative MRT values were proposed, considering the building’s usage, scale, and applicable system installations. The proposed methods were categorized as single-zone averaged, multi-zone averaged, and point-zone MRT. Experiments were conducted by distinguishing cases based on the control of equipment systems during heating and cooling periods. During the cooling season, the single-zone averaged MRT and air temperature differed by up to 4 °C, and the difference between the multi-zone averaged MRT and MRT at a point in the perimeter zone reached up to 7 °C. During the heating season, the single-zone averaged MRT and air temperature differed by up to 2.2 °C. Thus, the results of this study emphasize the importance of applying different methods of deriving representative MRT values depending on the size and usage of the building, and demonstrate that this facilitated more effective heating and cooling control systems.

This study investigates the role of vegetation in enhancing thermal comfort and achieving energy savings in educational building courtyards located in hot, arid climates. The research focuses on an educational building courtyard in New Aswan City, Egypt, and employs a combination of field monitoring and numerical simulations to evaluate the thermal performance of the space. The study utilized the ENVI-met V5.5.1 model for thermal assessment and the Design-Builder software version 6.1.3.007 to quantify the potential energy savings. Nine different vegetation scenarios were proposed and analyzed to identify the most effective strategies for improving the courtyard’s thermal conditions. The results demonstrate that a 60% coverage of the courtyard with Cassia Nodosa vegetation produced the most significant improvements. This scenario led to a decrease of over 25.4 °C in physiological equivalent temperature (PET) and a reduction of more than 31.3 °C in mean radiant temperature (Tmrt). Moreover, the energy savings achieved were approximately 19.2%. Interestingly, the study also observed an unexpected decrease in the temperature mitigation efficacy of Ficus nitida when vegetation coverage was increased from 40% to 60%. This phenomenon can be attributed to the complex interplay between the inherent characteristics of the Ficus nitida species and the microclimatic factors within the courtyard environment. These findings provide valuable insights for designers and architects to integrate effective vegetation strategies into the design of educational building courtyards in hot, arid climates. By enhancing thermal comfort and reducing energy consumption, this approach can contribute to the creation of more sustainable and comfortable learning environments.

An increase in urban air temperature raises heat stress and mortality risk for city dwellers. This study assessed the potential reductions in air temperature and heat stress through the combined effect of cool façades and floor pavements, in two street canyons in an affordable housing project in Thailand. The air temperature and mean radiant temperatures were simulated for 81 design scenarios where materials with low, medium, and high albedos were used for the walls of buildings, parking areas, and road using ENVI-met v5.0. The risk of exposure to heat stress under extreme conditions was estimated using a heat index equation. The results showed that the avenue canyon (height-to-width ratio, H/W = 0.6) with a low-albedo road surface was hotter than the regular one (H/W = 1.2), due to the larger areas of road pavement and smaller shaded areas. A medium to high albedo for the pavements could reduce the street-level air temperature by up to 2.3°C, but the average mean radiant temperature was raised by 9.3°C. The regular canyon (H/W = 1.2) provided better thermal conditions, and had fewer 'hot spot' areas exposed to heat stress than the avenue canyon. This study explored the benefits of using cool pavements to improve the thermal conditions in areas with limited shade. In addition, this study identified safe outdoor areas not being directly exposed to solar radiation during the hot summer months. These findings could be important for planning safe outdoor activity spaces under extreme heat conditions. [ABSTRACT FROM AUTHOR]

In the face of climate change and rising mean global temperature, urban planning is required to transform cities into resilient living areas for present and future generations. Within this task, microclimate simulation models are an important tool to assess the impact of nature-based solutions (NBSs), building morphology, design of urban quarters, and other measures on the local microclimate. As simulation tools are open to be applied by different user groups, the utilization of the software is often kept as easy as possible. This seeming simplicity bears the risk for users to fall into traps during the model configuration, interpretation of results, or not making use of the full potential of simulations. While scientific literature mainly describes successful application of case studies, it does not cover potential misapplication and related consequences. The present study contributes to closing this research gap and supports the urban planning community with a selection of pitfalls in the model setup and interpretation of results. Clear examples of wrong configuration of wind direction, inaccurate evaluation of mean radiant temperature (MRT), and improper selection of performance indicators are presented by the means of sensitivity experiments and case studies with the modeling software ENVI-Met. The prevailing study demonstrates why MRT values are not suitable to explain effects of NBS during nighttime and contrasts the effects of façade greening on air temperature (0.85°C) with building surface temperature (6.1°C or even 27.5°C with substrate layer). In addition, it highlights the potentials of the multitude of possible performance indicators of microclimate simulations. The selection of avoidable mistakes in the assessment of the local microclimate supports users of microclimate models to promote effective and impactful climate adaption and mitigation measures in urban planning. [ABSTRACT FROM AUTHOR]

School outdoor spaces are important for students as they impact learning outcomes, physical and mental health, social interaction, and overall well-being. In hot, arid climates, the use of outdoor spaces becomes a challenge. The high levels of thermal stress impact outdoor thermal comfort during the warmer months, leading to limited or no use of those spaces. This paper assesses vegetation as a passive cooling strategy for an elementary public school in the city of Riyadh, Saudi Arabia. Air temperature (Ta), mean radiant temperature (Tmrt), and Universal Thermal Climate Index (UTCI) are used to investigate outdoor thermal comfort. The experimental approach adopted in this study compares a base model against eight scenarios, which simulate different vegetation (grass, shrubs, two trees at two different heights, 5-10 m) and spacing between them (3.5 m and 7 m). The data is simulated using Envi-Met 5.5 and assessed for their impact on thermal stress levels for the school outdoor space. The results found that by applying trees 10 m high with 3.5 m spacing between them and using evergreen type leaves, Ta was reduced between (1.4-3.2)°C reaching max reduction in August, Tmrt (7.13-64.73)°C where max reduction was recorded in October, and UTCI at (3.00-17.95)°C in April. Therefore, the study offers solutions for existing schools or future ones to enhance outdoor thermal comfort.

Along with global climate change and urbanisation, the thermal environment is increasingly worse in summer, especially (sub)tropical regions. In recent decades, approaches improving the thermal environment have been frequently investigated. Factors of urban design, planning, and landscaping have been found thermal relevant. These factors were indicated by sky view factor (SVF), vegetation cover, leaf area index (LAI) etc. However, most studies focused one single factor, thermal performance difference between various factors were rarely explored. This study compared park canopy closure (PCC) and LAI about their effects on park thermal comfort indicated by various indices (air temperature, Ta; mean radiant temperature, MRT; and physiological equivalent temperature, PET). The PCC was different from LAI by leaf layer quantity (overlapping). Through a field measurement conducting in 8 parks around Mianyang (a subtropical riverside city, China; summer of 2018). The results revealed, both PCC and LAI were significantly thermal effective, LAI showed less significant thermal effects than PCC in linear models. That is to say, leaf layers had little effect linearly. The effects of PCC on the various indices varied for daily periods, with a significant effect on MRT during the day, Ta in the evening, and PET throughout the day. Increasing PCC from 0 to 1 could reduce PET by 29.44 °C (afternoon, R2 = 0.4928). Findings of this study confirmed the different environmental factors’ impacts on microclimates and distinguished the characteristics of various thermal indices.

Radiant systems are an energy-efficient method for providing cooling to building occupants through active surfaces. To assess the impact of the radiant environment on occupants in space, we develop a ray-tracing simulation, which accounts for longwave radiation. Thermal radiation shares many characteristics with visible light, and thus is highly dependent on surface geometry. Much research effort has been dedicated to characterizing the behavior of visible light in the built environment and its impact on the human experience of space. However, longwave infrared radiation's effect on the human perception of heat is still not well characterized or understood within the design community. In order to make the embodied effect of radiant surfaces' geometry and configuration legible, we have developed a Mean Radiant Temperature (MRT) simulation method, which is based on a ray-tracing technique. It accounts for the detailed geometry of the human body and its surrounding environment. We use a case study of a pavilion built with an envelope consisting of active cooling panels in Singapore. Using measured data for the surrounding surface temperatures in the pavilion, we explore the impact of both the active panels and the surrounding passive elements and thermal environment on a person's radiant heat exchange in different postures. The reflectivity and emissivity values of different surfaces are taken into account, and the ray-tracing process allows for multiple-bounce simulation. The model accounts for both longwave and shortwave radiation, and the simulation results are compared with field measurements for validation. The results are expressed both numerically and as spatial radiant-heat-maps. These show a variation of up to 11°C in MRT across the space studied. Furthermore, a digital manikin is used to assess the impact of the radiant cooling panels across the human body. The results show a 10°C variation in radiant temperature perceived by different regions of the body in one position. The findings reveal a significant heterogeneity of radiant heat transfer that current analysis methods typically overlook for both architectural space and the geometry of the human body. [ABSTRACT FROM AUTHOR]

Mean radiant temperature (MRT) is one of the six primary factors that determine thermal comfort in a given thermal environment. In this study, the average radiant temperature was determined using a calculation method based on the surrounding surface temperatures and view factors. The present study specifically investigated the use of calculated radiant temperature, compared to measured radiant temperature, for predicting the mean vote (PMV) and percentage of dissatisfied (PPD) comfort parameters. The method was validated by the experimental measurements via the black sphere thermometer at five different reference points in a test room, including radiant panels on the ceiling and walls. By using global thermometer measurements, the proposed approach achieved a high degree of compatibility and an accuracy of 0.17 °C, which was the difference between calculated and measured values. The results demonstrated the reliability of the procedure using view factors and surrounding surface temperatures to calculate the radiant temperature in the designated test room; here, a straightforward method for evaluating the thermal conditions of an office room and determining the optimal location of an air temperature sensor in PMV-controlled radiant systems was also proposed. This study contributes to the increasing field of research on thermal comfort and offers knowledge that is beneficial for the design and optimization of indoor environments. [ABSTRACT FROM AUTHOR]

Fine-scale personal heat exposure (PHE) information can help prevent or minimize weather-related deaths, illnesses, and reduced work productivity. Common methods to estimate heat risk do not simultaneously account for the intensity, frequency, and duration of thermal exposures, nor do they include inter-individual factors that modify physiological response. This study demonstrates new whole-body net thermal load estimations to link PHE to heat stress and strain over time. We apply a human-environment heat exchange model to examine how time-varying net thermal loads differ across climate contexts, personal attributes, and spatiotemporal scales. First, we investigate summertime climatic PHE impacts for three US cities: Phoenix, Miami, and New York. Second, we model body morphology and acclimatization for three profiles (middle-aged male/female; female >65 years). Finally, we quantify model sensitivity using representative data at synoptic and micro-scales. For all cases, we compare required and potential evaporative heat losses that can lead to dangerous thermal exposures based on (un)compensable heat stress. Results reveal misclassifications in heat stress or strain due to incomplete environmental data and assumed equivalent physiology and activities between people. Heat strain is most poorly represented by PHE alone for the elderly, non-acclimatized, those engaged in strenuous activities, and when negating solar radiation. Moreover, humid versus dry heat across climates elicits distinct thermal responses from the body. We outline criteria for inclusive PHE evaluations connecting heat exposure, stress, and strain while using physiological-based methods to avoid misclassifications. This work underlines the value of moving from "one-size-fits-all" thermal indices to "fit-for-purpose" approaches using personalized information. [ABSTRACT FROM AUTHOR]

Local parks are widely used to mitigate urban heat islands. However, the increase of dry weather periods in subtropical climates has caused natural grass failure, leading some city councils to replace it with artificial grass. Therefore, this study investigates various local park settings to assess the performance of different ground covers (i.e., irrigated and non-irrigated natural grass, bare soil, and artificial grass) and the influence that tree proximity has on them, as well as the total thermal performance of the investigated local parks. This study finds that non-irrigated parks could harm park users’ health due to the high concentration of mean radiant temperature (MRT) around trees. Although the surface temperature of the artificial grass was higher (2.60 °C) than that of asphalt during periods of peak temperature, the parks using artificial grass performed better at reducing air temperature and enhancing thermal comfort than the ones with dry grass or bare soil, where both tree proximity and soil water content played significant roles. However, artificial grass negatively affected night cooling, resulting in a poorer daily performance. This study discusses the influence of various park settings on air temperature, MRT, thermal comfort, surface temperature, soil temperature, and water content. In addition, various recommendations and settings are offered to direct decision makers and future studies.

Cities face the consequences of climate change, specifically the urban heat island (UHI) effect, which detrimentally affects human health. In this regard, deploying PV modules in urban locales prompts inquiry into the impact of energy-active building components on the adjacent thermal microclimate and human thermal comfort. A twofold simulation-based methodology addresses this subject: First, the implications of façade-integrated photovoltaics on the urban thermal microclimate are investigated using a case study in Munich, Germany. Secondly, a parameter study allows us to gain further insights into the relevance of several parameters on the microthermal impact. The simulation results show a daytime heating effect of photovoltaics on the mean radiant temperature of up to +5.47 K in summer and +6.72 K in winter. The increased mean radiant temperature leads to an elevation of the Universal Thermal Climate Index of up to +1.46 K in summer and +2.21 K in winter. During night-time, no increase in both metrics is identified—hence, nocturnal recovery as a key element for human health is not affected. Despite extended human exposure to thermal heat stress in summer, PV façades improve the annual outdoor thermal comfort autonomy by 0.91% due to lower cold stress in winter. The higher PV efficiencies and lower albedo of the reference building surface lower the heating effect. However, with the current efficiencies, PV façades consistently lead to heating of the surrounding thermal microclimate in summer and lower the outdoor thermal comfort.

This paper focuses on the impact of three types of roof retrofitting: green, high albedo-coated, also called ‘cool roofs’, and recently developed ‘super cool’ materials—in mitigating the effects of summer urban heat islands (UHI) and enhance overall urban thermal comfort. Human thermal comfort was considered in terms of physiologically equivalent temperature (PET), calculated by combining on-site field measurements with ENVI-met microclimate modelling and the RayMan model. The main environmental parameters addressed were roof surface temperature, ambient air temperature, and mean radiant temperature. The results show that the performance of the super cool roofs surpassed the cool and green roofs at reducing average ambient air and mean radiant temperatures, and the super cool roof had the lowest average PET during the day. However, all the roofs shortened the duration of strong thermal stress by 1 h compared to the conventional roof. This work contributes to the understanding of how roof retrofit technologies can be evaluated at the neighbourhood scale, assisting strategic decisions on building envelope retrofitting for sustainable cities.

The standard for ergonomics of the thermal environment provides information on the calculation of optimal thermal comfort. Operative temperature (OT) is one of the essential elements of thermal comfort and is a function of air temperature, mean radiant temperature (MRT), and air velocity. This paper investigates the impact of diverse influences on MRT in an office room based on occupant position and posture (seated and standing). A comparative simulation study of the varied thermal transmittance (U-value) of the only external wall with a window in an office room depending on the wide-ranging outdoor temperature is conducted in the MATLAB tool Simulink. The air temperature and air velocity are assumed according to the standards, and the MRT is simulated. The angle factors, U-value of walls/windows, occupant position, occupant posture, and outdoor temperature are the critical parameters that affect MRT. The results show varied responses from MRT for each of the five outdoor temperature scenarios simulated for three types of exterior walls. Seated occupants have equal MRT, whereas standing occupants have minor discrepancies when exposed to a window at the same distance in all outdoor scenarios. When the placement of occupants is not equally exposed to the window, the seated occupants have a higher MRT difference than the standing occupants. [ABSTRACT FROM AUTHOR]

W analizie bilansu cieplnego człowieka największym problemem jest określenie ilości promieniowania pochłoniętego przez człowieka. Dlatego też w badaniach komfortu cieplnego stosuje się uproszczenia i jako miarę termicznego wymiaru pola promieniowania wokół człowieka stosuje się koncepcję średniej temperatury promieniowania - Mrt (Mean radiant temperature), która traktuje łącznie wszystkie strumienie promieniowania długo-i krótkofalowego, na które eksponowane jest ludzkie ciało. Na terenach zurbanizowanych do określenia wartości Mrt sugeruje się prowadzenie bezpośrednich pomiarów tego parametru. Najczęściej wykorzystuje się do tego termometr kulisty - z uwagi na prostotę jego konstrukcji, niski koszt oraz łatwość użytkowania. Celem pracy jest zweryfikowanie przydatności termometrów kulistych do pomiarów Mrt, określenie zależności ich wskazań od wartości parametrów meteorologicznych oraz ustalenie wpływ sposobu oszacowania Mrt na wartości wskaźnika UTCI (Universal Thermal Climate Index). Do wyznaczenia Mrt użyto trzech termometrów kulistych: jeden standardowy 15-centymetrowy (SGT) oraz dwa 4-centymetrowe akrylowe (AGT) własnej konstrukcji. Badania wykonano na terenach otwartych oraz w cieniu drzew. Typ zastosowanego instrumentu pomiarowego istotnie wpływa na wielkość Mrt w warunkach silnego usłonecznienia - najwyższe wartości Mrt uzyskano za pomocą SGT, a najniższe przy pomocy szarego AGT. W cieniu wszystkie typy przyrządów wskazywały zbliżone do siebie wartości. Błąd oszacowania UTCI w efekcie niepewności wyznaczonych wartości Mrt za pomocą różnych termometrów kulistych, odpowiada jednej kategorii stresu termicznego w warunkach radiacyjnych, natomiast w cieniu jest zaniedbywalny. [ABSTRACT FROM AUTHOR]

Local parks are widely used to mitigate urban heat islands. However, the increase of dry weather periods in subtropical climates has caused natural grass failure, leading some city councils to replace it with artificial grass. Therefore, this study investigates various local park settings to assess the performance of different ground covers (i.e., irrigated and non-irrigated natural grass, bare soil, and artificial grass) and the influence that tree proximity has on them, as well as the total thermal performance of the investigated local parks. This study finds that non-irrigated parks could harm park users' health due to the high concentration of mean radiant temperature (MRT) around trees. Although the surface temperature of the artificial grass was higher (2.60 °C) than that of asphalt during periods of peak temperature, the parks using artificial grass performed better at reducing air temperature and enhancing thermal comfort than the ones with dry grass or bare soil, where both tree proximity and soil water content played significant roles. However, artificial grass negatively affected night cooling, resulting in a poorer daily performance. This study discusses the influence of various park settings on air temperature, MRT, thermal comfort, surface temperature, soil temperature, and water content. In addition, various recommendations and settings are offered to direct decision makers and future studies. [ABSTRACT FROM AUTHOR]

Increasing heat in urban areas raises heat-related health risks. Green infrastructure and managing surface albedo can reduce the radiation exposure of pedestrians. However, selecting options among various radiant fluxes mitigation strategies is challenging, particularly due to potential interactions among options such as planting vegetation or changing surface albedos. We used a multi-strategies model for determining optimal design combinations for reducing mean radiant temperature (MRT) in urban environments across a range of costs and benefits. The solutions are developed by a non-dominated sorting genetic algorithm II (NSGA II) with a MRT simulator. We selected four MRT reduction strategies: tree planting, grass planting, albedo reduction of building walls, and albedo reduction of sidewalks. Model test results for a simulated street canyon show a wide range of optimal alternative plans considering the combination effects of the four strategies. While previous studies have focused on single options to reduce heat load, we found benefits were higher by using a combination of these strategies, which can provide synergistic benefits. These results provide useful information for decision makers confronting real world problems such as heat related mortality. Thermal-friendly design methods and green infrastructure will help the urban environment become sustainable and improve human health and well-being.

The paper examines outdoor thermal comfort in summer in the multi-family housing area Duvanište in the city of Niš, Serbia, combining objective and subjective evaluation assessments. Objective evaluation obtained field measurements of microclimatic parameters at selected sites and mean radiant temperature, predicted mean vote, and psychological equivalent temperature calculation using RayMan software. Subjective methodology assessment is performed using survey questionnaires based on thermal sensation vote and overall comfort vote. The paper aims to find the correlation between measured and calculated parameters on one side and Thermal Sensation Vote values. The results show that air temperature signifi- cantly correlates to human thermal sensation in the subject area. Obtained results also indicate high prediction accuracy of psychological equivalent temperature in the outdoor thermal comfort evaluation in summer. Finally, to feel comfortable, neither warm nor cold, in continental climate regions with hot summer conditions, the neutral psychological equivalent temperature should be between 15-24.3 °C. [ABSTRACT FROM AUTHOR]

A crucial variable to evaluate thermal comfort is the mean radiant temperature (Tmrt). In this paper we evaluate the performance of the 150 mm black globe thermometer to provide reliable Tmrt values for outdoor settings in Singapore. Accurate Tmrt values are calculated by the method of integral radiation measurements. Based on these, the mean convection coefficient of the black globe has been re-calibrated. Results show an improvement in the estimation of Tmrt with the new coefficient in comparison with the default version suggested in ISO7726:1998. Increasing the averaging periods of the measured variables improved the performance of the derived mean convective coefficients to estimate Tmrt. During clear skies day and for 10-min averaged data, RMSE for Tmrt reduce to 3.9 °C (7.4 °C for ISO7726:1998 coefficient) with an overestimation on high incoming solar radiation periods and an underestimation during the morning and evening (low solar elevation). During overcast dry conditions an underestimation of Tmrt is also expected which is higher in the rain/wet periods. The mean convective coefficient presented in this work can provide improved estimations of Tmrt relevant for outdoor thermal comfort studies in hot and humid tropical climates like Singapore. [ABSTRACT FROM AUTHOR]

An increase in urban air temperature raises heat stress and mortality risk for city dwellers. This study assessed the potential reductions in air temperature and heat stress through the combined effect of cool façades and floor pavements, in two street canyons in an affordable housing project in Thailand. The air temperature and mean radiant temperatures were simulated for 81 design scenarios where materials with low, medium, and high albedos were used for the walls of buildings, parking areas, and road using ENVI-met v5.0. The risk of exposure to heat stress under extreme conditions was estimated using a heat index equation. The results showed that the avenue canyon (height-to-width ratio, H/W = 0.6) with a low-albedo road surface was hotter than the regular one (H/W = 1.2), due to the larger areas of road pavement and smaller shaded areas. A medium to high albedo for the pavements could reduce the street-level air temperature by up to 2.3°C, but the average mean radiant temperature was raised by 9.3°C. The regular canyon (H/W = 1.2) provided better thermal conditions, and had fewer ‘hot spot’ areas exposed to heat stress than the avenue canyon. This study explored the benefits of using cool pavements to improve the thermal conditions in areas with limited shade. In addition, this study identified safe outdoor areas not being directly exposed to solar radiation during the hot summer months. These findings could be important for planning safe outdoor activity spaces under extreme heat conditions.

The high temperature and humidity make Southeast Asia (SEA) one of the regions most susceptible to the occurrence of thermal discomfort days (TDDs) in the world. In the context of global warming, SEA’s rapid population growth and urban expansion further exacerbated the region’s exposure to TDD, posing greater risks in public health. However, there exists a significant knowledge gap in the understanding of the long-term spatiotemporal evolution of TDD, as well as its projection in the future. By utilizing the newly released ERA5 datasets of Universal Thermal Climate Index (UTCI) and Mean Radiant Temperature (MRT), this study presented the 81-year analysis of TDDs in SEA countries, spanning from 1940 to 2020, with projections extending to 2100. While the mean increase in UTCI was relatively modest, the corresponding rise in TDD likelihood was disproportionately larger, indicating a heightened risk of exposure. A distinct contrast was observed between continental and maritime regions, with maritime countries showing smaller absolute rises in both indices but larger trends in TDD frequency due to oceanic moderating effects. Seasonal analyses highlighted the dominant influence of the East Asia monsoon over SEA, and spatial analyses revealed a negative correlation between TDD occurrence and elevation, with low-lying areas being hotspots. Projections for 2050 suggest continued warming. These findings underscore the urgency of proactive measures to address climate change impacts, particularly in vulnerable maritime and low-lying areas, providing valuable insights for enhancing climate resilience and adaptation in SEA. Our findings reveal critical insights into the trends and future scenarios of thermal discomfort in the region, underscoring the urgent need for effective climate adaptation strategies.

We assessed the difference between mean radiant temperature ((t_r ) ̅) and air temperature (t_a) in conditioned office buildings to provide guidance on whether practitioners should separately measure (t_r ) ̅ or operative temperature to control heating and cooling systems. We used measurements from 48 office buildings in the ASHRAE Global Thermal Comfort Database, five field studies in radiant and all-air buildings, and five test conditions from a laboratory experiment, including both radiant and all-air spaces. Considering only the ASHRAE Global Thermal Comfort Database because it is the largest and most representative dataset, under typical office conditions, the median absolute difference (e.g., disregarding direction of the difference) between (t_r ) ̅ and t_a was 0.4 ℃ (with interquartile range = 0.4 ℃), and more specifically, the median difference shows that (t_r ) ̅ was 0.4 ℃ (with interquartile range = 0.4 °C) warmer than t_a. In the radiant cooled laboratory tests, (t_r ) ̅ was significantly (p

Extreme heat is a current and future issue on urban areas, with negative impacts on health and quality of life (increasing morbidity and mortality rates). This paper analyses day (12:00–15:00 h) and nighttime (00:00–03:00 h) thermo-physiological comfort (TC) conditions by Local Climate Zones (LCZ) in Lisbon during a particular Local Weather Type (LWT), very hot summer days. For this, 13 different microscale sample areas were chosen covering urban and non-urban land cover classes (LCZs 1–3, 4–6, 8, 9, A and B). Universal Thermal Climate Index (UTCI) and Mean Radiant Temperature (MRT) were modeled on SkyHelios software for 163 days between 2008 and 2014. Results show that during the day all urban LCZ samples depict the same average TC conditions (average UTCI of 34°C—strong heat stress) and densely wooded areas are 2°C cooler (average UTCI of 32°C—moderate heat stress). However, compact areas (LCZs 1–3) with low sky view factor and some vegetation (street trees) display lower percentages of area with higher thermo-physiological discomfort (TD) levels (83% with strong heat stress against 98% in LCZs 8 and 9 and 100% in LCZs 4–6). When considering the hottest days (air temperatures equal or above 35°C—75th percentile), the moderate heat stress class disappears in all samples and the very strong heat stress class appears only on urban areas, occupying between 12% and 16% on LCZs 1–3, 10%–22% on LCZs 4–6, 16%–22% on LCZs 8 and 9 on LCZ 9. During the nighttime period all samples show no thermal stress, favoring nocturnal physiological recovery. TC conditions in Lisbon are strongly influenced by solar radiation and wind, which explains the need to increase the shading area, preferably by trees, and to promote and preserve ventilation paths.

Mean radiant temperature (MRT) is important for indoor thermal comfort determination. Several good ways to practically obtain accurate MRT include measuring all indoor surface temperatures for MRT calculation or using a black globe thermometer. Still, it can be hard to apply in practice because using such experimental measurements increases the efforts of data management times and acquisition costs. In this regard, there is a practical advantage in reducing the number of measured surfaces by grouping similar surfaces rather than measuring all indoor surface temperatures individually to obtain MRT. However, since even those similar surfaces are not the same, it can lead to erroneous MRT estimation, which needs to be investigated. This study analyzes the uncertainty of MRT estimates by categorizing the surfaces with similar temperature behaviors to examine the risk of such inaccuracy. In this study, the input data required for the MRT calculation are generated using a measurement data-based simulation model, and the uncertainty of the MRT is quantified using the Monte Carlo method. As a result of the study, it is observed that excluding surfaces with similar temperatures for MRT estimation does not significantly affect the uncertainty. When the appropriate number of input surfaces is satisfied, its MRT shows a difference of less than 1% compared to the results calculated with all surfaces. [ABSTRACT FROM AUTHOR]

The Wet Bulb Globe Temperature (WBGT) is an international standard heat index used by the health, industrial, sports, and climate sectors to assess thermal comfort during heat extremes. Observations of its components, the globe and the wet bulb temperature (WBT), are however sparse. Therefore WBGT is difficult to derive, making it common to rely on approximations, such as the ones developed by Liljegren et al. (2008, https://doi.org/10.1080/15459620802310770, WBGTLiljegren ${\mathrm{W}\mathrm{B}\mathrm{G}\mathrm{T}}_{\mathrm{L}\mathrm{i}\mathrm{l}\mathrm{j}\mathrm{e}\mathrm{g}\mathrm{r}\mathrm{e}\mathrm{n}}$) and by the American College of Sports Medicine (WBGTACSM87 ${\mathrm{W}\mathrm{B}\mathrm{G}\mathrm{T}}_{\mathrm{A}\mathrm{C}\mathrm{S}\mathrm{M}87}$). In this study, a global data set is created by implementing an updated WBGT method using ECMWF ERA5 gridded meteorological variables and is evaluated against existing WBGT methods. The new method, WBGTBrimicombe ${\mathrm{W}\mathrm{B}\mathrm{G}\mathrm{T}}_{\mathrm{B}\mathrm{r}\mathrm{i}\mathrm{m}\mathrm{i}\mathrm{c}\mathrm{o}\mathrm{m}\mathrm{b}\mathrm{e}}$, uses globe temperature calculated using mean radiant temperature and is found to be accurate in comparison to WBGTLiljegren ${\mathrm{W}\mathrm{B}\mathrm{G}\mathrm{T}}_{\mathrm{L}\mathrm{i}\mathrm{l}\mathrm{j}\mathrm{e}\mathrm{g}\mathrm{r}\mathrm{e}\mathrm{n}}$ across three heatwave case studies. In addition, it is found that WBGTACSM87 ${\mathrm{W}\mathrm{B}\mathrm{G}\mathrm{T}}_{\mathrm{A}\mathrm{C}\mathrm{S}\mathrm{M}87}$ is not an adequate approximation of WBGT. Our new method is a candidate for a global forecasting early warning system. Plain Language Summary: The Wet Bulb Globe Temperature (WBGT) is an international standard for how we measure the effect of heat on the human body. It is used across sectors in health, industry, sports, and climate to calculate how we feel and how our body responds during heat extremes. Its calculation has historically relied on globe thermometer and wet bulb temperature observations, which are however not widely available. This has made WBGT difficult to calculate and meant approximations have been created. Here we formulate a new WBGT method that can be used with global gridded data that are freely available and we compare it against other methods in common use. We find that our method is accurate when compared to the existing gold standard WBGT method. Key Points: We create an accurate method for calculating Wet Bulb Globe Temperature (WBGT) using Mean Radiant Temperature termed WBGTBrimicombeIt is found that WBGTamsc87 also known as WBGTsimple is not an accurate approximation of WBGTWBGTBrimicombe can assist with robust heat stress standards across sectors including in public and occupational health [ABSTRACT FROM AUTHOR]

Heating the whole space, which is currently used in northern China, leads to high energy consumption and substantial pollution. A transition to local heating has the potential to help address this problem. In this paper, the effects of radiator-related parameters (position, power, and size) and room-related parameters (aspect ratio and height) on local heating were studied. Two evaluation indices, the effective coefficient of operative temperature (OTEC) and the effective coefficient of local heating (LHEC), were proposed. In addition, the heat source-control core-area (HSCCA) was proposed, and the effect range of heat sources in the space was evaluated by the attenuation of operative temperature. The findings demonstrated that the radiator position has a greater influence on local heating than size. When the position of the radiator was changed from "close to the inner wall" to "close to the outer wall", the LHEC (the interior one-quarter of room is a local heating zone) was found to decrease by 73%. The size of the radiator, which is close to the inner wall, doubled or quadrupled, and the LHEC increased by 9% and 18%. Moreover, rooms with a larger aspect ratio or small room height were found to be the most optimal for local heating applications. The area of the HSCCA decreased as the position of the radiator approached the outer wall. The findings of this study can be used as a design reference for the radiator when the heating mode changes from "full-space heating" to "local heating". [ABSTRACT FROM AUTHOR]

Efficient cooling and heating solutions for nearly zero-energy solar dwellings are required to mitigate climate change and to make dwellings sustainable. The installed pipeline for a radiant heating system, which is only used for space heating when heating is necessary, can also be used to cool the room with only the enthalpic use of natural city water by releasing the natural city water through the embedded pipeline already installed for radiant heating. Natural city water used for radiant cooling can be used in necessary locations such as for toilets, washing cars, laundry facilities, and garden water, which corresponds to approximately 56% of the water we use at home. As a result, the embedded pipes that make up a radiant heating system can be converted to a passive intelligent radiant cooling system with minimal added installation and control systems. Thermal comfort and behavior analyses in an enclosure with a radiant cooling system are fulfilled through experimentation, mean radiant temperature simulation, and asymmetric radiation calculation. No uncomfortable asymmetric radiation is encountered during the cooling period, so the cooling spaces are well controlled within the comfortable cooling range. A passive intelligent radiant cooling system that uses just the enthalpy of natural city water can be an appropriate ecological solution to better develop zero-energy dwellings. No extra cooling energy and power are required to cool a space that uses just enthalpy and pressure from natural city water. [ABSTRACT FROM AUTHOR]

• Introduced WebMRT, an online T mrt prediction tool using tree-based ensemble models. • Trained on state-of-the-art measurements collected using Marty in Southwest US. • LightGBM achieved R2=0.92, RMSE=3.43, MAPE=5.33, and MBE = 0.20. • Streamlined process from input to T mrt prediction for wider stakeholder engagement. • Designed with simplicity to enhance data-driven urban climate governance. Mean Radiant Temperature (T mrt) is the most critical atmospheric variable influencing outdoor human thermal exposure and comfort in hot, dry environments. However, accurately quantifying T mrt requires time-consuming field measurements with expensive equipment or complex, resource-intensive computations. We introduce WebMRT, an online tool to predict T mrt using a data-driven approach. It features an intuitive interface using air temperature, shading status, and built environment features as predictors of T mrt for a user-selected summer day, time, and location. Utilizing a tree-based ensemble model, WebMRT is trained on state-of-the-art human-biometeorological data collected by MaRTy using LightGBM after evaluating its performance against several candidate machine learning regressors. Feature engineering was applied to the day and time input, and two additional temporal features were derived: 'Solar Altitude' and 'Minutes-from-Sunrise'. These inputs are integrated into the user interface, emphasizing simplicity and easy access for users at the frontend. After training the regressor on MaRTy datasets and employing k-fold cross-validation with ten folds, the model demonstrated strong predictive power (R2=0.92) with acceptable error (RMSE=3.43, MAPE=5.33) and bias (MBE=0.20). WebMRT also features optional fisheye photo uploads, processed using transfer learning techniques for image segmentation, further enhancing the tool's predictive accuracy, user experience, and applications towards climate action decision-making processes. [ABSTRACT FROM AUTHOR]

• Trees' cooling impact varies with placement near buildings. • Small trees can cool as effectively as large ones if correctly placed. • Distant trees lower mean radiant temperature by over 20 °C in high-rise complexes around noon. • The cooling effect changes with tree distance from shaded walls. • Tree-cooling effectiveness decreases by 71 % to 91 % based on location. Street trees are vital in mitigating urban heat islands, with their cooling effect significantly influenced by the urban layout. Past studies explored how urban canyon characteristics—aspect ratio, building coverage—affect tree cooling, yet seldom analyzed the impact of distance between trees and buildings. Addressing this, our study evaluates tree cooling effects concerning their proximity to shaded and sunlit walls. The findings highlight that cooling effectiveness varies with the ratio of distance from the shaded wall to building height (D s h a :H), peaking within a ratio range of 0.55 to 0.7. Below a ratio of 0.3, effectiveness decreases to 9–29 %, emphasizing the importance of strategic planting distances. The result shows that when planted at an optimal distance from buildings, small trees can produce similar radiation mitigation effects to those of larger trees. This discovery advocates for thoughtful tree placement in high-density areas, optimally leveraging their shade and evapotranspiration benefits. The study provides actionable insights for urban planners and landscape architects, suggesting that careful consideration of tree placement relative to building shadows can significantly improve urban climates, offering a strategic approach to deploying green infrastructure in high-rise complexes for enhanced climate resilience. [ABSTRACT FROM AUTHOR]

• Radiant and air systems were compared at 26 °C and benchmarked against 23 °C. • Both systems produced similar thermal conditions with a difference in air velocity. • The radiant system extracted 33% more heat from space than the air system. • At 26 °C, the radiant system consumed 4 % less energy than the air system. • 60% of participants were satisfied with the thermal environment in both systems. In an experimental study set in Singapore's tropical climate, we evaluated the thermal environmental performance, energy consumption, and thermal comfort of air and radiant cooling systems, operating at an operative and air temperature of 26 °C. 78 participants across five groups answered thermal comfort surveys in a crossover study design. Environmental performance metrics indicated that both systems produced similar conditions, with a noticeable difference in air velocity. The mean radiant temperature to air temperature difference was less than 0.5 °C in both systems. The radiant system exhibited a 33 % higher heat flux extraction than the air system and required less electrical power for the transportation of the cooling medium and ventilation air. Overall, the radiant system used 4 % less energy than the air system when controlled at 26 °C and 34 % when operated at 23 °C. Results show that radiant and air systems provided equal thermal comfort in cooling, with over 60 % of participants expressing satisfaction and ∼ 20 % voted neutral thermal satisfaction. ∼ 40 % of participants preferred cooler conditions, and ∼ 30 % desired increased air movement. [ABSTRACT FROM AUTHOR]

Mean radiant temperature (MRT) is one of the six primary factors that determine thermal comfort in a given thermal environment. In this study, the average radiant temperature was determined using a calculation method based on the surrounding surface temperatures and view factors. The present study specifically investigated the use of calculated radiant temperature, compared to measured radiant temperature, for predicting the mean vote (PMV) and percentage of dissatisfied (PPD) comfort parameters. The method was validated by the experimental measurements via the black sphere thermometer at five different reference points in a test room, including radiant panels on the ceiling and walls. By using global thermometer measurements, the proposed approach achieved a high degree of compatibility and an accuracy of 0.17 °C, which was the difference between calculated and measured values. The results demonstrated the reliability of the procedure using view factors and surrounding surface temperatures to calculate the radiant temperature in the designated test room; here, a straightforward method for evaluating the thermal conditions of an office room and determining the optimal location of an air temperature sensor in PMV-controlled radiant systems was also proposed. This study contributes to the increasing field of research on thermal comfort and offers knowledge that is beneficial for the design and optimization of indoor environments.

During daylight hours, the mean radiant temperature Tmrt$T_{\text{mrt}}$ is one of the most important meteorological parameters to analyse heat stress for humans. This study conducts a spatio-temporal analysis of Tmrt$T_{\text{mrt}}$ for a summer period in 2018 for the city of Berlin, Germany. To this end, the mesoscale climate model COSMO-CLM (CCLM) is coupled with the urban Double Canyon Effect Parameterization scheme with a building energy model (DCEP–BEM) to derive Tmrt$T_{\text{mrt}}$. This coupled model system CCLM/DCEP–BEM enables a dynamic calculation of Tmrt$T_{\text{mrt}}$ for the microscale urban street canyons using a mesoscale model. To bring a more accurate comparison, a two-step approach is applied to assess the radiative fluxes and Tmrt$T_{\text{mrt}}$ from CCLM/DCEP–BEM. The radiation model SOLWEIG is first validated against measurement and then used to evaluate the DCEP–BEM model. Overall good agreement in Tmrt$T_{\text{mrt}}$ is found between CCLM/DCEP–BEM and SOLWEIG (R2=0.96$\text{R}^2 =\nobreak 0.96$). Nighttime Tmrt$T_{\text{mrt}}$ simulated with CCLM/DCEP–BEM is higher than that with SOLWEIG (MBE=2.9K$\text{MBE}=\nobreak 2.9\,\text{K}$), yet closer to measurements. Tmrt$T_{\text{mrt}}$ during the afternoon hours modeled with CCLM/DCEP–BEM is underestimated compared to SOLWEIG (MBE=-3.1K$\text{MBE}=\nobreak -3.1\,\text{K}$). Further, excluding vegetation, higher values for nighttime Tmrt$T_{\text{mrt}}$ are found in the densely built-up city center than in the suburbs with more open structures, while the city center has lower values for Tmrt$T_{\text{mrt}}$ during midday. This study provides a reliable representation of Tmrt$T_{\text{mrt}}$ in a mesoscale model and would be beneficial for future implementation of human-biometeorological variables such as the Universal Thermal Climate Index or Physiological Equivalent Temperature. These quantities are calculated using Tmrt$T_{\text{mrt}}$.

[Display omitted] • Existing mean radiant temperature inaccurately accounts for radiant heat dissipation of human body. • Proposed mean radiant temperature accurately accounts for radiant heat dissipation of human body. • Existing mean radiant temperature results in overlarge errors in thermal comfort evaluation. • Proposed mean radiant temperature can be used for accurate thermal comfort evaluation. Low-emissive coatings applied to the inner surfaces of the envelope effectively reduce the energy consumption of buildings, but significantly affect the radiant heat dissipation (RHD) of the human body. The mean radiant temperature (MRT) from the existing method cannot accurately estimate the RHD of the human body, which deteriorates thermal comfort thereby impeding the application of low-emissive coatings. This study proposes a calculation method of the MRT which accurately estimates the RHD of the human body. Case studies demonstrate that with the emissivity of the inner surfaces of the envelope decreasing from 0.9 to 0.1, the existing method inaccurately estimates the RHD of the human body with an error of up to 132%, while the proposed method reduces the error to less than 2.5%. The MRT from the existing method results in an error in thermal comfort evaluation (indicated by Predicted Mean Vote) up to 0.31 which fails the desired accuracy. The MRT from the proposed method effectively reduces the error in thermal comfort evaluation to be less than 0.01 satisfying the desired accuracy. Therefore, the proposed method contributes to the development of thermally comfortable and energy-efficient indoor environments with low-emissive coatings. [ABSTRACT FROM AUTHOR]

Ongoing climate change is manifesting in the expansion of the urban heat island (UHI) effect. This paper evaluates the microclimate benefits of cool pavements and green infrastructures in a historical square in Rome, Italy. The ENVI-Met software enabled us to conduct a microclimatic analysis of the examined square in July 2021, through a comparison of the thermal performances of the current asphalt and sampietrini pavement (AS) with three alternatives. The proposed options are to change the existing layout to include: light concrete slabs and green furniture consisting of 5 m high trees (LC+G1), a perimeter hedge with 5 m high trees (LC+G2), and a perimeter hedge with 15 m high trees (LC+G3). The effects of the road pavements as passive countermeasures to the UHI effect are investigated in terms of air temperature (AT), mean radiant temperature (MRT), and predicted mean vote (PMV). The results show that the existing asphalt pavement is the worst option, while the cool pavement integrated with vegetation is greatly beneficial to human thermal comfort. Compared to the current layout, LC+G3 is the best scenario, because it implies an AT reduction higher than 3 °C, a MRT reduction equal to 50%, and a maximum PMV value equal to 2.2. [ABSTRACT FROM AUTHOR]