Lucila Chebel Labaki

Thermal bioclimate in idealized urban street canyons in Campinas, Brazil

Among several urban design parameters, the height-to-width ratio (H/W) and orientation are important parameters strongly affecting thermal conditions in cities. This paper quantifies changes in thermal comfort due to typical urban canyon configurations in Campinas, Brazil, and presents urban guidelines concerning H/W ratios and green spaces to adapt urban climate change. The study focuses on thermal comfort issues of humans in urban areas and performs evaluation in terms of physiologically equivalent temperature (PET), based on long-term data. Meteorological data of air temperature, relative humidity, wind speed and solar radiation over a 7-year period (2003–2010) were used. A 3D street canyon model was designed with RayMan Pro software to simulate the influence of urban configuration on urban thermal climate. The following configurations and setups were used. The model canyon was 500xa0m in length, with widths 9, 21, and 44xa0m. Its height varied in steps of 2.5xa0m, from 5 to 40xa0m. The canyon could be rotated in steps of 15°. The results show that urban design parameters such as width, height, and orientation modify thermal conditions within street canyons. A northeast–southwest orientation can reduce PET during daytime more than other scenarios. Forestry management and green areas are recommended to promote shade on pedestrian areas and on façades, and to improve bioclimate thermal stress, in particular for H/W ratio less than 0.5. The method and results can be applied by architects and urban planners interested in developing responsive guidelines for urban climate issues.

Bioclimatic and vernacular design in urban settlements of Brazil

Abstract Brazilian regional traditional architectural features are analyzed, especially with regard to the new emerging vernacular of self-built urban settlements. Bioclimatic design is discussed as to its scientific and technical features with respect to the subtropical climate of the city of Campinas in the State of Sao Paulo, Brazil. The main goal of this work is to analyze a specific self-building house phenomenon and its response to climate. From this analysis thermal comfort should be addressed in terms of correct architectural elements. An appropriate new architecture for the urban poor should be based on bioclimatic design principles and the positive elements of the new urban vernacular.

Formation of magnetite from non-crystalline iron(III) hydroxoacetate

Abstract A simple and convenient procedure for the synthesis of magnetite by heating iron(III) hydroxoacetate at temperatures above 250 °C under nitrogen is reported. The reaction product was characterized by X-ray diffraction, surface area determination and chemical analysis. On heating, the amorphous hydroxoacetate loses hydroxyl and acetate groups, as observed in the infrared spectra; evolved ammonia, carbon dioxide, acetone and acetic acid were identified; iron(II) formation in the hydroxoacetate is slow below 250°C but its rate increases with increasing temperature. At 382°C the iron(II) content in the product is 22.5% and the total iron content is 72.1%.

The impact of different cooling strategies on urban air temperatures: the cases of Campinas, Brazil and Mendoza, Argentina

This paper describes different ways of reducing urban air temperature and their results in two cities: Campinas, Brazil—a warm temperate climate with a dry winter and hot summer (Cwa), and Mendoza, Argentina—a desert climate with cold steppe (BWk). A high-resolution microclimate modeling system—ENVI-met 3.1—was used to evaluate the thermal performance of an urban canyon in each city. A total of 18 scenarios were simulated including changes in the surface albedo, vegetation percentage, and the H/W aspect ratio of the urban canyons. These results revealed the same trend in behavior for each of the combinations of strategies evaluated in both cities. Nevertheless, these strategies produce a greater temperature reduction in the warm temperate climate (Cwa). Increasing the vegetation percentage reduces air temperatures and mean radiant temperatures in all scenarios. In addition, there is a greater decrease of urban temperature with the vegetation increase when the H/W aspect ratio is lower. Also, applying low albedo on vertical surfaces and high albedo on horizontal surfaces is successful in reducing air temperatures without raising the mean radiant temperature. The best combination of strategies—60xa0% of vegetation, low albedos on walls and high albedos on pavements and roofs, and 1.5 H/W—could reduce air temperatures up to 6.4xa0°C in Campinas and 3.5xa0°C in Mendoza.

Thermal bioclimate as a factor in urban and architectural planning in tropical climates—The case of Campinas, Brazil

Urban climate studies can provide information necessary for the improvement of conditions of thermal comfort for people in cities in the Tropics. This paper presents thermal bioclimate analysis of a case study in Campinas, Brazil, using air temperature (Ta), mean radiant temperature (Tmrt), and Physiologically Equivalent Temperature (PET), which can be used as assessment factors for urban and architectural planning in tropical climate. The meteorological data air temperature, relative humidity, wind speed, and solar radiation for the period 2003 to 2010 were used to calculate Tmrt and PET using the RayMan Pro model. Simulations of shade and wind speed variations were performed to quantify changes in thermal bioclimate due to modifications in urban morphology. The results show that solar radiation and wind speed not only influence air temperature, but also more extensive thermal comfort and heat stress as well. Furthermore, the simulations of the variation of wind speed and shade conditions demonstrate that shade can improve thermal comfort situations in terms of PET above 35xa0°C. The improvement of outdoor thermal comfort is an important step in achieving sustainability of urban spaces and configurations. These results are valuable for architects, planners, and urban designers for the description of conditions and the development of possibilities for improving microclimatic conditions based on urban design and configurations.

Conforto térmico propiciado por algumas espécies arbóreas: avaliação do raio de influência através de diferentes índices de conforto

The thermoregulatory characteristics of trees can be used effectively when there is knowledge available about the thermal comfort provided by an individual isolated tree in its radius of influence. Several thermal comfort indices have been used, but only a few of them are actually adapted to the Brazilian reality. The aim of this study is to compare results using three thermal comfort indices in outdoor environments - the Tridimensional Bioclimatic Chart, and the PET and PMV indices to evaluate the performance of three different species in the urban microclimate: Ipe-Amarelo, Jambolao and Mangueira. The research was divided into three stages: (a) selection of appropriate measurement sites and individual trees; (b) collection of environmental parameters: solar radiation, air and globe temperatures, relative humidity and wind speed; (c) comparison of the results obtained for the three indices through the parameter Comfort Hours Unit. The results show that the thermal comfort provided by species throughout the year regardless of the thermal comfort index used in the analysis depends on the canopy architecture. Ipe-amarelo is the species that provides the best thermal comfort sensation, while perennial species like Jambolao and Mangueira influence the thermal sensation in the near surroundings more strongly in summer than in winter, with more comfortable conditions in the shadow of the tree canopy.

Phase characterization of Fe17Nd2Nx samples with different nitrogen contents

Abstract Samples of Fe 17 Nd 2 N x have been prepared for x =0.0, 0.5, 1.0, 1.5, 2.0 and 2.1 nitrogen atoms per formula unit, at 400 °C. They were analysed by metallography, thermomagnetic analysis, electron microprobe and X-ray diffraction. The measurements showed that all the samples contained the phase Fe 17 Nd 2 , free of nitrogen, together with the Fe 17 Nd 2 N 2.3 saturated phase.

Diffusion patterns of formation of the phase Fe17Nd2Nx at 400°C

Abstract Samples of Fe 17 Nd 2 N x have been prepared for x =0.0, 0.5, 1.0, 1.5, 2.0 and 2.1 nitrogen atoms per formula unit, at 400°C. They were analysed by metallography, thermomagnetic analysis, electron microprobe and X-ray diffraction. The measurements show that all the samples contained the pure Fe 17 Nd 2 phase alongside the saturated Fe 17 Nd 2 N 2.3 phase. The measurements also show that the diffusion mainly proceeds along extended defects as grain and phase boundaries, dislocations and dislocations arrays. The expected shell-core diffusion model is not observed. Heavily nitrided samples shows the presence of striae depicting fast diffusion paths from the exterior to the interior of the powder particles.

Vamos passear na floresta! O conforto térmico em fragmentos florestais urbanos

This study investigated the role of urban forest fragments in thermal comfort. For that purpose, five different locations in the city of Campinas (Brazil) were monitored during the summer, autumn and winter of 2009. Microclimatic data were obtained with the use of a portable weather station that measured air temperature, air humidity, radiation, wind speed and globe temperature. In addition, structured interviews and field observations were carried out to evaluate the thermal comfort conditions and the occupants’ perceptions of their environment. The PMV and PET indices were calculated by the RayMan 1.2 software and compared with the actual votes obtained through the interviews. The results indicate that urban forest fragments improve thermal comfort. The percentage of subjects reported as thermally neutral varied between indices: 72.4% were found comfortable, 63.3% were in the PET limit of 18-23 o C, and 39,8% were in the PMV range of -0.5 to +0.5. Occupants perceived those places as comfortable, linking this to nature, but they also observed some problems regarding conservation and occupation. The specific forest microclimate, fresh air, and the perception of clean air were also cited by the population and can be linked to environmental comfort.

A house design assistance program for the self-building process of the region of Campinas, Brazil: Evaluation through a case study

Abstract This paper evaluates a technical assistance program for house self-builders in the region of the city of Campinas, Brazil. The assistance given is in the form of an individualized house design, distributed to self-builders, based on an automated computer aided design (CAD) generated design method. A case study is used to demonstrate the efficacy of the assistance program. The transfer process of a population from an environmental protection area to a new location and their need for rapid house construction is the specific case presented. Houses are evaluated as to satisfaction and environmental comfort conditions. As a result, lessons are learnt about assistance programs and their success in improving housing quality.