Article

The spatial comfort and thermal delight of outdoor misting installations in hot and humid extreme environments

Authors:
If you want to read the PDF, try requesting it from the authors.

Abstract

Within the boundaries of Climate Change, existing hot and humid climates will likely become more extreme calling for research into solutions that allow for the thermal liveability of such places. To this extent, there is literature advocating for exploring evaporative cooling in hot and humid climates, having recorded that when fine mist is deposited on skin, thermal comfort can be achieved. However, there is only a handful of studies involved with misting prototypes efficacy in such contexts. An experimental study was thus conducted to explore simple mist cooling technologies impact on outdoor comfort. A full-scale misting prototype was built in the city of Antofagasta, located in the desert of Chile, and experiencing high humidity and massive solar radiation. The generated environmental conditions were measured, and thermal comfort questionnaires used to supplement quantitative data interpretation with information on the levels of comfort achieved. The experiment demonstrated the potential of mist cooling in this environment, which led to a significant reduction in air temperature, mean radiant temperature and thus on the universal thermal climate index, without significant increases in ambient humidity. Results showed over a 15°C cooling effect in all three metrics at peak times, and occupants consistently reported a cooling effect after spending time within the mist.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Seven articles evaluated public misting stations designed to cool places and people via water droplets during extreme heat events. Misting stations were located in Osaka, Japan [31], Ancona and Rome, Italy [32][33][34], Singapore [35], Antofagasta, Chile [36], and Tempe, Arizona [37]. Evaluations were supported by a variety of metrics captured by sensors, indices, meteorological data, and comfort surveys administered to participants, and they measured participants' physiological responses to the misting system. ...
... In the second iteration, the system was programmed to regulate misting based on weather conditions [33,34]. In Antofagasta, Chile, a misting station prototype with the capacity for direct and indirect misting was installed in a particularly hot location with mostly dark surfaces and little shade [36]. While the station is not referred to as a 'dry' misting system, authors emphasize that the prototype was designed to emit fine droplets of water to avoid leaving participants feeling damp after using the station [36]. ...
... In Antofagasta, Chile, a misting station prototype with the capacity for direct and indirect misting was installed in a particularly hot location with mostly dark surfaces and little shade [36]. While the station is not referred to as a 'dry' misting system, authors emphasize that the prototype was designed to emit fine droplets of water to avoid leaving participants feeling damp after using the station [36]. The study in Osaka, Japan, set up a spray station consisting of eight nozzles attached to a fan spraying mist on the participating students in a shaded-tree area [31]. ...
Article
Full-text available
Heat islands and warming temperatures are a growing global public health concern. Although cities are implementing cooling interventions, little is known about their efficacy. We conducted a literature review of field studies measuring the impact of urban cooling interventions, focusing on cooling centers, misting stations, cool pavements, and cool or green roofs. A total of 23 articles met the inclusion criteria. Studies of cooling centers measured the potential impact, based on evaluations of population proximity and heat-vulnerable populations. Reductions in temperature were reported for misting stations and cool pavements across a range of metrics. Misting station use was evaluated with temperature changes and user questionnaires. The benefits and disadvantages of each intervention are presented, and metrics for evaluating cooling interventions are compared. Gaps in the literature include a lack of measured impacts on personal thermal comfort, limited documentation on intervention costs, the need to standardize temperature metrics, and evaluation criteria.
... Mourot studied the limitation of maximal heart rate at altitudes frequently chosen for training (2000-3500 m), and the results confirmed the physiological and clinical effects of a hypoxic environment on exercise training [20]. Meanwhile, blood oxygen saturation and heart rate are often measured to determine people's adaptation at high altitude, and many studies have explored the relationship between thermal comfort and environmental or skin temperature [22][23][24][25][26][27][28]. The impact of the interaction between the barometric and ambient temperature on human comfort also needs to be clarified. ...
... Many previous studies have proven that skin temperature is remarkably constant and evidently related to human thermal sensation [22][23][24][25][26][27][28]. When the skin temperature rises to very high levels or falls to very low levels, the thermal sensation has a linear relationship with skin temperature [53]. ...
Article
An increasing number of people are living or working at high altitudes, which are often accompanied by cold environments. High altitude and cold exposure often result in physiological, perceptual and biochemical changes, thus affecting work efficiency and even human health. This study created different altitude conditions of 0 m, 2560 m, 3650 m, and 4290 m with an ambient temperature of -10 ℃ in a climate chamber. Six health subjects were recruited and human physiological and perceptual responses during this experiment were continuously investigated, involving objective parameters such as core temperature, local skin temperature, blood oxygen saturation, heart rate, respiratory rate and subjective parameters such as overall and local thermal sensation, overall and local thermal comfort. The statistical analysis showed that blood oxygen saturation is the most sensitive parameter to altitude changes, which is consistent with previous studies and shows a close relationship with altitude. All of the mean local skin temperatures in the face, hands and feet throughout the experimental period were lowest at 0 m altitude. The overall thermal sensation decreased by 2.83 units at 0 m, whereas it decreased by only 2.00 units at an altitude of 4290 m. The local thermal sensation correlated well with the local skin temperature (R² > 0.8) at 0 m, 2560 m and 3650 m. At an altitude of 4290 m, the local thermal sensations of the face, hands and feet were close to 0 (neutral). These findings indicate that higher altitude can compensate for some of the decreases in thermal sensation caused by a cold environment.
... The practical applications of water spraying are manifold. Some experimental studies have explored the impacts of simple mist-based cooling technologies on outdoor comfort, involving questionnaires on thermal comfort to supplement quantitative data on the levels of attainable comfort (Desert, Naboni & Garcia, 2020;Zheng et al., 2019). Additionally, water spraying is applied in pavement cooling (Parison et al., 2020;Wang, Meng et al., 2019) to mitigate UHI. ...
Article
Ethylene tetrafluoroethylene (ETFE) cushion roofs are used for improving indoor natural lighting. However, their poor thermal insulation compromises the indoor thermal environment. Water spraying offers promising potential in roof cooling, but its cooling and shading effects on ETFE cushion roofs have not been examined. This paper on roof-mount spraying systems aimed to address this gap with numerical simulation and a full-scale field experiment. Our findings indicated that exterior surface temperatures of ETFE cushion roofs should be kept below 33.7°C to establish a thermally tolerable indoor environment. Secondly, under limitations of field conditions, decreases in exterior and interior surface temperatures yielded by the spraying system respectively ranged from 4.8°C to 19.5°C and from 0.2°C to 4.9°C. Thirdly, the shading effects generated by spraying have been insignificant, with the average solar radiation shading rate being only 0.23. Lastly, decreases in temperatures for both exterior and interior roof surfaces could be expressed as a function of only four parameters with good accuracy (R² = 0.93 and 0.87, respectively). Decreases in exterior surface temperatures were most affected by exterior surface temperatures, followed by solar radiation, wind speed, and lastly the wet-bulb temperature, whereas decreases in interior surface temperatures were most affected by solar radiation.
Article
The spray system is widely used to improve outdoor thermal comfort, and choosing suitable spray flow is important for controlling the relative humidity and cooling air temperature. In this study, the spray cooling system of the outdoor traffic waiting area in Qingdao was used as the case study, and a traffic waiting area with three spray flow rates was established. Air temperature and relative humidity were monitored, and a questionnaire survey was conducted to collect indicators of the human thermal response. The results showed that at a flow rate of 30 ml/min, the spray system could effectively reduce the air temperature in the waiting area without increasing the human humidity obviously, thus improving human thermal comfort. At this flow rate, the predicted mean vote of thermal sensation improved from 2.06 ± 0.75(slightly above warm) to −0.42 ± 1.15 (between neutral and slightly cool), while the predicted mean vote of thermal comfort increased from −1.79 ± 0.94 (near uncomfortable) to 1.16 ± 1.43 (above slightly comfortable). And from the influence analysis of meteorological parameters on cooling efficiency, the high air temperature or high solar radiation increased the cooling efficiency of the spray system.
Article
The sustainable development and climate response have been paid attention to by many cities, especially under the high-temperature weather conditions in summer, which have caused huge environmental pressure on outdoor activities. The spray cooling system was the better choice to regulate the regional thermal environment in the outdoor high-temperature environment. This review focused on application efficiency, factors affecting cooling efficiency, optimization measures and future development of the spray cooling system, with the aims to provide a comprehensive and critical review of existing research and propose the future research trends. The results showed that the spray system could reduce the ambient temperature and improve the thermal comfort effectively, while the parameters of enhanced heat transfer were heavily discussed in the spray cooling system. The new thermal assessment models and extended parameters were also established to elevate the thermal comfort under the spraying environment. Finally, future directions were proposed on possible studies and applications.
Article
Full-text available
We explored the effects of mist spraying with different nozzle densities and heights on pedestrian thermal comfort during summer in Xi'an, China. Thermal perceptions of 106 college students in open spaces (sky view factors: 0.598–0.699) varying in nozzle density (4, 6 and 8 nozzles) and height (2.3, 2.7 and 3.1 m) in a 4.5 m² area were investigated using meteorological variables measured at 1.1 m above the ground and longitudinal questionnaire surveys. Universal Thermal Climate Index and skin temperature were selected to evaluate thermal perceptions and physiology. We found that: 1) Effects of mist spraying on humidification (2.60–7.03%), reducing globe temperature (6.55–15.15 °C) and mean radiant temperature (9.77–31.52 °C) increased as the nozzle number increased from 4 to 8. The effect of humidification declined as the nozzle height increased from 2.3 to 3.1 m (7.03–2.60%). 2) Subjects' thermal sensation vote decreased as the nozzle number increased from 4 to 8, and increased with nozzle height from 2.3 to 3.1 m. 3) ST reduction measured at the forehead (0.45–1.24 °C) and upper arm (0.38–0.95 °C) increased as the nozzle number increased from 4 to 8. Mean ST reduction decreased (0.72–0.53 °C) as the nozzle height increased from 2.3 to 3.1 m with 8 nozzles. 4) The UTCI reduction resulting from adding a nozzle was equivalent to lowering nozzle height by 0.82 m. A model of the nozzle density and height was built to predict when respondents would perceive neutral UTCI in misted environments.
Article
Full-text available
We recruited 72 healthy college students on a university campus in Xi'an, China to investigate the effectiveness of heat stress relief measures (shade, mist spraying and shade+mist) on enhancing outdoor thermal comfort. Using the Universal Thermal Climate Index (UTCI) and mean skin temperature (MST), we evaluated respondents’ thermal and physiological responses. We found that: 1) Mist spraying and shade were effective in improving respondents’ outdoor thermal comfort. The cooling effect of mist spraying was more effective than shade, while shade+mist provided a wider thermal comfort range. 2) UTCI declined among cooling strategies by 12.31°C (shade+mist), 8.03°C (mist spraying) and 3.48°C (shade) on average. 3) Shade and mist caused similar cooling effects on skin temperature (ST), but MST plateaued 5min after exposure to these cooling environments in isolation. Shade+mist provided the greatest cooling effect with MST continuing to drop as the exposure continued. 4) Predictive models showed that MST in shade, mist spraying and shade+mist decreased 0.24, 0.21 and 0.16°C, respectively when air temperature (Ta) declined 1°C with constant relative humidity (RH) and mean radiation temperature (Tmrt). MST in shade, mist spraying and shade+mist decreased 0.05, 0.08 and 0.06°C, respectively where RH increased 1% with constant Ta and Tmrt.
Article
Digital signage in public spaces is generally silent. However, the emission of sound with the aim of generating recallability produces noise, which can be uncomfortable for passersby in the surrounding space, resulting in a loss of acoustic comfort. In this paper, we implement an On-Demand pinpoint audio system in which sound is delivered only to one person, and only the sound of the advertisement that attracts the person’s attention is played. By applying this system to passersby, this paper examines the system’s influence on advertisement recallability and acoustic comfort. Additionally, we detect the categories of advertisements affecting the advertisement recallability and acoustic comfort when digital signs emit sound. Through experiments with 30 participants, acoustic comfort is maintained and On-Demand System can reduce noise level compared to loudspeaker. In addition, we collected participants’ self-reported recallabilities and analyzed by advertising category. These results show that music-dominating advertisements presented by the On-Demand System were more recallable than silent and other advertisement categories. These results indicate the possibility of personalization of the advertising information and the perceptual spaces, even if the individuals are in public spaces.
Article
In order to promote the redevelopment of cities in consideration of measures against extreme heat, the effectiveness of various heat mitigation technologies introduced by Kobe City was evaluated. We introduced each technology for heat countermeasures to the central part of Kobe city, clarified their effects by measurement, and discussed issues and evaluations for the implementation. Watering on road, sunshade with mist spray, water surface, watering on pavement, and mist spray in a park were introduced, and their effects were evaluated using the thermal environment index SET* based on the measurement results. Since it is necessary to compare and evaluate multiple technologies, the thermal environment index of the human body was adopted as a common index. The reduction in surface temperature, MRT and SET* by watering on the roadway were about 10 °C, 1.9 °C and 0.8 °C, respectively, and the effects lasted for at least 30 min. SET* was greatly decreased when the upper fractal sunshade blocked solar radiation to the central measurement point under the sunshade. The reduction of MRT and SET* on the watered on the pavement were larger than that on the water surface because the watered area was larger than the water surface area. MRT reduction due to wetting of the globe ball sensor by the mist spray had a greater effect on SET* reduction than air temperature reduction due to evaporation of the mist.
Book
Full-text available
Architectural design can no longer be only concerned with developing artefacts that produce reduced environmental impacts within a certain threshold of emissions. Conversely, buildings today must be developed to reverse the effects of climate change, increase the strength of natural systems and create a circular - carbon positive built environment that supports inhabitants wellbeing. “Regenerative Design in the Digital Practice” explores how the regenerative concept is now being applied to the design of cities and buildings. A series of digital design approaches are exemplified via a series of examples drawn from leading international practitioners and researchers from KADK, ETH Future Cities Laboratory, AIT Austrian Institute of Technology, TU München, Henning Larsen, BIG - Bjarke Ingels Group, Ladybug Tools, Living Future Institute, International WELL Building Institute - IWBI, EPFL, and many others. This book fills a gap in the existing literature by introducing fundamental design principles of regenerative design practice whilst outlining the potential and imperative of integrating science, big data and multi-discipline digital tools in the design process. The main editors and writers are Emanuele Naboni and Lisanne Havinga. The co-editors are Martin Brown, Angela Loder, Sergio Altomonte, Terri Peters, Luca Finocchiaro, Ata Chokhachian, Clarice Bleil De Souza, Catherine De Wolf, and Antonino Marvuglia. The preface is written by Maibritt Pedersen Zari. The book, published by Eurac Research, is open access thanks to the generous support of COST - European Cooperation in Science and Technology, the H2020 program and Cost Restore.
Article
Full-text available
For the first time, a systematic review was conducted on mist spraying systems used for outdoor cooling by perusing twenty years of publications from 12 countries and 7 climatic zones. The twofold aim was to emphasize both the potential against local overheating in a variety of climatic contexts and the extreme heterogeneity in terms of investigation techniques and performance metrics that hinder the construction of a cohesive body of knowledge. In addition to statistics and patterns, data were screened to outline theoretical and methodological trends and gaps and to detect geographic biases and climate dependencies. Indeed, each study was thoroughly described and comparatively discussed according to (i) the investigational method (purely experimental studies, purely numerical studies and those combining field tests with simulations), (ii) the results in terms of cooling, humidification and comfort, also in relation to the adopted performance metrics (iii) the design novelty. Most relevant approaches and findings were discussed and compared to identify governing variables, optimized configurations, unchartered solutions and criticalities. Overall, the collected data qualify water spraying as a cost-effective, versatile and high-impact blue mitigator. Opportunities and challenges towards an informed use emerged and will help delineating appropriate guidelines for practitioners involved in town development, to deliver strategies and precautions.
Article
Full-text available
Traditional methods to process comfort data are constantly criticised due to their inability to provide an explanation thermal satisfaction achievement. Theories, however, seem to present a solution to this growing issue. Therefore, this study aims to review how the efforts made in exiting literature to benefit from theoretical frameworks to understand comfort data. The results showed the usage of theories in outdoor thermal comfort research is extensively limited. Furthermore, from the three categories identified for classifying these theories (personal, environmental and behavioural) personal based frameworks are widely used. The results have shed light on our understanding of thermal satisfaction in outdoor spaces. It is expected the findings contribute to developing thermal comfort standards that are specific to outdoor setting.
Chapter
Full-text available
Landsat 8 satellite images will be collected to determine how urban heat islands have changed in Antofagasta during the period between June 2013 and March 2018. In this way its possible to determine whether or not there has been an increase in Surface temperaturas in the city and in different sectors that can mean heat sources within the city. The results obtained will be compared with records of atmospheric temperatures, where the values will be collected by data loggers, which are under the FONDECYT 1100657 project, which seeks to assess how climate change is affecting different urban centers in the country. With each one of these antecedents, it will be possible to verify the evolution that has manifested the temperature itself during the last 5 years, with the possibility of projecting the results to a future and to verify if the city can be affected by climate change.
Conference Paper
Full-text available
This draft paper was developed as a stalking horse for the Windsor 2014 Conference workshop on statistics, It presents the results of summer time field work undertaken by Abdulrahman Alsheikh in the region of Damman, Saudi Arabia and the data collected shows that middle-class homes families there occasionally report thermal neutrality at very high temperatures and humidities. The issues surrounding the collection, analysis, and understanding of the complex issues around the relationship between humidity and comfort at high temperatures has long been a difficult one and the paper sets out some general background, presents the preliminary findings from the Dammam field work and then raises some questions that we hope the expert statisticians running the workshop can help us make sense of, with a view to publishing a full paper subsequently including the results of the workshop deliberations.
Article
Full-text available
The principle of thermal alliesthesia indicates that the hedonic character of a thermal environment is determined as much by the general state of the subject as by the environment itself. An environmental stimulus that offsets or counters a thermoregulatory load error will be pleasantly perceived, and vice versa. Extant empirical evidence supporting thermal alliesthesia only exists for instances of core temperature deviation. Yet the reconciliation of alliesthesia with contemporary neurophysiological discourse (in the previous paper in this series) renders the concept directly relevant to everyday experiences in built environments where core temperature rarely deviates from neutral values. New experimental data are presented that explore alliesthesia in non-steady-state conditions across three different physiological states: thermoneutral; the upper and lower fringes of the thermoneutral zone; and mild excursions into the sweating and shivering regulatory zones. Thirteen human subjects evaluated the hedonic tone of a sequence of temperature step-changes and ramps. It was found that the psychophysiological principle of thermal alliesthesia operates within the thermoneutral zone, making it equally relevant to quotidian indoor environments as it is to the extremes found in traditional physiological research. Non-steady-state built environments can potentially offer spatial alliesthesia through carefully managed contrasts between local and mean skin temperature trends. Transitional zones are suggested as design solutions.
Chapter
Full-text available
The skin’s role in human thermoregulation and comfort E. A R E N S and H. Z H A N G, University of California, Berkeley, USA Introduction This chapter is intended to explain those aspects of human thermal physiology, heat and moisture transfer from the skin surface, and human thermal comfort, that could be useful for designing clothing and other types of skin covering. Humans maintain their core temperatures within a small range, between 36 and 38°C. The skin is the major organ that controls heat and moisture flow to and from the surrounding environment. The human environment occurs naturally across very wide range of temperatures (100 K) and water vapor pressures (4.7 kPa), and in addition to this, solar radiation may impose heat loads of as much as 0.8 kW per square meter of exposed skin surface. The skin exercises its control of heat and moisture across a 14-fold range of metabolisms, from a person’s basal metabolism (seated at rest) to a trained bicycle racer at maximum exertion. The skin also contains thermal sensors that participate in the thermoregulatory control, and that affect the person’s thermal sensation and comfort. The body’s heat exchange mechanisms include sensible heat transfer at the skin surface (via conduction, convection, and radiation (long-wave and short-wave)), latent heat transfer (via moisture evaporating and diffusing through the skin, and through sweat evaporation on the surface), and sensible plus latent exchange via respiration from the lungs. Dripping of liquid sweat from the body or discharge of bodily fluids cause relatively small amounts of heat exchange, but exposure to rain and other liquids in the environment can cause high rates of heat loss and gain. Clothing is used outside the skin to extend the body’s range of thermoregulatory control and reduce the metabolic cost of thermoregulation. It reduces sensible heat transfer, while in most cases permitting evaporated moisture (latent heat) to escape. Some clothing resists rain penetration, both to prevent the rain from directly cooling the skin, and to prevent the loss of insulation effectiveness within the clothing. Wet clothing will have a higher heat transfer than dry: depending on design, it can range from almost no From Thermal and Moisture Transport in Fibrous Materials, edited by N. Pan and P. Gibson, 2006, with kind permission of Woodhead Publishing Limited
Article
Full-text available
Providing thermally comfortable semi-outdoor and outdoor environments is essential to multi-functional public spaces such as museums, cultural centers and university campuses. Given the difficulty of controlling the thermal conditions, individuals may have reduced expectations regarding the thermal comfort of outdoor environments. An extensive field survey of five public places in Taiwan obtained 8077 sets of data. This study discussed thermal sensitivity and proposed thermal comfort ranges, neutral temperatures, and preferred temperatures for semi-outdoor and outdoor environments. The results show that occupants of semioutdoor and outdoor environments are more tolerant regarding thermal comfort than are occupants of indoor environments. Furthermore, global radiation appears to have greater potential to change subject thermal sensation than air movement. In a hothumid region such as Taiwan, semi-outdoor and outdoor environments, applied with sunshine eliminating design strategies, can effectively increase occupant thermal comfort.
Article
Full-text available
International standards that define thermal comfort in uniform environments are based on the steady-state heat balance equation that posits ‘neutrality’ as the optimal occupant comfort state for which environments are designed. But thermal perception is more than an outcome of a deterministic, steady-state heat balance. Thermal alliesthesia is a conceptual framework to understand the hedonics of a much larger spectrum of thermal environments than the more thoroughly researched concept of thermal neutrality. At its simplest, thermal alliesthesia states that the hedonic qualities of the thermal environment are determined as much by the general thermal state of the subject as by the environment itself. A peripheral thermal stimulus that offsets or counters a thermoregulatory load-error will be pleasantly perceived and vice versa, a stimulus that exacerbates thermoregulatory load-error will feel unpleasant. The present paper elaborates the thermophysiological hypothesis of alliesthesia with a particular focus on set-point control and the origins of thermoregulatory load-error signals, and then discusses them within the broader context of thermal pleasure. Alliesthesia provides an overarching framework within which diverse and previously disconnected findings of laboratory experiments, field studies and even comfort standards spanning the last 40 years of thermal comfort research can be more coherently understood.
Article
Full-text available
Evaporative spray cooling systems can be used to provide thermal relief on hot days, even in a subtropical climate such as in Japan. An experiment combining a water mist spray with a fan was conducted to cool an outdoor space and ascertain the comfort of 141 participants on hot summer days. Each participant was surveyed for ‘thermal sensation', ‘general comfort' and ‘feeling of wettedness' and skin temperature was measured before and after entering a mist. To characterize more directly the cooling effect of this particular mist system, a dry silicone rubber skin analogue including embedded heat flux sensors was heated to near-body temperature to measure the near-surface heat flux due to natural convection, forced convection by the fan alone, and the fan and mist together. It was found that the cooling effect of the mist and fan combination is highly efficient and easily exceeds the thermal load of pedestrians, yielding nearly instant decreases in skin temperature. Such outdoor technology has potential to reduce heat stress and discomfort, particularly at large outdoor events and festivals. It could also reduce the required cooling loads within individual buildings by providing inhabitants with thermal relief outdoors.
Conference Paper
Full-text available
Vertical cities growth is argument of discussion world-width. Population increases and a better soil use is needed, in terms of efficiency and density, in many cities of the world. However, an excessive vertical growth seems to be dangerous, especially near the green areas of midtowns. In this paper the case of Antofagasta is studied.
Article
Full-text available
Many new technologies and approaches to the provision of comfort inside buildings such as displacement ventilation, mixed-mode strategies, personally controllable (task-ambient) designs, chilled beams as well as some old but recently fashionable ones such as natural ventilation are prompting a rethink of the accepted comfort wisdom. How can a single combination of thermal environmental parameters be deemed unacceptable in a conventional heating ventilation and air-conditioning setting, and yet be regarded as acceptable, or even pleasant, in a naturally ventilated or mixed-mode setting? Why do current comfort standards prescribe static and isothermal conditions for comfort in one building, and dynamic and spatially variable indoor climates for comfort in another? The phenomenon of alliesthesia is used to differentiate thermal pleasure from thermal neutrality and acceptability. Alliesthesia is proposed as the logical framework of a new approach to thermal comfort modelling, building on the solid foundation of multi-node physiological models currently available in the literature. De nombreuses technologies et approches nouvelles visant à assurer le confort à l'intérieur des immeubles, telles que la ventilation par déplacement d'air, les stratégies à mode mixte, les conceptions à commandes individuelles (intégrant des luminaires autorisant un éclairage individualisé des différentes tâches), les poutres froides, ainsi que certaines technologies et approches anciennes, mais revenues en vogue, telles que la ventilation naturelle, amènent à repenser les idées reçues sur le confort. Comment une combinaison donnée de paramètres environnementaux thermiques peut-elle être considérée comme non acceptable dans un cadre à chauffage, ventilation et climatisation classiques, et néanmoins jugée comme acceptable, voire agréable, dans un cadre à ventilation naturelle ou à mode mixte ? Pourquoi les normes de confort actuelles prescrivent-elles des conditions statiques et isothermes pour assurer le confort dans un immeuble donné, et des climats intérieurs dynamiques et spatialement variables pour assurer le confort dans un autre ? Le phénomène d'alliesthésie est utilisé pour différencier le plaisir thermique de la neutralité thermique et de l'acceptabilité. L'alliesthésie est proposée comme cadre logique d'une nouvelle approche de la modélisation du confort thermique, s'appuyant sur les bases solides qu'offrent les modèles physiologiques multinodaux actuellement disponibles dans la littérature. Mots clés: acceptabilité alliesthésie asymétrie isotherme statique confort thermique perception thermique plaisir thermique thermorécepteur transitoire
Article
Full-text available
Direct evaporative cooling has long been recognized as an energy-efficient and cost-effective means for space conditioning in hot dry areas. In order to extend the use of evaporative cooling to include exterior or semi-enclosed spaces, a down-draft evaporative ‘cool tower’ was integrated in the project of a 500 m2 glazed courtyard located at the heart of a building complex in the arid Negev Highlands of southern Israel, designed by the authors. The present article describes the development of the cooling tower system, undertaken in three phases: (i) Prototype analysis. Performance of a small-scale tower was monitored, and comparisons were drawn between varying rates and mechanisms of water and air supply. The results indicated a potential for substantial temperature reduction in the order of 10 °C under summer daytime conditions, but a meager cooling output when using a natural draft system. Mechanical-forced air flow was thus utilized in the actual tower. (ii) Field monitoring. The cool tower, approximately 10 m in height and 10 m2 in cross-sectional area, was operated and monitored during a summer season; its performance was analyzed using a series of water supply mechanisms and operating modes. The system produced a peak cooling output of just over 100 kW, with a wet bulb temperature depression of close to 85–95% during all hours of operation, and a water consumption rate of approximately 1–2 m3/day. (iii) Refinement. Potential improvement in the system's operation was investigated through the development of a wind capture mechanism for increasing inlet pressure and air flow to the space. Both fixed and dynamic capture units were investigated, with wind speed and direction as well as internal air speeds measured in the small-scale prototype tower. The wind capture unit with the simplest configuration and best performance is recommended for future integration in the full-scale tower.
Article
Full-text available
Field studies conducted in tropical climates have found that the International standard for indoor climate, ISO7730 based on Fanger’s predicted mean vote (PMV/PPD) equations, does not adequately describe comfortable conditions. This paper presents some of the evidence and suggests ways in which International standards are failing and how they might be complemented using adaptive comfort standards derived from the results of local comfort surveys. In particular the implications of air movement and humidity for adaptive comfort standards are considered.
Preprint
This paper reviews frequently used outdoor thermal comfort indices in hot-humid regions and neutral thermal ranges to offer guidelines for selecting an appropriate index for hot-humid regions. An overview of the development of outdoor thermal comfort (OTC) indices based on type of approach, from linear equation approach-to adaptive thermal comfort model-is provided and the advantages and limitations of each index are presented. Subjective neutral ranges from 31 studies conducted in hot-humid regions were assessed on the basis of geographical location, Köppen-Geiger's climate classification, parameters, a survey method, instrumentation setup , respondent profile, method of analysis, neutral range, and coefficient of determinations in order to gain an understanding of their deviations. The review of 31 calibration studies of (m)PET's, (OUT_)SET*'s and UTCI's neutral ranges indicated that the lower threshold of (m)PET's neutral range needs to be lowered, while the lower threshold of (OUT_)SET*'s and UTCI's ranges should be raised. The appropriateness of (OUT_)SET*'s thermal range for hot climates was proven by its full-coverage neutral range in the evaluation. However, the accurate response to ambient thermal conditions was determined by the advancement of a human thermoregulatory model.
Article
This study aimed to evaluate an outdoor mist-spraying environment and its effect on thermal sensations, thermal environment, and skin temperature. A mist-spraying system with four modes was operated with various amounts of water spraying, both in the absence and presence of an air blowing control. Thermal sensations were reported by subjects for each operation mode and then investigated using three scales: modified thermal sensation vote (mTSV), thermal sensation vote (TSV), and comfort sensation vote (CSV). Environmental factors were compared between the outdoor and mist-spraying environments, and skin temperatures were monitored throughout the experiment. The correlation between the thermal sensations and overall skin temperatures was analyzed. The results showed that the air temperature inside the mist-spraying environment decreased (−2.9 ± 1.2 °C) when the mist system was operated with a larger amount of spraying water and the air temperature decreased further (−3.6 ± 1.4 °C) with the addition of an air blowing fan. Survey results (n = 65) suggested that the mTSV changed from slightly hot to neutral, TSV changed from warm to neutral, and CSV changed from slightly uncomfortable to slightly comfort, respectively, due to the cooling effect of the mist-spraying system. The overall skin temperature decreased by approximately −0.53 °C (n = 65) from the baseline operation mode. Moreover, the overall skin temperature showed a higher correlation with the mTSV than with the TSV, and their correlation was higher in the mist-spraying environment compared with that in an outdoor environment.
Article
The study of thermal comfort in Latin American cities has been gaining great relevance for urban environmental planning. Some studies have evaluated the relationship between environmental and perceived comfort; however, the causes and social determinants of the different perceptions of the population have not been explored. The perception of thermal comfort in public spaces in the city of Chillán (Chile), which has an inland Mediterranean climate, is discussed in this context. First, we measured the environmental thermal comfort, adapting the Actual Sensation Vote index. A survey of 362 users of the five selected public spaces was carried out between 29 January and 01 February 2016 to obtain perceived comfort and relate it to the individual climatic history, use of public space and place of residence in the city. The results show that perceived thermal discomfort dominates over comfort on summer days; however, those users who visit public spaces for recreational purposes feel more comfortable, as well as those living in low socioeconomic status (SES) neighborhoods. On the other hand, users living in areas with higher socioeconomic status, have higher expectations regarding thermal environmental conditions.
Article
Tropical countries, like Singapore, are hot and humid throughout the year. Coupled with the Urban Heat Island effect from rapid urbanisation, Singapore has seen a long-term increase in annual average temperatures over the years. One solution is the use of misting systems that tap on the principle of latent heat of vaporisation to provide cooling. This paper specifically addresses the use of air-assisted "Dry Mist" systems, where the sprays are of ultra-fine droplet size, measured using PIV system in this study, and do not cause a wet sensation upon contact. This study has found that suitable operation conditions are during hot afternoons where Relative Humidity is lower, between 50–65%. Through both objective and subjective measurements, it was found that wind velocities above 0.58 m/s and Solar Irradiances above 571 W/m² are the limits for operation. The subjective measurements also found majority of the participants feeling colder from the system, and despite a slight increase in skin wetness, there is also increase in wet feeling pleasantness. A statistical analysis also found that changes in Thermal Sensation Vote (TSV) is most significantly captured by changes in skin temperatures and wet feeling pleasantness vote, while changes in Thermal Comfort Vote (TCV) is most significantly captured by changes in Tmrt and Air Humidity Vote.
Article
The present study assessed a new index that can evaluate thermal sensations in outdoor and mist spraying environments. Mist spraying systems have been widely used to relieve thermal discomfort in hot weather. However, relatively few studies have investigated the environmental indices to evaluate thermal sensations in mist spraying environments. Therefore, this study carried out experiments to collect data for the environmental factors, physiological responses, and survey results in a mist spraying environment. In the first experiment, subjective assessments and environmental factors measurements were conducted. Based on the experimental analysis, the conventional indices were examined to determine the acceptability in the mist environment. In the second experiment, the thermal state of the subjects was estimated using Gagge's two-node model with the measured environmental conditions. The validity of the prediction model was confirmed by comparison with the measured subject's physiological responses. The results showed that the conventional SET*, PET, WBGT, and UTCI indices could not fully represent the thermal sensation and comfort in the mist spraying environment, while the two-node model showed accurate prediction results for skin temperature. In conclusion, a concept of new index to assess the thermal sensation of the outdoor and mist spraying environment was proposed by comparing the predicted thermal state of the body and the subjects mTSV (modified thermal sensation vote). The proposed index is expected to estimate the thermal sensation inside and outside of the mist spraying environment only using measured environmental factors.
Chapter
Hard urban surfaces (concrete and asphalt) absorb solar radiation and re-radiate it as heat; and industry, transport and air-conditioning release waste heat to atmosphere. This urban heat island (UHI) effect is the most documented phenomenon of climate change. The interaction between global climate change and the local UHI is creating unprecedented challenges to human health, wellbeing and development. Most twenty-first century populations live in cities, so mitigation of urban overheating is an increasing priority. This century has seen the development of important mitigation technologies, ranging from interactive water features to urban greening and high-tech materials. A variety of mitigation solutions are required to address urban heat across diverse climatic contexts. This chapter explores some of this research, and highlights positive progress which offers grounds for optimism.
Article
An experimental study was conducted to improve the comfort and liveability of urban open spaces during the hottest months of the summer by implementing an overhead water mist cooling system. The campaign was conducted in two different Italian urbanscapes (Ancona and Rome, representative of Cfa and Csa climates) one after the other. Monitoring data and comfort questionnaires were combined to extract useful information by means of statistical tests, regressions and data mining algorithms and, ultimately, to delineate design and operating guidelines to maximize people's satisfaction with the misted environment. The cloud of droplets reduced the temperature and the UTCI by 8.2 °C and 7.9 °C respectively, against a 7% mean humidity premium. The vertical cooling and humidification profiles obeyed a Lorentzian distribution, peaking within approximately 0.5 m of the injection. The severe overheating experienced outside of the cooled areas evanished under the spray, with 67% (Ancona) to 90.6% (Rome) of respondents reporting only slight bending from thermal neutrality. Perception and preferences towards solar radiation, humidity level and wind all improved within the droplets mist. In terms of comfort-oriented, optimized design criteria, the system proved to work best with a dominant and steady light breeze (1–2 m/s), in highly irradiated sites and suspended at 1.2–1.5 m above the average height of users.
Article
Comfortable and healthy outdoor microclimates are beneficial to sustainable urban development. Based on a comprehensive comparison of some currently frequently used thermal comfort indices, including PMV, WBGT, PET, SET*, and UTCI, the differences among these indices are significant in dealing with the fundamental energy balance model, descriptive equations, and application boundary conditions. In order to validate these indices, a subjective questionnaire survey with field measurements was carried out on a university campus in Guangzhou in southern China. Results revealed strong linear relationships between operative temperature and mean radiant temperature (Tmrt), WBGT, PET, SET*, UTCI, as well as PMV. However, the relationships between these thermal comfort indices and the mean thermal sensation vote (MTSV) are not clear for a hot outdoor environment, especially when the operative temperature was above 34 °C. The ranges of the heat stress category and PMV need to be modified for the evaluation of hot outdoor environments.
Article
Maximising outdoor space usage in hot weather in summer is conducive to energy saving as indoor cooling demand can be reduced. Understanding the subjective thermal perception is essential for landscape designers to optimise the thermal quality of outdoor spaces. A combined meteorological measurement and questionnaire survey was conducted in Hong Kong's summer. 427 valid questionnaires were collected. The 80% acceptable temperature ranges in PET and UTCI were 21.3 to 39.5 °C and 22.7 to 38.8 °C respectively. The questionnaire data showed that 35.6% of the respondents found it unacceptable to stay at the interview site for an extra one hour although only 9.1% of them felt unacceptable during the interview. A new benchmark range – 1-h 80% acceptable temperature range – is therefore proposed to assess the usability of outdoor space in the longer term. The proposed benchmark reduced the acceptable ranges to 21.3 to 27.3 °C and 22.7 to 30.4 °C in PET and UTCI respectively. The attendance of an exposed site was found to be a half of a tree-shaded site due to the shorter thermally acceptable time. Optimal wind speed was found to be 2.7 m/s, which is higher than the previously suggested range (1.0 to 2.0 m/s).
Article
Cities are dissipative structures. As such, cities generate heat, a phenomenon known as urban heat island (UHI). Even though the UHI is one of the most relevant effects of urbanization on urban climate, up-to-date methodologies to include it in the estimation of buildings’ energy consumption are still scarce. During the last 30 years, different methods and software have been developed to measure a thermal building's demand. Building performance simulation is commonly used to calculate heating and cooling demand. However, such techniques do not adequately include the urban heat island effect, which could have an extreme impact on a building's energy consumption. In fact, building operation is doubly connected with the urban environment: on the one hand, buildings generate heat that warms up the environment, and on the other hand, the urban environment alters building performance by the influence of UHI. In this paper, a methodology to incorporate the UHI effect in building performance simulation is proposed. Urban weather data were downscaled at the urban morphology building level to estimate the cooling demand of different types of residential buildings. The global energy penalty for the whole residential building stock was estimated in four South American Pacific coastal cities. The results indicate that when UHI is incorporated, an increase in energy demand between 15% and 200% can be expected. These results challenge the validity of current assessments performed in absence of the UHI effect. At the same time, these results open up the discussion for the inclusion of urban planning measures aiming at reducing the UHI effect on a building's energy demand. Link: https://authors.elsevier.com/a/1UtXE1M7zGsh4p
Article
This paper aims to bridge the gap between urban climatology and urban design in coastal temperate climate cities of developing countries. This research studies the thermal comfort in urban canyons located in the city of Concepción, Chile, using a multidisciplinary approach that combines morphological, climatic and perceptual factors. First, the urban morphology indicators are constructed, such as the sky view factor and the shadow factor of buildings. Second, to determine the environmental thermal comfort, the Actual Sensation Vote (ASV) method is used by conducting measurements in 27 control points in 9 urban canyons. Third, 301 surveys were conducted to pedestrians in urban canyons during January 2014. All the data is processed and correlated to determine how the urban canyons morphology modifies the dominant climate in terms of physical and perceived thermal comfort. The results show that the diagonal canyon has one of the best indicators of environmental and perceived thermal comfort. On the other hand, the semi-covered canyon with high pedestrian affluence has the worst comfort values. Overall, the metropolitan center of Concepción is more comfortable than uncomfortable in the summer season.
Article
Outdoor human comfort is an essential parameter to assess the quality of the urban microclimate, and to provide guidelines for sustainable urban development. This paper presents a comprehensive review of available tools for modelling outdoor human comfort and thermal stress, explains the physical equations that drive these models, and shows their applicability based on climate and the findings of previous research. The existing procedures are subdivided into three main categories: Thermal indices, Empirical indices and indices based on Linear Equations; for each approach, case studies are presented and subdivided according to Koeppen Climatic Classification (Polar, Cold, Temperate, Arid and Tropical). International regulations and software available to quantify outdoor human comfort and microclimate are presented, as well as a graphic thermal scale to compare the ability of each procedure to respond to the 11-point thermal sensation scale (from Sweltering to Extremely Cold). Finally, the models are presented as function of their ability to analyse climate, microclimate and human-related characteristics of the selected built environment. This paper aims at bringing a comprehensive introduction to the topic of the outdoor human comfort, helping the reader to understand the existing procedures and guiding the choice of the suitable options according to specific research needs.
Article
Experimental data from five previous comfort studies are used to derive formulas for the thermal sensation of sedentary and near-sedentary residents, and to examine the effect of one variable, humidity, on the perceived levels of comfort. Studies in Thailand, Singapore and Indonesia (two studies) investigated indoor comfort, and a further study in Japan investigated outdoor comfort. Thermal sensations of human subjects were recorded under different conditions of temperature, air speed and humidity. In the outdoor study in Japan, solar radiation and surrounding surfaces temperature were also measured. All these studies found that the effect of humidity, expressed as the humidity ratio (gr/kg) on the thermal sensations of sedentary and near-sedentary resident persons tested, was very small to negligible, suggesting an insensitivity of the (acclimatized) subjects to the humidity level within the range encountered in the countries where the studies were conducted.
Article
A simple theoretical analysis of heat-and-mass transfer to a spherical water-droplet moving in humid air has been made, in connection with the possible use of spray or mist cooling in railway tunnels and other systems. In particular, the histories of the temperature and diameter of the droplet, and the dependence of the time of complete evaporation (or life-time) on the initial size have been studied. The relationships between life-time and the maximum time the droplet may be air borne in the particular environment, (such as a tunnel), has been investigated using the settling time of a freely-falling droplet as a basis of measurement.
Article
Recommendations for indoor thermal requirements have been based upon verbalized responses on traditional assumptions that (1) minimal thermoregulatory activity may be equated to maximum subjective acceptability (2) sensations and levels of discomfort are synonymous and (3) perception of warmth is exclusively the function of thermal stimulus — physiological response. These concepts are reviewed in the light of recent researches which indicate the inadequacy of the existing physiological models and methods of research. In particular, recognition is made of higher levels of mental integration of information flows which, it is argued, must include parameters of past cultural and climatic experiences and expectations. The aim is to initiate a more holistic approach to research into human thermal environments, and, a clearer definition of concepts significant to practical application.
Turn Off the Sunshine': why shade is a mark of privilege in Los Angeles
  • Tim Arango
  • Bethany Mollenkof
Humid Climates, SpringerLink
  • James A Henry
Heat: the next Big Inequality Issue, The Guardian. Guardian News and Media
  • Amy Fleming
  • Ruth Michaelson
  • Oliver Holmes
  • Adham Youssef
Quantifying the Over-estimation of the Perceived Cooling from a Mist Fan
  • Farnham Craig
The simulation of mean radiant temperature in outdoor conditions: a review of architectural tools calculation assumptions
  • E Naboni
  • M Meloni
  • C Mackey
  • J Kaempf
Trapping Humidity out of Fog in Chile
  • Fellipe Abreu
  • Felipe Luiz
  • Silva
Ladybug Tools | Outdoor comfort tools
  • Chris Mostapha Sadeghipour Roudsari
  • Ladybug Mackey
  • Tools
Puerto De Antofagasta: Un Dispositivo Urbano Que Intoxica
  • Francisco Perucich
  • Alberto Vergara
  • Mejía