Over the last decade, rapidly growing world energy consumption is leading to supply difficulties, exhaustion of fossil energy resources, and global environmental deterioration. More than one-third of energy expenditure is attributable to buildings. Urbanization is intensifying these trends with tighter spatial interrelationships among buildings. This is escalating building energy consumption due to the mutual impact of buildings on each other and, as a result, exacerbating Urban Heat Island (UHI) effects. I sought solutions to this significant engineering issue from nature, and discovered a similar heat island effect in flowers, namely the micro-greenhouse effect. However, a special cooling effect has been observed in a peculiar temperate flower, Galanthus nivalis, which generates cooler intrafloral temperatures. In this research, I studied the special retro-reflectance of the flower petals, which has been suggested as a possible contributor to this cooling effect, and implemented a bio-inspired retro-reflective pattern for building envelopes. I conducted cross-regional energy simulation of building networks in a dynamic simulation environment in order to examine its thermal-energy impact. I found that building surface temperatures dropped considerably when neighboring buildings were retrofitted with my bio-inspired retro-reflective facade. I concluded that my bio-inspired retro-reflective pattern for building envelopes; (1) lessens the reflected heat of solar radiation in spatially-proximal buildings leading to reduced UHI, and (2) reduces the energy required for cooling and, therefore, energy consumption. The research has further implications and contributions on building design, urban planning, development of retro-reflective technology, and environmental conservation. / Master of Science

Climate change will increase the intensity and duration of heat waves in Sweden. Vulnerable communities are especially affected by the effects of heat waves and since children rely on adults to provide comfort, children are particularly affected by heat wave impacts. The aim of this study was to characterize how preschool children and preschool activities were affected by heat exposure based on the perspectives of preschool educators. Six group interviews were conducted with twelve preschool educators in Linköping and Norrköping and the data was analyzed using reflexive thematic analysis. The results indicate that the lack of shaded areas in the preschool yards causes considerable negative impacts on the health of preschool children and obstructs suitable preschool activities. Future research should explore the possibilities of connecting urban planners with preschool educators in the planning phase of preschools in order to utilize their experiences on how to mitigate the effects of heat waves on preschools. / BRIGHT

Syftet med studien var att kartlägga urban heat island [UHI]- och klimatanpassningsåtgärder som London och Stockholm arbetat med för att reducera UHI-effekten i respektive stad. Eftersom London upplever en högre UHI-effekt har de därmed kommit längre i deras arbete, studien fokuserade därför även på att förstå vad som är bakgrunden till att Stockholm brister i sitt arbete. En semikvalitativ innehållsanalys användes för att besvara frågeställningarna. Tre statliga dokument från respektive stad analyserades genom kodning och kategorisering. Åtgärderna som hittades graderades utifrån typ av åtgärd (åtta olika kategorier) och nivå på åtgärd (planerad, pågående eller genomförd). Resultatet visade att London har ett mer utförligt och proaktivt arbete med att motverka UHI än Stockholm, dels för att de lyfte budget och investeringar för deras olika åtgärder. Projekten är även större och omfattar fler områden än Stockholm. Stockholm har därmed mycket att hämta från Londons UHI- och klimatanpassningsarbete. Trots att Stockholm hade fler åtgärder är det inte lika omfattande och utvecklade jämfört med London som hade större projekt, program och policys. Resultatet visade att fler åtgärder genomförts i London. Det framgick att attityden skiljer sig åt mellan städerna. Stockholm måste förstå allvaret och borde påskynda sitt arbete genom att lägga ner mer resurser och samarbeta med aktörer för att säkerställa att projekten uppfylls och underhålls. / The purpose of this study was to map the urban heat island [UHI] and climate adaptation measures that London and Stockholm are implementing to reduce the UHI effect. London experiences a higher UHI effect, and therefore are more advanced in their work in contrast to Stockholm. The study employed a semi-qualitative content analysis, in addition with three government documents from each city which were analysed through coding. The measures found were categorised according to type of measure (eight different categories) and level of measure (planned, ongoing or implemented). The results showed that London has a more comprehensive and proactive approach to tackling UHI than Stockholm, through raising budgets and investments for their various actions, larger projects, and projects that cover more areas than Stockholm. Stockholm can utilise the development of London's UHI and climate adaptation work to better fix their issue. Although Stockholm has more measures, these are not as extensive and developed compared to London, which has larger projects, programmes and policies, in addition with more active measures being implemented in London. From the analysis it was evident that attitudes differ between Stockholm and London. Stockholm needs to understand the seriousness and should accelerate its work by putting more resources and collaborating with stakeholders to ensure that projects are fulfilled and maintained.

With the urbanization of Swedish cities, densification has emerged as a sustainable ideal in urban planning. As new buildings and hard surfaces replace more green spaces and open areas, the Earth´s climate is becoming warmer, and the consequences of rising temperatures are becoming more tangible. In densely built environments, the warm climate is further exacerbated due to the urban heat island effect, which means that the temperature difference between urban and rural areas can reach several degrees. This affects the local climate and has serious consequences for the people who live and stay in the cities, including increased heat stress and health risks. Through climate-conscious planning, where heat-reducing measures are implemented, the heat island effect can be mitigated and thereby creating favorable urban climates. This work focuses on the impact of the densification ideal on the heat island effect and human living environments. In the literature review, heat islands and their consequences are discussed to emphasize the importance of planning for rising temperatures and to identify temperature-reducing measures. The study examines a typical densification project to understand how heat-reducing measures can be integrated into existing urban areas and suggest actions that should be introduced early in the planning process. The measures have been proposed using two methods; a qualitative document study and a site analysis. The site analysis conducted in Ebbepark, Linköping aimed to create an understanding of aspects in the built environment. Through the site analysis and document study, proposals for measures were developed, which then formed the basis for the design proposal in Ebbepark. The results showed that the integration of heat-reducing measures in densely built areas significantly contributes to the improvement of people´s living environments by counteracting the heat island effect and creating a more pleasant microclimate. Implementation of vegetation, high-reflective materials, and water features results in significant temperature reductions. To effectively counteract the heat island effect, these measures can be integrated into urban planning, both in new and existing densification areas. Heat-reducing measures should also be incorporated into municipalities’ overall planning documents to promote the development of sustainable and resilient urban environments. / I takt med urbaniseringen av Sveriges städer har förtätning växt fram som ett hållbart ideal i den fysiska planeringen. Under tiden som ny bebyggelse och hårdgjorda ytor ersätter allt fler grönområden och friytor blir jordens klimat allt varmare och de stigande temperaturernas konsekvenser mer påtagliga. I den tätbebyggda miljön förstärks det varma klimatet ytterligare med anledning av den urbana värmeöeffekten, som innebär att skillnaden i temperatur mellan stad och landsbygd kan nå flera grader. Detta påverkar det lokala klimatet och får allvarliga konsekvenser för de människor som bor och vistas i städerna, däribland ökad värmestress och hälsorisker. Genom en klimatmedveten planering där värmereducerande åtgärder implementeras kan värmeöeffekten mildras och därmed goda stadsklimat skapas. Arbetet handlar om förtätningsidealets påverkan på värmeöeffekten och människans livsmiljö. I kunskapsöversikten behandlas värmeöar och dess konsekvenser för att betona vikten av att planera för stigande temperaturer samt för att kunna identifiera temperaturreducerande åtgärder. Arbetet undersöker ett typiskt förtätningsprojekt för att förstå hur värmereducerande åtgärder kan integreras i befintliga områden och föreslår åtgärder som bör införas tidigt i planeringsprocessen. Åtgärderna har föreslagits med hjälp av två metoder; en kvalitativ dokumentstudie och en platsanalys. Platsanalysen som genomförts i Ebbepark, Linköping syftade till att skapa förståelse för aspekter i den byggda miljön. Genom platsanalysen och dokumentstudien kunde förslag på åtgärder tas fram, vilka sedan lade grund för gestaltningsförslaget i Ebbepark.  Arbetets resultat visade att integreringen av värmereducerande åtgärder i tätbebyggda områden avsevärt bidrar till förbättringen av människors livsmiljö genom att motverka värmeöeffekten och skapa ett mer behagligt mikroklimat. Implementering av vegetation, högreflekterande material och vatteninslag resulterar i betydande temperaturminskningar. För att effektivt motverka värmeöeffekten kan dessa åtgärder integreras i den fysiska planeringen, både i nya och befintliga förtätningsområden. Värmereducerande åtgärder bör också införlivas i kommuners övergripande planeringsdokument för att främja utvecklingen av hållbara och motståndskraftiga urbana miljöer.

Consequences of human activity in natural environments can be observed in urban phenomena. Urban Heat Island is one of those consequences, it is characterized by higher temperature levels in surface-cover and air in urban centers compared with its surrounding rural areas. UHIs are present in cities of arid ecosystems such as Phoenix and Tucson. Existing urban development trends contribute to UHI episodes. Urban Agriculture (UA) is an emerging environmental strategy and, contrary to traditional and industrial agricultural methods, UA systems provide the option of not using soil, its geometrical arrangement lets grow crops disregarding of extensive surface of land to be consumed. UA systems can be implemented as building fabric components. Urban Agriculture provides access to healthier and economic food, it is more energy efficient and promotes a more vegetarian diet which can eventually contribute diminishing health problems such as obesity and toxicity. A response for achieving a decrease in temperature levels in an urban arid region scenario can be established by demonstrating the following premise: "Urban Heat Island effect in arid regions can be mitigated if vegetated surface in the form of agriculture is properly integrated in the built environment". Research procedures were applied at building scale. Results involved physical objective data acquisition. Research methods required the use of software and thermodynamic tools to measure thermal behavior of samples. The impact of vegetated cover in temperature levels and thermal comfort in an outdoor scenario was digitally simulated. The selected research case contributed as a source of data for comparison and baseline benchmarking of thermodynamic circumstances. Employment of green infrastructure in cities can contribute to the improvement of energy efficiency in buildings and developing self-sufficient communities. Urban agriculture comprises implications and side beneficial environmental consequences in arid habitats beyond decreasing temperature levels in cities, such effects are energy conservation, reducing air pollution, diminishing food security concerns, improving soil quality and runoff wastewater as well as cutting down fossil fuel use in transportation of food. In that sense, future research fields include water quality and availability, innovative emerging materials, climate analysis, societal and cultural value, Net zero development and energy efficiency as well as solid waste management.

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

<p>As the world population continues to grow past seven billion people and global challenges continue to persist including resource availability, biodiversity loss, climate change and human well-being, a new science is required that can address the integrated nature of these challenges and the multiple scales on which they are manifest. Sustainability science has emerged to fill this role. In the fifteen years since it was first called for in the pages of Science, it has rapidly matured, however its place in the history of science and the way it is practiced today must be continually evaluated. In Part I, two chapters address this theoretical and practical grounding. Part II transitions to the applied practice of sustainability science in addressing the urban heat island (UHI) challenge wherein the climate of urban areas are warmer than their surrounding rural environs. The UHI has become increasingly important within the study of earth sciences given the increased focus on climate change and as the balance of humans now live in urban areas. </p><p>In Chapter 2 a novel contribution to the historical context of sustainability is argued. Sustainability as a concept characterizing the relationship between humans and nature emerged in the mid to late 20th century as a response to findings used to also characterize the Anthropocene. Emerging from the human-nature relationships that came before it, evidence is provided that suggests Sustainability was enabled by technology and a reorientation of world-view and is unique in its global boundary, systematic approach and ambition for both well being and the continued availability of resources and Earth system function. Sustainability is further an ambition that has wide appeal, making it one of the first normative concepts of the Anthropocene. </p><p>Despite its widespread emergence and adoption, sustainability science continues to suffer from definitional ambiguity within the academe. In Chapter 3, a review of efforts to provide direction and structure to the science reveals a continuum of approaches anchored at either end by differing visions of how the science interfaces with practice (solutions). At one end, basic science of societally defined problems informs decisions about possible solutions and their application. At the other end, applied research directly affects the options available to decision makers. While clear from the literature, survey data further suggests that the dichotomy does not appear to be as apparent in the minds of practitioners. </p><p>In Chapter 4, the UHI is first addressed at the synoptic, mesoscale. Urban climate is the most immediate manifestation of the warming global climate for the majority of people on earth. Nearly half of those people live in small to medium sized cities, an understudied scale in urban climate research. Widespread characterization would be useful to decision makers in planning and design. Using a multi-method approach, the mesoscale UHI in the study region is characterized and the secular trend over the last sixty years evaluated. Under isolated ideal conditions the findings indicate a UHI of 5.3 ± 0.97 °C to be present in the study area, the magnitude of which is growing over time. </p><p>Although urban heat islands (UHI) are well studied, there remain no panaceas for local scale mitigation and adaptation methods, therefore continued attention to characterization of the phenomenon in urban centers of different scales around the globe is required. In Chapter 5, a local scale analysis of the canopy layer and surface UHI in a medium sized city in North Carolina, USA is conducted using multiple methods including stationary urban sensors, mobile transects and remote sensing. Focusing on the ideal conditions for UHI development during an anticyclonic summer heat event, the study observes a range of UHI intensity depending on the method of observation: 8.7 °C from the stationary urban sensors; 6.9 °C from mobile transects; and, 2.2 °C from remote sensing. Additional attention is paid to the diurnal dynamics of the UHI and its correlation with vegetation indices, dewpoint and albedo. Evapotranspiration is shown to drive dynamics in the study region.</p><p>Finally, recognizing that a bridge must be established between the physical science community studying the Urban Heat Island (UHI) effect, and the planning community and decision makers implementing urban form and development policies, Chapter 6 evaluates multiple urban form characterization methods. Methods evaluated include local climate zones (LCZ), national land cover database (NCLD) classes and urban cluster analysis (UCA) to determine their utility in describing the distribution of the UHI based on three standard observation types 1) fixed urban temperature sensors, 2) mobile transects and, 3) remote sensing. Bivariate, regression and ANOVA tests are used to conduct the analyses. Findings indicate that the NLCD classes are best correlated to the UHI intensity and distribution in the study area. Further, while the UCA method is not useful directly, the variables included in the method are predictive based on regression analysis so the potential for better model design exists. Land cover variables including albedo, impervious surface fraction and pervious surface fraction are found to dominate the distribution of the UHI in the study area regardless of observation method. </p><p>Chapter 7 provides a summary of findings, and offers a brief analysis of their implications for both the scientific discourse generally, and the study area specifically. In general, the work undertaken does not achieve the full ambition of sustainability science, additional work is required to translate findings to practice and more fully evaluate adoption. The implications for planning and development in the local region are addressed in the context of a major light-rail infrastructure project including several systems level considerations like human health and development. Finally, several avenues for future work are outlined. Within the theoretical development of sustainability science, these pathways include more robust evaluations of the theoretical and actual practice. Within the UHI context, these include development of an integrated urban form characterization model, application of study methodology in other geographic areas and at different scales, and use of novel experimental methods including distributed sensor networks and citizen science.</p> / Dissertation

As urbanization and industrialization progressed during the last decades, Urban Heat Island (UHI) has become a major environmental issue to many cities around the world. The effect of UHI differs from area to area due to varying urban scale, population density, construction of urban surface layer, the level of industrialization and type of climate. Researchers have made great efforts in investigating various approaches to Urban Heat Island studies. Monitoring technologies have been widely used in this field, especially Geographic Information System (GIS) and remote sensing technology. Computational Fluid Dynamics (CFD) simulations are also actively applied in wind engineering, which can provide details of air flow over urban areas. The combined application of these technologies can provide the monitoring and simulation of urban wind corridor and thermal environment that can produce relevant information at a lesser time.A research using GIS, remote sensing technology and CFD simulation was done in this project to obtain a holistic view of the urban thermal environment and wind flow for Gävle City. With GIS and remote sensing the thermal image of the city was presented. The temperature data, which were collected from MODIS satellite were transferred and processed by ArcGIS and Global Mapper. The wind flow above the city was simulated through constructing geometric and mathematical model with OpenFOAM. The outcomes of the modeling and simulation identified that the temperature in the city center could possibly reach 35℃ during summers, which can cause the Urban Heat Island to form. Ventilation was also poorer in the city centre, and neither the river nor the green area in the southwest could help ventilate the city. The study result also suggested that certain sites in the city had relatively high wind flow for urban wind turbines to work.This study had used method of Urban Heat Island study with remote sensing and CFD technologies. The model produced from simulation could also be used to further study Gävle city's thermal and wind environment to produce more accurate results.

As modificações impostas pela ação do homem desequilibram o complexo sistema natural, alterando os elementos e características do clima na escala local. A cidade é o exemplo mais significativo destas transformações e o campo térmico urbano é um dos elementos do sistema cidade-atmosfera mais afetados pela mudança do uso e da cobertura do solo. No Brasil, tem-se observado que a grande maioria dos estudos de clima urbano está focada nas grandes cidades, sobre as características do clima urbano para a região Centro-Oeste, especialmente nas cidades de pequeno porte, pouco se conhece. Dessa forma, o objetivo desta pesquisa foi de analisar as influências das características geourbanas na configuração do clima da cidade de Iporá e identificar a variabilidade temporal e espacial das ilhas de calor urbanas. Para tanto, instalou-se oito aparelhos termo-higrômetros para a coleta de dados de temperatura do ar e umidade e duas estação meteorológicas completas, uma na área urbana e a outra na área rural, também foram utilizadas imagens multiespectrais do satélite Landsat 5 e 8. Nas análises dos dados foram utilizadas regressões lineares simples e múltiplas, modelagem, simulações e foi proposto um índice (InGe) para quantificar a influência do homem no clima da cidade. Os resultados evidenciaram que: 1 - em algumas áreas da cidade de Iporá foram observadas tendências significativas de aumento na intensidade das anomalias térmicas; 2 - as variáveis mais influentes na regressão linear múltipla da temperatura de superfície (TS) foram o NDVI que explicou 35% da variabilidade e a densidade demográfica com 25%; 3 - a equação final, proposta como modelo preditor da intensidade máxima da ilha de calor urbana de superfície para a Região do Oeste Goiano obteve r2 de 0,6; 4 - quanto maior a distância da área verde maior a temperatura de superfície, além disso, na primavera ou próximo dela, a intensidade do efeito da área verde na TS foi muito superior ao efeito em outras datas; 5 - os padrões dos desvios da umidade absoluta permitiram afirmar que a área central, mais urbanizada, teve os maiores desvios negativos e áreas com maiores valores de NDVI e próximas aos cursos d\'água apresentaram os maiores desvios positivos de umidade; 6 - as ilhas de calor urbanas em Iporá foram mais frequentes na intensidade de 0,5°C e 1°C, a intensidade máxima observada foi de 3,5°C; 7 - as áreas localizadas nos fundos de vale apresentaram os menores valores térmicos, o que sugere uma drenagem de ar frio. Contudo, constatou-se que a cidade de Iporá, mesmo se tratando de uma cidade pequena, modifica seus parâmetros atmosféricos. / The changes imposed by man unbalance the complex natural system, changing the climate elements and features at local scale. The city is the most significant example of these transformations and the urban thermal field is the element of the city-atmosphere most affected by the use and land cover change system. In Brazil, it has been observed that the vast majority of urban climate research is focused on big cities, so that little is known on urban climate characteristics for the Midwest, especially in small towns. Thus, the objective of this research was to analyze the influence of Geourban characteristics in the climate setting of the city of Iporá and to identify the temporal and spatial variability of urban heat islands. Therefore, eight Thermo-Hygrometer devices for collecting air temperature and humidity data and two complete weather stations were settled, one in the urban area and the other in the rural area; Landsat 5 and 8 multi-spectral images of were also used. In data analysis simple and multiple linear regressions, modeling and simulations were used and an index (InGe) was proposed to quantify the man influence on the city climate. The results showed that: 1 - in some areas of Iporá city significant trends of increasing intensity of thermal anomalies were observed; 2 - the most influential variables in the multiple regression of surface temperature (TS) were explained by NDVI (35% of the variability) and population density (25%); 3 - the final equation, proposed as a maximum intensity predictive model of the urban surface heat island for the West Region of Goiás, we obtained an R2 0.6; 4 - the greater the distance from the green area, the higher surface temperature; moreover, in the spring, or close to it, the intensity of the green area effect on TS was by far superior to the effect at other periods; 5 - the patterns of the absolute humidity deviations allow us to affirm that the central area, urbanized, had the highest negative variances, while the areas with higher NDVI values and nearby watercourses showed the highest positive deviations moisture; 6 - urban heat islands on Iporá were more frequent at the intensity of 0.5°C to 1°C, while the maximum intensity was observed at 3.5°C; 7 - the areas located in the valley bottoms had the lowest thermal values, suggesting a cold air drainage. However, it was found that the city of Iporá, despite being a small town, modifies its atmospheric parameters.

Eventos de brisa marítima (BM) são comuns na Região Metropolitana de São Paulo (RMSP). No verão, em particular, estão associados com tempestades, chuvas, rajadas de vento, granizo e descargas atmosféricas intensas na RMSP. Utilizou-se o método de OLIVEIRA e SILVA DIAS (1982) para identificar os eventos de BM. Todos os eventos de BM entre 2005 e 2008 foram analisados por meio de medições de superfície, altitude, radares meteorológicos, satélite e modelagem numérica da atmosfera. Em geral, a penetração da frente de BM na RMSP ocorre entre o meio e o fim da tarde com aumento da temperatura do ponto de orvalho. Ainda, o ambiente urbano mais aquecido tende a intensificar as tempestades que podem produzir enchentes, alagamentos, queda de árvores, entre outros impactos socioeconômicos muito significativos. A partição anual pluviométrica devido a BM foi estimado com o radar meteorológico de São Paulo. Os resultados indicam um núcleo de máxima precipitação acumulada com pico de 600 mm sobre a RMSP, muito maior que no entorno dessa. A modelagem com o ARPS permitiu simular condições médias espaciais em baixos, médios e altos níveis de diversas variáveis dos eventos analisados. As simulações de controle e específicas com ARPS sugerem um impacto significativo da cobertura do solo na distribuição espacial da precipitação. As análises foram complementadas com medições do radar meteorológico MXPOL e demonstram a importância desse tipo de sensoriamento remoto na detecção e previsão a curtíssimo prazo da penetração de BM, com alta resolução espaço-temporal. / Sea breeze events (SB) are common in Metropolitan area at São Paulo (MASP). Particularly, in the summer, SB triggers over MASP deep convection, heavy rainfall, wind gusts, hail and lightning. OLIVEIRA and SILVA DIAS (1982) method was used to identify the SB events. SB events between 2005 and 2008 were analysed by means of surface and upper air measurements, weather radar, satellite and numerical modelling. In general, the SB front penetrates in MASP between midafternoon and evening increasing dew point. Moreover, the warmer urban environment tends to intensify storms that produce flooding, falling trees, among other large socioeconomic impacts. The annual rainfall partition due to SB was estimated using the São Paulo weather radar. The results indicate a core of maximum rainfall accumulation of 600 mm over MASP, much larger than that in the vicinity. The modelling with ARPS allowed simulate conditions spatial average in low, medium and upper levels of several variables of the analysed events. Moreover, the ARPS system was used to simulate SB with control and specific runs. Results suggest significant impact of surface cover on rainfall distribution. MXPOL weather radar measurements of SB were important in detecting and nowcasting SB inflow at very high spatial and temporal resolution.