Adverse microclimatic conditions greatly affect the thermal comfort, health and wellbeing of people in urban outdoor spaces. For tropical countries in particular, the implications of thermal stress on health and productivity needs to be tackled largely by proper urban and building design details that are affordable. To address this need, recent studies have examined the relationship among microclimate, thermal comfort, and human behaviour with the aim to provide guidelines and implications for outdoor space design and planning practice. Important studies in a tropical climate include (Hirashima et al. 2016; Ignatius et al. 2015; Villadiego & Velay-Dabat 2014; Yang et al. 2013; Johansson et al. 2018) etc. which provide an extensive knowledge of the effects of outdoor climatic conditions on people’s thermalsensation. However, there has been a limited amount of research in these areas focussing on the tropical megacity of Dhaka. As one of the worst victims of climate change, Dhaka is particularly vulnerable with poor outdoormicroclimatic conditions exacerbated by the urban heat island (UHI) effect (Kotharkar et al. 2018; Santamouris & Asimakopoulos 2001) and an elevated level of air pollution (Carlsen et al. 2018; Begum et al. 2011; Azad & Kitada 1998). This makes outdoor comfort research particularly important for Dhaka, since outdoor spaces- users are exposed to severe heat-stress during the most part of the year. The only scholarly work concerning outdoorthermal comfort and urban microclimate was carried out by (Ahmed 2003). The study, however, did not identify the impact of various parameters on outdoorthermal comfort other than the environmental ones. It mainly emphasised specific microclimatic features, such as the presence or absence of greenery, proximity to a river etc. No prediction tool was proposed. This study, therefore, intends to contribute in understanding the impact of various personal and psychological parameters alongside meteorological parameters on thermal perception in order to be able to identify priorities in climate-responsive urban design.
‘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.
Received: 6 December 2017 / Revised: 13 July 2018 / Accepted: 25 August 2018 # The Author(s) 2018
A thermal comfort 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 thermalsensation. 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 outdoorthermalsensation in the case study areas. Ordinal linear regression techniques are applied for predicting thermalsensation 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 thermalsensation 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 Outdoorthermal comfort . Questionnaire survey . Thermalsensation vote (TSV) . Predictive model . Tropical climate
Urban microclimate has important consequences on the thermalsensation of pedestrians. However, the extent of this effect may vary as other parameters such as respondents’ personal factors, psychological and behavioural aspects and cultural backgrounds may be involved. This heightens the need for subjective assessment and on-site questionnaire surveys alongside objective field measurements to understand outdoor comfort conditions which is essential for creating sustainable urban spaces. In this study thermal comfort conditions outdoors are examined through field surveys in the high-density, tropical city Dhaka, where extensive microclimatic monitoring has been carried out in parallel to subjective responses of the pedestrians. Microclimatic conditions, which are affected by the urban geometry, are found to be statistically correlated with thermalsensation votes (TSV), with air temperature, globe temperature and mean radiant temperature being the most important parameters (correlation coefficients of r = 0.47, 0.45 and 0.44 respectively). The study also reports the effect of urban geometry parameters on microclimatic conditions, identifying strong correlations with globe temperature (r =-0.50), mean radiant temperature (r =-0.48) and wind speed (r =0.72). Furthermore, the study proposes acceptable ranges (upper limits) for PET for the tropical climate of Dhaka with a ‘Neutral’ range between 29.5 0 – 32.5 0 C confirming that people in outdoor conditions will feel
All discretization levels mentioned in the subsection 4.4 have already been coupled with CFD. Omori et al.  coupled an accurately modelled human body in CFD with the Fanger PMV model using a combination between total heat flux and body surface temperature. Murakami et al.  coupled a simplified model of the human body in CFD with the two-node Gagge model. Tanabe combined his 65 multi-node model with a radiation exchange model and CFD. (Tanabe et al. ) In this study, the 33 NCM is coupled with CFD using the commercial flow solver ANSYS CFX 12. The change from version 11, used for the other CFD calculation, to version 12 for coupling was necessary for achieving a stable extraction of the variables during the run of the solver. The system is designed using text scripts and user routines to interact with the CFD solver. The 33 NCM divides the human body into 16 body segments. The virtual manikin for the CFD calculations, al- ready used for the cabin simulation in the subsection 6.5, also provides all 16 body segments. For each of these 16 body segments, the comfort model delivers the thermal boundary conditions as surface temperatures. The human heat flux to the environment is the new boundary condition for the thermal comfort calculations. The heat flux is subdivided into convective and radiative heat flux by transposing the total heat flux and the convective heat transfer coefficient. For calculating evaporative heat loss, it is necessary to extract the average environmental temperature of the flow domain as it affects the saturate vapour pressure on the skin surface. At the end of time step in the CFD simulation cycle, those 33 variables are extracted into a text file. The CFD model then waits for the 33 NCM. The 33 NCM uses those data to predict new surface temperatures, local and global overall thermalsensation and comfort. This means that altogether 50 variables are fed back into the CFD calculations. These are loaded into the CFD model, and the CFD simulation resumes. Figure 10.9 illustrates the coupled scheme with its used variables. The left hand side shows the segmented person model used in the flow simulation. On the right hand side, the Modelica model with its 83 connectors can be seen.
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Figure 3. (a) CFD mesh and boundary conditions (b) grid sensitivity analysis 4. Results and Analysis
Figure 4 compares the predicted temperature contours of a side view cross-sectional plane inside the computational domain representing the thermal distribution around the manikin with heated office chair and normal chair. As observed, the thermal chair (Figure 4a) heated the seat and back rest areas between 28- 36˚C. While for the case of the space heated with underfloor air jets, the temperature around the manikin range between 24- 28˚C as observed in Figure 4b. For both cases, lower temperature near the face area was observed due to higher airflow movement while a higher temperature can be observed near the seat area and thigh region due to lower air movement and constrained space. From the results it was evident that depending on the position of the user (in this case a manikin), the seat and back rest regions had different temperature levels. The results indicated the necessity of separate control systems for the seat and the back which was implemented in the design of the thermal chair.
This study investigated the accuracy of neutral thermalsensation as the measure of thermal comfort through the application of a thermal chair. The prototype of an office chair equipped with heat pads on the seat and the back of the chair with separate temperature controls was designed , as illustrated in Figure 2. The application of this thermal chair was examined through field studies of thermal comfort in an open plan office in the University of Leeds in the winter of 2014, where 44 occupants with mainly sedentary activities participated in the research. This was the real context of the office and participants continued with their normal everyday activities during the study. Respondents were mainly in their twenties and thirties and they included 15 females and 19 males. Their views of comfort, satisfaction and thermal comfort (presented in Table 1) were recorded before and after an hour of using the thermal chair, as presented in Figure 2. As explained separate manual control systems were provided for the seat and the back of the chair and occupants were briefed on using them. The temperature settings of the chair for every participant were recorded and the satisfaction of the respondents regarding the use of the thermal chair was investigated. A good practice example of the workplace with a good quality of thermal environment was selected for this study to limit the impact of the thermal environment on occupants’ thermal decision. For this reason, the thermal environment was measured (dry bulb temperature, humidity and mean radiant temperature). Accordingly, the PMV was calculated and it was compared against the ASHRAE Standard 55-2013, which was satisfactory.
Studies show that thermal control increases user thermal comfort . Thermal chair has been studied in several studies, mainly as a ventilated or cooled chair [15-17], as demonstrated in Figure 1. The ventilation was either designed in the armrests of the chair , back or seat [16,17]. Watanabe et al provided separate control systems for the seat and the back . Zhao et al combined the back and seat fans with heating elements on the back and the seat of the chair for the use in both the cold and warm season , as illustrated in section c in Figure 1.
There are many indices that have been suggested and employed throughout the open literature to assess the outdoorhumanthermal comfort. Throughout the literature; there are about 40 indices of thermal comfort . Some of these indices, such as the Discomfort Index (DI) , Robaa index (RI)  , and the Predicted Mean Vote index (PMV)   merit special mention as they appear continuously in literature. The Discomfort Index was first proposed by Thom in 1959 . It is an empirical index based on a large series of observations and it is only function of air dry bulb temperature and relative humidity. The second index is the Robaa index . It is suggested by Robaa  to account for the combined effect of the three weather elements, dry bulb air tempera- ture, relative humidity and wind speed, on the human discomfort. The range of applicability of RI is wide and it was proven to be adequate for Egypt’s climate . It illustrates the integrated effect of both wind speed and rel- ative humidity changes on the humanthermal comfort. In this study, both DI and RI are employed for three ma- jor cities in Egypt in order to clarify the effect of the differences in climate at the northern, middle and southern parts of Egypt on outdoorhumanthermal comfort. The cities are: Alexandria city which is located in the north of Egypt, Cairo the capital of Egypt which is located in the middle and Aswan city which is located in the south of Egypt (See Egypt map in Figure 1). The study investigation is based on the mean hourly measured meteoro- logical data for the three cities, over a period of thirteen months ranging from January 2011 to January 2012.
The development of an SFR (sodium fast reactor) as one of the advanced reactor systems requires new fuels, claddings, and structural materials. To characterize the performance of these new materials, it is necessary for us to have leading-edge technology applied under the specific test requirements, such as the conditions of high neutron exposures (~ 200 dpa), high operating temperatures (390-700 ) and a specific chemistry (Na). The existing design concept of a capsule, however, is not satisfactory for the high temperature tests. Thus, various approaches, i.e. usability of several test holes of HANARO, applicability of new materials as a cooling medium and design changes such as the internal geometry and shapes of a capsule, have been investigated at KAERI (Kang, 2008a). In particular, literature surveys about the system design characteristics of various irradiation devices being developed or used in the foreign research reactors(i.e. ATR (Grover, 2004), MITR (Hu, 2005), JHR (Carrasou, 2005), which are helpful in understanding the key issues for the on-going R&D programs related to a SFR, were conducted to develop new design concepts. For an application of the high temperature irradiation tests in the HANARO reactor, the candidate thermal media should have a high gamma heat rate, which is needed to obtain the required temperature, and a proper thermal resistance with high conductivity which allows a small temperature difference within the specimens. From an extensive survey of the literature, one of the candidate thermal media was selected as an LBE (44.5w/o Pb+55.5 w/o Bi) for the high temperature irradiation devices. LBE has been a candidate for high power spallation neutron target (Tsujimoto, 2005) and nuclear coolant due to its proper chemical, thermal, physical, and nuclear properties (Gromov, 1999). However, the corrosion problem for steels becomes a critical barrier for the high temperature and longtime application. Many researchers have shown that these problems will be solved near future with the introduction of advanced technologies. At present, LBE is expected to perform reliably well at relatively high temperature.
The issue of the thermal-hygric microclimate (THM) is addressed in Slovakia by several de- crees, government regulations and several STN standards (taken from international standards). The objectivization of the physical quantities of the thermal and humidity microclimate is carried out following the Professional Guideline of the Ministry of Health of the Slovak Republic , which regulates the procedure for the measure- ment and assessment of the thermal-hygric micro- climate. In order to assess the fulfilment of ther- mal-hygric microclimate requirements at work, the basis is the results of direct or indirect mea- surement and their comparison with the values of parameters set out in decrees and laws [26÷28]. In accordance with decrees the thermal-hygric microclimate is part of the overall microclimate of the working environment and its most impor- tant factors are the air temperature (t a ), the mean radiant temperature (t r,m ), the relative air humid- ity (r h ), the air flow velocity (ν a ) and the stereo temperature (t st ), which are made objective by measurement and established the limit values for determining the parameters of the thermal-hygric microclimate for individual types of work de- pending on the thermal production of the organ- ism during the performance of the work activity.
Likewise, in the study by Metje et al. (2008), the pedestrians’ comfort level in outdoor and semi- closed spaces at the university campus was evalu- ated conducting a field measurement and question- naire survey concurrently. They found the wind speed and the air temperature affect the humanthermal comfort, while, it is difficult for respon- dents to distinguish the role of solar radiation and humidity on thermal comfort. In addition to mi- croclimate parameters, they confirmed subjective adaption extremely influences on humanthermal comfort. Similarly, in the research by Hwang and Lin, (2007) six distinctive semi-open locations were investigated in order to discover the thermal com- fort demands for inhabitants in semi-closed areas using SET* thermal index. Their significance result is that in contrast to dwellers of easily restrained en- vironments, inhabitants of difficult conditions are more comfortable at higher temperature. Further- more, they expressed the potency of global radia- tion to modify the humanthermalsensation is more powerful in comparison with air movement. Finally, they concluded in hot and humid climate, enhanc- ing the wind speed and diminishing the amount of direct sun light in design concepts, can impressive- ly improve the comfort level of individuals in semi- outdoor spaces.
The world is at its fastest pace of urbanization. Since 2008, more than half of the world’s population live in urban areas. The trend in global population increase has led to an increase in housing demand. Singapore has gone from one of the worst housing shortages in the world in the 1960s to a country where 90% of its citizens now own their own home and homelessness is virtually eliminated—despite its population has tripled in the last 50 years. With success of housing policies, natural land has been replaced by artiﬁcial surfaces in Singapore with undesirable thermal eﬀects. This issue, to- gether with increasing industrialization, has caused a con- siderable deterioration of the urban environment. In tropical countries like Singapore, hot climate in terms of high tem- perature, high humidity, and high solar radiation often causes heat stress to residents, resulting in negative impact on public health and productivity. Climate-responsive urban design can create microclimates that people experience as feeling cooler than the prevailing climate, making urban spaces pleasant.
The majority of natural fibres, as a function of cellulose fibres and lignin, have low degradation temperatures (~200 °C), making them inadequate for processing temperature above 200 °C (Pracella et al., 2006). Nair et al. (2001) reported that the Tg values of polystyrene composites reinforced with short sisal fibres are lower than that of the unreinforced PS and may be attributed to the presence of some residual solvents in the composites. To solve the processing of natural fibre composites, it is necessary to promote polymer modification with polar groups (such as maleic anhydride, stearic acid or glycidyl methacrylate) to enhance the adhesion between the matrix and the composite components. The coupling agent more often used for this application is a polyethylene copolymer grafted with maleic anhydride (Keener et al., 2004). In this paper, the investigation of tensile properties resulted in an optimum condition of composites, meanwhile thermal behaviour within the optimum condition from abaca fibre reinforced HIPS composites at glass transition and crystallization processes was clearly observed. Commercial HIPS were used for a comparator to the natural fibre composites. The DSC methods were used in evaluating the basic thermalparameters of the optimum condition of abaca fibre reinforced HIPS composites.
The industrial materials studied here are highdensity polyethylene which has been formulated utilizing vari- ant concentrations of nanoparticles of clay and fumed silica. Highdensity polyethylene nanocomposites have been prepared and fabricated by using recent nanotech- nology procedures and devices for melting pure highdensity polyethylene grains, mixing and penetrating nanoparticles inside the base matrix HDPE by modern ultrasonic devices. Most of all nanocomposite materi- als are commercial and available already in the manu- facturing of High-Voltage (HV) industrial products and their properties detailed in Tab. 1.
to reach thermodynamic equilibrium and, following that, the exchange of the carrier gas from nitrogen to oxy- gen was conducted, maintaining the same flow and isotherm for a maximum 90 minutes. The OIT test was per- formed with the purpose of evaluating the thermal stability of the material at each temperature. With the OIT result, a time reference to which the sample can be subjected is obtained, without oxidative degradation. Or even the opposite, that is, a minimal time reference so that the oxidative degradation of the sample can occur.
was able to be produced in bulk quantities, which inspired scientists worldwide to explore its fascinating chemistry, and it has now become the most intensely researched single molecule in modern science [1–3]. A significant aspect of the C 60 chemistry is its high reactivity towards free radicals, and
The scope of the research focuses on high-rise office buildings in the tropical climatic of Malaysia. The scope of the research is limited to the golden triangle area in Kuala Lumpur because a lot of high-rise buildings are located within the area. A high-rise office building called the Cap Square tower, which is situated at Jalan Munshi Abdullah in Kuala Lumpur, was selected as a case model. Cap Square Tower was selected because it fulfills the criteria of a tropicalhigh-rise building as mentioned by Ken Yeang (1994); Kannan (1991) and Mineki Hattori (1984) in terms of the building shape (rectangular) and the position of the core location in the building, which is at the central of the high-rise office building. The building is designed with a curtain wall at the 4 sides of the façade and the case model high-rise office building is without balcony, but with exterior light shelves. In order to investigate about the effect of balcony on high-rise office building, a 3D model of the case model of the high-rise office building was modeled into two types; which are; the model with the balcony and the model without the balcony. Based on the review of previous researches as such Li et al. (2003); Hossam El Dien and Woloszyn, (2004); Tang (2010); Myung Jun Kim and Ha Geun (2007); and Pyoung Jik Lee et al. (2007), a rectangular form of balcony have been widely used in high-rise buildings, therefore, a rectangular form of balcony is selected to be modeled on the façade of the 3D model of the high-rise office building with the balcony.
3.0 DATA COLLECTION
This study involves a comprehensive data collection for twenty- five pedestrianized locations within Kano Metropolis in North- West Nigeria. Thirteen locations were identified in the city district while twelve locations were outside the city district called the Waje District. The pedestrians were observed for speed and volume as well as their walking behaviour. All the observation points were outdoor walkways along road corridors characterized by dense pedestrian flows. In order to reflect dense flow conditions, the data was re-organised to remove singularities in the movement. Pedestrian behaviour were segregated into male, female, adult and the young. To determine the speed of a pedestrian, a measured course was predetermined and a randomly picked pedestrian in a typical dense flow situation was timed over this measured course of 30 m. The 30 m measured course was used because pedestrians consistently covered this distance without changing their behaviour. The flow rate was abstracted form video recordings every 30 minutes during the observation period which lasted from 8.00am to 6.00pm daily for seven days during the month of July 2013.The speed measurements were manually captured while video technology was used for observing the flow rate and pedestrian behaviour. In all cases, the observation period was during daylight, weekdays and weekends and during normal weather conditions. The sample size for the city district was 15,106 while that of the Waje district was 9,093.