Supplementary material for: Effects of microclimatic and human parameters on outdoor thermal sensation in the high-density tropical context of Dhaka

The supplementary material has a separate DOI generated from ResearchGate: DOI: 10.13140/RG.2.2.30599.4496

Connecting the realms of urban form, density and microclimate

Av doktorgradsstudenter på norske universiteter, er det en fjerdedel som ikke fullfører innen normert tid. Det er lite forskning på hvorfor det er slik i Norge. Å øke gjennomstrømningen vil være nyttig for stipendiaten og har samfunnsøkonomisk gevinst. Denne studien har sett på faktorer som kan virke inn på engasjement og utbrenthet hos norske doktorgradsstudenter. Økt engasjement og mindre utbrenthet kan bidra til at flere fullfører innen normert tid og at færre hopper av doktorgraden. Først gjennomførte vi en kvalitativ studie hvor vi intervjuet 9 doktorgradsstudenter fra UiT Norges arktiske universitet. Vi spurte om hva de anså som stressfaktorer og ressurser i arbeidet deres. I tråd med internasjonal forskning opplevde studentene at sosial støtte fra veileder og forskningsgruppe var viktige ressurser. I tillegg var motivasjon og autonomi viktig for informantene våre. Jobb-familie-konflikt og liten tro på egen faglighet var stressorer i doktorgraden. Videre utførte vi en kvantitativ studie med et større utvalg fra til sammen fem universiteter (N = 256). For å finne krav og ressurser i arbeidet, benyttet vi jobbkrav-ressursmodellen. Våre funn var i tråd med modellen, som predikerer at høye krav gir mer utbrenthet, mens mye ressurser gir økt engasjement og mindre utbrenthet. De kvantitative resultatene bekreftet at sosial støtte og veiledning var viktige ressurser. Av krav var jobb-familie-konflikt fortsatt sentral, mens arbeidsintensitet framkom som en ny type krav. Et annet nytt funn, var at opplevd kompetanse delvis medierte effekten fra ressurser til engasjement, og den svekket i tillegg forholdet mellom krav og utbrenthet. Gjennom å styrke ressursene hos doktorgradsstudenter kan jobbengasjement øke og utbrenthet minske. Dette kan føre til økt produktivitet og mindre ønske om å slutte i jobben. Dette vil ha ekstra effekt hvis det også rettes fokus mot å styrke opplevd kompetanse hos stipendiaten. Disse tiltakene kan bidra til at flere fullfører doktorgraden innen normert tid og at færre dropper ut. Nøkkelord: norske doktorgradsstudenter, phd, jobbkrav-ressursmodellen, stress, utbrenthet, engasjement

Impact of urban geometry on indoor air temperature and cooling energy consumption in traditional and formal urban environments

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the URI link.This study explores the effect of outdoor microclimatic environment on indoor conditions in a tropical warm-humid climate. An indoor air temperature and building energy performance analysis is carried out for the real case-study areas to examine the impact of urban geometry on building indoor conditions. The study incorporates microclimatic data from CFD, micro-climatic tool ENVI-met into building energy performance analysis using IES-VE. Findings reveal that diversity in urban geometry in deep urban canyons is helpful in reducing the indoor air temperature and cooling load. On average, cooling load in model rooms in the formal area is 21% higher for 1st floors (40% for top floors) compared to the corresponding rooms in the traditional area. In terms of solar gains, the difference was 30% for the 1st floors and 91% for the top floors, with rooms in the formal area having the higher ranges. Furthermore, the room air temperature in the traditional area was found to be 0.6-1.6 Deg C lower than those in the formal area

Characterising living wall microclimate modifications in sheltered urban conditions

Green infrastructure enhancements are widely advocated to address heat-related risks in cities. The challenge of implementing enhancements in dense cities has necessitated the development of surface greening, with living walls having gained increased prominence in recent years. This paper considered such in-situ applications to quantify the extents of their influence on the microclimates of two sheltered urban conditions. The results highlight the potency of hygrothermal modifications to be most apparent within the immediate zone, while the disparity in influence between the two studies suggest that with increased shelter the hygrothermal influence is likely to be relatively weaker. Surface temperature monitoring results from the Indoor case study presented significant variation. While these were not potent enough to cause radiation asymmetry associated discomfort, thermal sensation and diversity to occupants is probable. These findings therefore highlight the necessity for designers to take account of this proximity influence, and in future designs to increase building occupant access to installations.UK Engineering and Physical Sciences Research Council [doctoral studentship 1930753]

Impact of urban geometry on indoor air temperature and cooling energy consumption in traditional and formal urban environments

This study explores the effect of outdoor microclimatic environment on indoor conditions in a tropical warm-humid climate. An indoor air temperature and building energy performance analysis is carried out for the real case-study areas to examine the impact of urban geometry on building indoor conditions. The study incorporates microclimatic data from CFD, micro-climatic tool ENVI-met into building energy performance analysis using IES-VE. Findings reveal that diversity in urban geometry in deep urban canyons is helpful in reducing the indoor air temperature and cooling load. On average, cooling load in model rooms in the formal area is 21% higher for 1st floors (40% for top floors) compared to the corresponding rooms in the traditional area. In terms of solar gains, the difference was 30% for the 1st floors and 91% for the top floors, with rooms in the formal area having the higher ranges. Furthermore, the room air temperature in the traditional area was found to be 0.6-1.60C lower than those in the formal area

Effect of canyon geometry on outdoor thermal comfort: A Case-study of high-density, warm-humid climate

A successful urban planning and design solution ought to present a comfortable setting for its pedestrians inside urban canyons, because it is fundamental to encourage a good quality urban life and promote health and wellbeing of humans. Recent findings have demonstrated that microclimate inside urban canyons has substantial influence upon the outdoor thermal comfort at the street level .This study, therefore, intends to devise early stage building and urban design strategies to improve outdoor thermal comfort. For this study, a number of existing urban canyons in Dhaka city have been chosen with a range of geometries combined with a variety of street orientations. The microclimatic characteristics of the canyons are analysed through a high resolution CFD microclimatic model: ENVI-met Version 4. Thermal comfort was evaluated with the PET index with the aid of RayMan1.2. Important findings include that deeper street canyons result in reduced air temperature but increased Tmrt thus presenting apparently conflicting design options to achieve outdoor comfort. However, such apparently conflicting findings offer the potential for designers to find a variety of canyon geometries appropriate for a tropical city context

Understanding ENVI-met (V4) model behaviour in relation to environmental variables

A parametric analysis is carried out to understand how ENVI-met (V4) responds to the following aspects which form the basis of understanding the model’s behaviour: i) canyon aspect ratio, ii) cloud cover, iii) orientation, iv) wind speed and v) building height variability. The reason for using parametric modelling is that modelling techniques and calculations are made easier as they are applied to simple models and, thus, the process is verified prior to examining the real, complex situations. This is helpful for understanding the links between simple urban form and the resultant environmental characteristics and to determine the model boundary conditions for comparing the real situations. The results of the simulations include: the maximum and average (median) values of air temperature decreases in deeper canyons, but the rate of reduction reduces for canyons with an H/W ratio over 2. The average (median) mean radiant temperature also reduces in deeper canyons, but the trend is not linear. Air temperature is not affected by canyon orientation, whereas Tmrt is significantly affected by canyon orientation as the EW canyon remains exposed to high Tmrt for 8.5 hours while NS canyon is exposed for only 2.5 hours. Windy conditions result in a slightly higher air temperature and a lower Tmrt level compared to still air conditions. Increase in cloud cover has a decreasing effect on air temperature and Tmrt. And finally, the impact of diversity in canyon geometry has little impact on air temperature and Tmrt conditions

Harmonious accordance of indoor-outdoor thermal comfort and building energy performance by ameliorating urban microclimate in different urban block types in tropical climate

This paper explores the effect of outdoor microclimatic environment upon indoor conditions for different urban block types in hot-humid climate. The main focus here is on courtyard patterns, considering its potentials for hot-humid climate is not fully understood yet. Courtyard spaces have been examined in conjunction with the internal spaces of surrounding buildings with the aim to create a link between both. Based on theoretical models, it intends to devise strategies to optimise both indoor-outdoor thermal comfort and building energy performance while enabling the building designers and urban professionals to consider these essential issues at the early design stage. For this study, four simplified archetypal urban arrays are selected, primarily developed by Martin and March. These are: pavilions, enclosed courtyard pavilions, open-square and open-rectangular courtyard pavilions. Firstly, it has observed the microclimatic characteristics of the geometric patterns through a high resolution CFD microclimatic model: ENVI-met. Thermal comfort in the adjacent and enclosed outdoor spaces was assessed against Physiological Equivalent Temperature (PET) index with the aid of Rayman 1.2. Secondly, the energy performance of the surrounding buildings was analysed by IES-VE: a building performance modelling tool. The methodology and results from the current study can be integrated in the future urban planning processes in a high-density warm-humid context

Effects of microclimate and human parameters on outdoor thermal sensation in the high-density tropical context of Dhaka

Funder: Schlumberger Foundation; doi: http://dx.doi.org/10.13039/100002322Abstract: 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 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 outdoor thermal 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 meteorological model) and ‘Hot’ (64.9% in combined parameter model) categories—the most important ones in a hot-humid climate

Use of microclimate models for evaluating thermal comfort: identifying the gaps

The study identifies the gap between actual thermal sensation and theoretical comfort calculated through simulated microclimate data in different urban configurations in a tropical, high-density, megacity: Dhaka. The methodology stated here could be applied for evaluating outdoor comfort conditions for future urban areas at an early design stage. To apply the concept of theoretical comfort it is important to understand its limitations and degree of deviation from the actual comfort conditions at real scenarios. This study mainly focuses on traditional and formal (contemporary) residential settlements with different urban-geometry features. On-site climatic measurements were carried out during the hot-humid months and were compared with simulation results calculated through ENVI-met 4. Simulation results were found to have good agreement with actual air-temperature, mean radiant temperature (Tmrt) and relative humidity. In terms of windspeed, the simulated model for a complex traditional settlement did not successfully match with the actual scenarios. However, this does not affect the model competency, because, the area has rather unusual wind pattern due to its location and current arrangements of buildings. The simulated results were subsequently used to calculate outdoor thermal comfort using the PET index in RAYMAN Pro. The calculated theoretical comfort was assessed against Actual Thermal Sensation Votes (ASV) obtained through a thermal comfort survey in the case-study areas. Strong correlation (r=.58) was found between theoretical and actual comfort in the formal settlements, while the comparison with the traditional settlements produced rather weak results (r=.238). This leads to the understanding that theoretical comfort can be a useful tool for comparing between regularly planned sites; however, for complex urban geometry, theoretical comfort can deviate from actual comfort levels recorded, in part due to adaptive behaviour