Due to the increasing rate of urbanisation and population, the consequences resulting from heat impacts should be vital in order to obtain sustainable living. Climate change on outdoorthermal environment and UHI dominantly effect human health and well-being in a city. The increment in outdoor air temperatures also creates economic consequence, where UHI has clearly exemplified the environmental and economic impacts associated with a rise of ambient temperature. Apart from that, climate effects are negatively impacted by the UHI phenomenon, especially for people working outdoors. The outdoor environment is the most extreme and critical condition in investigating humanthermalcomfort as it is exposed to the "double sun" phenomena, exposure from both direct sunlight and heat reflecting off the surrounding buildings. These issues can lead to social impacts if there is still lack of awareness and attention given to the thermal condition. The current study focused on the determination of thermalcomfort in selected areas, with several urban environmental parameters, i.e. street geometry, orientation, surface albedo and vegetation, and concentrated on using conventional methods for accessing heat stress. However, a knowledge gap still exists, which can be related to the impacts of thermalbehaviour on outdoorhumanthermalcomfort and heat stress in tropicalclimate, in terms of the effect of the built environment, land use and artificial construction materials. Little research can be found on the relationship between the impact of urban surface thermalbehaviour and outdoorthermalcomfort in Johor Bahru a city in Malaysia.
One of the very few studies on the urban street microclimate which focuses on radiation fluxes confirms the advantage of shading towards a reduction of the radiant heat gained from a human body when compared to a person standing in a fully exposed location .Trees as shading elements are very important to urban design. One important impact of street trees on citizens is the reduction of thermal stress during hot meteorological background conditions . There are a few studies on the effect of planting trees on improvement of urban areas especially streets according to thermalcomfort. While green cover is one of the most important solutions for creating appropriate micro–climate in harsh climates, especially in hot & dry climates and increase in their seeding is one of the best option to higher the pedestrian comfort level. Street trees will be most effective in providing “true” shade. Trees should be located to maximize shade for pedestrians, such as along walkways and sidewalks. Tree can improve the ambient air temperature by up to 15 % . Studies show that individual trees in high distances will have a little impact on comfort and cooling. Therefore, it has been recommended that it is more effective for urban sites to use several smaller groups of trees .
habitable outdoor spaces so that they improve the outdoor activities. User experience of space is greatly affected by the thermalcomfort level of that space. Metropolitan cities and city squares are facing challenges of increased heat at microclimatic scale. Cities are facing challenges to mitigate the environmental impact due increased surface area of buildings .Due to thermal discomfort people have declined the use of public open spaces. Lots of public spaces became dead spaces during the daytime. Merely because there are not habitable. Which creates cultural gap due to lack of interaction between people in outdoor areas which also affect the neighborhood livability, street life, outdoor activities etc. The professionals such as Architects, landscape architects, urban designers should intervene in these situations to make cities habitable to live. Innovative approaches to urban open spaces will become more important as the Indian population is becoming more urban. Research and solutions are focused mainly on the pollution, greenhouse gases, burning of fossil fuels for urban climate change, whereas the whole surface area of a building contributes to the heat emission in higher quantity. Design of vertical surfaces will show designers how to work to create climatically habitable spaces for human activities. With remarkable clarity, it covers both the scientific background and the design techniques needed for shaping spaces that increase comfort and reduce energy consumption.
DOI: 10.4236/acs.2019.94036 559 Atmospheric and Climate Sciences high levels of heat stress, extended exposure to extreme levels of cold stress can impacthuman health, reduce the efficiency of performed activities, lead to frost bite, hypothermia or even death when the exposure impairs thermoregulation     . Cold stress is a significant risk factor among patients, particu- larly women with cardiovascular diseases . Unlike heat waves, during which mortality raises for several days, cold spells may increase levels of mortality for several weeks . Thus, as more people visit, work and/or live in Alaska and its off-shore areas, adequate public health system and urban planning require as- sessment of the outdoorthermal environmental conditions in form of climatol- ogy and frequency of occurrence at high spatial resolution.
as such data were not available for the investigated area; the meteorological file of Lagos, the neighbor Nigerian town was taken into account. This town is less than 100 km from Cotonou and has almost the same climate as the coastal strip of Benin. Fig. 4 (a) shows the annual change in air temperature. It is observed that temperatures between 24 and 34˚C are the most frequent in this region. Temperature is above 30˚C in the hottest months. It reaches its highest value in January, March and October, and the lowest one in December, July or August. Fig. 4 (b). displays the monthly change in March outdoor air temperature. Fig. 5 (a) shows the change in relative humidity throughout the year. The lowest values for relative humidity are between November and March, mid-July and mid-September. This happens in the dry season. But the highest values appear between April and July, mid-September to October with a peak in August during rainy seasons when they exceed 90%. But overall, the humidity of the air remains higher than 50% throughout the year. Fig. 5(b) presents the monthly change in the relative humidity of outside air in March. Fig. 6 (a) displays the change in global radiation, normal direct, diffuse radiation over the year, and Fig. 6 (b) zooms in during the first week of January.
This paper reviewed the impact of different heat mitigation strategies on the pedestrians’ thermalcomfort in the context of urban and microclimate. It should be noted that the magnitude of UHI varies in different climates. Consequently, in each climate, a specific heat mitigation strategy is needed. Most of the previous studies have investigated the changes of meteorological variables (such as air temperature deviations) by heat mitigation strategies. Among different heat mitigation strategies, vegetation and high albedo (reflective) surfaces as solutions for improving outdoorthermalcomfort in urban spaces were investigated in this paper. Vegetation was studied in the forms of parks, street trees, green roofs and green walls. High albedo materials were then studied while they are used on the roofs (as white roofs) and on the ground surfaces. Through several examples in different countries and climates, it was shown that urban surfaces play an important role on the thermalcomfort of pedestrians. Vegetation and high albedo surfaces showed appreciable reduction of air temperatures within urban open spaces. However, mean radiant temperature affects humanthermalcomfort more than the other
Fig. 1. Location of Iraq and the neighbouring countries . Regarding the investigation study conducted in Iran (Tehran city) on the strategies to reduce the impact of Urban Heat Island on the human health , the results showed that the amount of vegetation placed on a building and its position (roofs, walls or both) is a more dominant factor than the orientation of the urban canyon. The canyon geometry with green roofs and walls that had a low thermalimpact could play a more important role than the street orientation. Also, the study revealed that the heat sensation zones “hot” and “warm” are not achieved when urban roofs and walls are covered with vegetation, leading to more pleasant and comfort environments for the city residents. An investigation study was conducted of the warm core of Urban Heat Island in the highland zone of Muscat, Oman . The valley is surrounded by mountains formed of dark colored rocks that can absorb the short wave radiation and contribute to the existence of the warmth in the core of the urban area. The study emphasized the importance of the nature of rural baseline when assessing the urban effect on an urban area climate. A study was conducted in Bahrain City  to analyze the impact of the urbanization on the thermalbehaviour of newly built environments. The results revealed that the recent process of the urbanization leads to an increase in the urban temperature by 2-5 ℃. The increase in temperature is enhanced by the urban activity such as on- going construction processes, shrinkage of green areas and the sea reclamation. Several studies indicate how the green effects have a crucial role in the process of sustainable cooling of the urban planning and in saving energy and
Figure 14. Average of total cooling energy (Kw) in model rooms in different models
In this study, environmental conditions of the passive rooms are only considered. Corner zones have been omitted because they are exposed to environmental variables from different orientations. Otherwise, the impact of a single orientation cannot be clearly understood. Non-passive rooms have also been excluded, because in the tropical hot-humid climate they are considered to become overheated even when outdoorthermal conditions are acceptable. Excluding the corner and non- passive zones, average cooling energy demand in all passive rooms in Model 1 is found to be the lowest (Figure 14). Although solar gain in Model 1 (0.2885 kW) is almost equal to solar gain in Model 2 (0.290175 kW), its cooling load is lowest due to the fact that much of its heat is carried away (through internal conduction loss) to the neighbouring non- passive rooms which are protected from direct solar gain (solar heat gain is zero) (Figure 15). Again in Figure 14, energy performance of Model 2, enclosed courtyard is the poorest. Apparently, this has resulted from higher average solar gain, external conduction gain and lower Macroflo internal ventilation loss in Model 2 (Figure 15). Although Model 2 and Model 3 have similar courtyard sizes and Model 2 has higher site coverage (64%) than Model 3, the former is vulnerable to more solar radiation (and thereby higher external conduction gain) due to its lower height. This indicates shallow courtyards may not be proper for this climate to protect from solar gain. Comparison of solar radiation for Model 3 (8 storied) and Model 4(7 Storied) reveals the same fact as solar Figure 15. Sensible heat balance in different models
‘adaptive behaviour’ and ‘weather opinion’. Personal informa- tion of the respondents, such as gender, age, body type, activity, exposure to direct sunlight and clothing level were also included in the table. These were determined by observation during the survey. Several personal characteristics were noted by directly asking the respondents about their residence status in the city, nature of their profession, interviewees’ sweat-levels (Ng & Cheng 2012 ), exposure to air-conditioned space and travelling situations in the last 30 min, etc. Profession is grouped as Bindoor type^, who work in an indoors environment and Boutdoor type^, who work mostly outdoors (e.g. street traders) (Ahmed 2003 ). Respondents’ psychological factors included visiting purposes to the site and whether the next destination is air conditioned or not. Choice of adaptive behaviour, consump- tion of hot food or cold drinks, etc. were considered under ‘adaptive behaviour’. Additionally, interviewees’ judgement of the prevailing humidity, wind speed and solar radiation condi- tions during the survey were recorded. The reason for consider- ing the ‘visiting purpose’ and ‘next destination is air condi- tioned’ under the psychological category is that both have con- siderable psychological impact on the respondent’s mental situ- ation. Visiting a place for leisure could have a different psycho- logical effect to someone who is present for work. Pantavou and Lykoudis ( 2014 ) and Pantavou et al. ( 2013 ) have shown in their studies that people visiting the site for work felt cooler than those visiting the site for rest, due to both psychological effects and also because the former group had better adaptation due to lon- ger exposure time than those simply passing by. Similarly, peo- ple whose next destination is air-conditioned could be more tolerant to warm situations as they know any discomfort is tem- porary. Regarding ‘weather opinion’, although Pantavou et al. ( 2013 ) have discussed this under psychological parameters, it is discussed separately in this study as these can be broadly treated as comparable to the ASHRAE TSV. This is similarly applicable in the case of adaptive behaviour.
When designing sustainable green space, addressing outdoorthermalcomfort and heat stress have become more a prevalent focus. Therefore, the physiological and psychological impact should have been taken into account when designing green spaces. Previous studies described thermalcomfort as a fundamental parameter, as well as how heat stress/thermal discomfort affects these outdoor activities (Knez et al., 2009; Nikolopoulou & Steemers, 2003; Vanos et al., 2010). These studies explained the consequences, implication and outcomes of how heat stress affected human life. Givoni et al.(2003)mentioned while staying outdoors, people should have various unlimited condition like the sun and shade, changes in wind speed, and so on. Moreover, some studies stated the need of shades as an important element for outdoor spaces (Akbari et al., 2001; Hwang et al., 2010). Comparisons between demography were also studied; between the age group(Kenny et al., 2010), gender (Gagnon et al., 2009), clothing type (Davis et al., 2011; Gavin, 2003; Havenith, 1999) and area of living in thermalcomfort studies worldwide (Thorsson et al., 2007). However, studies on heat stress in tropical countries are still inadequate (Djongyang et al., 2010).
It is acknowledged that the transfer of climatic knowl- edge into planning practice is still lacking [1, 2]. Although many measures to reduce urban heat stress and/or improve outdoorthermalcomfort have been proposed by various researchers and at diﬀerent spatial scales [2–6], their ef- fectiveness is a subject for debate. The main reason is that the dominant professions for urban design and planning, namely, architecture and engineering, so far focus on the inﬂuence of landscaping on air and surface temperatures and their subsequent eﬀect on buildings . However, the im- pact of countermeasures by urban design on urban thermalcomfort cannot be described suﬃciently by simple micro- climate factors, such as surface or air temperature. There are seven factors (or parameters) that aﬀect humanthermalcomfort in an outdoor environment. They are air temper- ature, air humidity, wind, solar radiation, terrestrial radia- tion, metabolic heat, and clothing insulation . The ﬁrst
Received: 6 December 2017 / Revised: 13 July 2018 / Accepted: 25 August 2018 # The Author(s) 2018
A thermalcomfort questionnaire survey was carried out in the high-density, tropical city Dhaka. Comfort responses from over 1300 subjects were collected at six different sites, alongside meteorological parameters. The effect of personal and psychological parameters was examined in order to develop predictive models. Personal parameters included gender, age, activity, profession- type (indoor or outdoor-based), exposure to air-conditioned space and sweat-levels. Psychological parameters, such as ‘the reason for visiting the place’ and ‘next destination is air-conditioned’, had statistically significant effects on thermal sensation. Other parameters, such as ‘body type’, ‘body exposure to sun’, ‘time living in Dhaka’, ‘travelling in last_30 min’, and ‘hot food’ did not have any significant impact. Respondents ’ humidity, wind speed and solar radiation sensation had profound impacts and people were found willing to adjust to the thermal situations with adaptive behaviour. Based on actual sensation votes from the survey, empirical models are developed to predict outdoorthermal sensation in the case study areas. Ordinal linear regression techniques are applied for predicting thermal sensation by considering meteorological and personal conditions of the field survey. The inclusion of personal and weather opinion factors produced an improvement in models based on meteorological factors. The models were compared with the actual thermal sensation using the cross-tabulation technique. The predictivity of the three models (meteorological, thermos-physiological and combined parameter) as expressed by the gamma coefficient were 0.575, 0.636 and 0.727, respectively. In all three models, better predictability was observed in the ‘Slightly Warm’ (71% in meteoro- logical model) and ‘Hot’ (64.9% in combined parameter model) categories—the most important ones in a hot-humid climate. Keywords Outdoorthermalcomfort . Questionnaire survey . Thermal sensation vote (TSV) . Predictive model . Tropicalclimate
odel formulation for quantifying thermalcomfort perception is, generally based on empirical approaches from laboratory studies on the subject (human) in an activity and obtain certain climatic conditions. It was during the last decades developed by experimentation in the rooms (indoor spaces), which became the subject of research aimed to develop and establishing criteria for technology and design of indoor spaces (architecture). The principal orientation of thermalcomfort criteria is for standardization of buildings types and equipment that are energy efficient and environmentally friendly. Fanger's work  which produced the PMV, that is a scale of humanthermalcomfort inside a closed room, still used as reference by many authors. But in this case the problem of climate that occur in outdoor space may be different from the situation of an indoor space. The perception level of comfort by the human being in indoor space would be different if people are in the outdoor.
Outdoorthermalcomfort in urban environments is a complex issue involving many affecting aspects. Environmental stimulus (e.g., the local microclimatic condition) is the most influential factor on the thermal sensation and individual convenience level. Thermalcomfort is not only determined by the physical state but also by the state of mind. Hence, the assessment to describe the public perception of thermalcomfort must work on at least four levels: physical, physiological, psychological, and social/behavioural extents. The perception begins to form when the environmental sensing process occurs. Concerning thermalcomfort, the sensing starts with the presence of physical stimuli which are then perceived by individuals with their own distinct characteristics. Those individual characteristics include the ability or level of adaptation, psychological control, personal factors related to social connections with the community, and prolonged exposure to the stimulus. This adaptability can bridge the four aspects through the physiological thermoregulation with thermal neutrality as the adaptation process. The assessment of thermalcomfort is dynamic and subjective: dynamic in the sense that the adjustment to the ambient thermal condition is naturally progressive, also subjective given that the thermal sensation is primarily determined by personal experiences and subjective evaluation that thermalcomfort does not always refer to climatic conditions. In other words, the static and objective aspects (i.e., physical and physiological characteristics) should be measured to provide “knowledge on climate” through an effective model, while the dynamic and subjective aspects (i.e., psychological and social/behavioural characteristics) require a comprehensive interview and observation to provide “knowledge on human”.
Currently energy performance predictions are based on climate data of the recent past, for example typical meteorological year data (TMY3). Typical climate conditions for the 20 th century may not provide the full range of extreme conditions that will be encountered by the built environment of the 21 st century and thus there is growing interest in understanding the impact of future climate models on energy performance predictions for risk management. In previous studies Huang (2006) (as reported by Xu et al., 2009) used results of four global climate model (GCM) future climate scenarios to estimate that net energy use by residential and commercial buildings in Los Angeles will increase by 25 - 28% by 2100 due to increase in atmospheric greenhouse gases. Crawley (2008) used GCMs with statistical downscaling to represent four scenarios of climate change and two cases of urban heat islands for 25 locations worldwide. Overall, the impacts of climate change were projected to reduce energy use for cold climates by around 10% and to increase energy use in tropical climates by more than 20%. In mid-latitudes energy use would change from heating to cooling. The study states that unless significant changes are made to buildings and how they are designed, “building owners will experience substantial operating cost increases and possible disruptions in an already strained energy supply system.”
The thermoregulatory influence of building materials to improve the thermalcomfort of buildings has been examined primarily using climate modelling based on the work of Fanger (1972). This modelling has limitations because it does not accept that building occupants are active participants in controlling their thermal environment. This thesis addresses this knowledge gap by examining how thermalcomfort in the temperate climate of Hobart, Tasmania, Australia is influenced by thermal mass in buildings. This research assessed: how the temperate climate of Hobart impacts the thermal environment of a building; how past research in passive design for energy efficiency has been adopted, and; what methods of modelling and studying thermalcomfort are appropriate. The nine case studies examined a range of building and occupant types. An analysis was undertaken for each building including zoning and layout, building materials and insulation. Occupants were interviewed at the commencement of each case study which included examining acclimatisation to the local climate and thermal satisfaction with the dwelling. Seasonal temperature data were recorded in the central living space of buildings over a three month period. The research gathered dry bulb temperatures, surface temperatures, and humidity data in each building. Direct observations were made on the activities of the occupants within their thermal environment and they were surveyed regarding thermalcomfort levels. Results indicate that thermal mass impacts thermalcomfort levels of occupants. However, this impact can be negative or positive depending on other external factors such as the placement of thermal mass within the building, exposure of thermal mass to insolation and insulating materials around the thermal mass. In dwellings with poor thermal performance occupants can increase thermalcomfort levels by more closely adapting to the thermal environment. Such techniques for adaptation include: the adjustment of clothing; the use of controls such as windows and blinds; relocation within the building; changes in posture and levels of physical activity; and acclimatisation to the local climate.
contributing to rising sea levels, and this makes coastal cities vulnerable. The oldest weather station in the Netherlands is located in De Bilt. This weather data has been recorded since 1901. According to the historical data, the average air temperature has increased 1.4 °C between 1951 and 2013. This increase is twice the global average (KNMI 2015b). The Royal Netherlands Meteorological Institute (KNMI), as the Dutch national weather service has produced four climate scenarios based on IPCC fifth report (IPCC 2013) for 2050 and 2085. Based on these scenarios, air temperature increase for December, January and February (winter) is larger than March, April and May (spring). The temperature changes in the scenarios are briefly described in Table 1. Based on these future scenarios, urban spaces must be designed in a way to mitigate the impact of global warming on citizens` health. A practical way to make urban spaces ready for warmer futures is to adjust the albedo of surfaces. In the following section, the importance of high-albedo materials is explained.
Not only the values and trends of wind velocity, but the prevailing wind is also important in assessing the possibilities of outdoorthermalcomfort conditions. The results of wind characteristic analysis can be very useful especially for design team to finalise their design of building orientation and position in relation to other surrounding buildings. This in order to enhance building permeability for greater induction of wind that can reduce heat. Table 2 shows the trends of prevailing wind in Kuching from South-Southeast direction (150°), and from East-Southeast direction (110°) in Kota Kinabalu, with an average frequency of about 4.59% and 19.81% respectively. These results also indicated that both locations have different prevailing wind velocities throughout the years. However, their prevailing wind directions remained the same every year for each of the locations, except in 2014 where the prevailing wind direction in Kuching was from North (0°). In short, yearly weather data analysis for the three-year period show different wind directions. A more precise wind directions for both locations can be obtained if a longer study period is considered.
2016; Kántor, Égerházi, et al., 2012; Lin & Matzarakis, 2008; Lin, 2009; Mahmoud, 2011; Salata et al., 2016; Yang, Wong, & Zhang, 2013). Although this method was criticized by assuming that thermal sensation votes are continuous instead of ordinal data (Cheung & Jim, 2017), this impact was found to be insignificant (Salata et al., 2016). Few studies used the same method having the linear regression using different other thermalcomfort indexes (Pantavou et al., 2013; Yang, Wong, & Jusuf, 2013; Zhao, Zhou, Li, He, & Chen, 2016). PPET is the ultimate temperature in which the probabilities of users’ preferences towards having warmer and cooler changes are equivalent. To calculate PPET, a probit regression analysis for both warmer and cooler preferences is modelled and the intersection of both corresponds to the preferred temperature (Lin, 2009; Lin et al., 2011; Salata et al., 2016; Yang, Wong, & Jusuf, 2013; Yang, Wong, & Zhang, 2013; Zhao et al., 2016). TAR is the limit determining the temperature accepted by 80 or 90% of the respondents (ASHRAE, 2004). This range is generated from a quadratic regression between the thermal acceptability of the respondents and the temperature. Yang, Wong, and Jusuf (2013) calculated this range based on the assumption that 80% acceptability rate corresponds to the value of ±0.85 MTSV in the linear regression between the binned MTSV and the temperature as per ISO-7730 (2005). NPETR corresponds to the values ranging from -0.5 to +0.5 MTSV in the NPET linear regression (Chen et al., 2015; Kántor et al., 2016; Lai, Guo, Hou, Lin, & Chen, 2014; Liu et al., 2016; Salata et al., 2016). Different benchmarks obtained in similar OTC studies are summarised in Table 1, showing that the NPET is the most commonly used and the NPETR values are the least reported.