1,721,050 research outputs found
Development, testing and evaluation of energy savings potentials of photovoltachromic windows in office buildings. A perspective study for Australian climates
No full textPhotoVoltaChromic (PVC) cells are among the emerging smart windows technologies with an interesting potential of building integration. PVC technology combines ElectroChromic materials with Dye Sensitized Solar cells in order to have a self-powered adaptive transparent film. The main advantage of this technology is to have an automatic control – potentially manually overridden – of colouration process, depending on levels of solar irradiance. Moreover, a PVC window can operate, at the same time, as a photovoltaic cell, producing energy exceeding the amount required for the colouring process. In the current study, for the first time, the full potential of PVC windows in office buildings is assessed. For this analysis, a PVC cell with a Visible Light Transmittance (VLT) variable between 16.9% and 31.5% has been selected. Australia has been considered as reference location, due to the presence, in its territory, of different climatic regions, ranging from tropical/subtropical climates to the temperate ones. The results show a strong dependence of potential energy savings on Window-to-Wall Ratio (WWR) and solar irradiance on windows. In cooling dominated climates, the adoption of PVC windows has been demonstrated to be always beneficial, even with very low WWR and/or non-optimal exposures, achieving overall energy savings of up to 20%. In heating dominated climates, adoption of PVC windows should be carefully considered, as it is highly beneficial when large glazed surfaces are present. In this case annual total energy savings up to the 32% can be predicted in comparison with buildings equipped with standard clear windows
Investigating the effects of the greenery increase on air temperature, ventilation and cooling energy demand in Melbourne with the weather research and forecasting model and local climate zones
Full text linkVegetation has a well-known potential for mitigating urban overheating. This work aims to explore the effects of enhancing urban greenery in Melbourne (Australia) through a configuration of the Weather Research and Forecasting (WRF) model including the Building Effect Parameterization and the Local Climate Zones and presents novelties in: i) covering two-months and ii) focusing on air circulation and buildings cooling energy demand through the ventilation coefficient (VC) and the cooling degree hours (CDHs). A control case and two "what-if" scenarios with a growing green coverage equal to 35 % (control case), 50 % (modest increase) and 60 % (robust increase) have been designed and then simulated for January and February 2019. Outcomes reveal a maximum drop in 2 m temperature of approximately 0.4 °C and 0.8 °C at 14:00 LT for the modest and robust green increase scenario, respectively. The urban-rural energy surplus for cooling buildings is reduced and even counterbalanced. Peak CDHs decrease from 143 °C·h of the control case to 135 °C·h (modest increase) and 126 °C·h (robust increase), while they measure 137 °C·h in the non-urban areas. Average wind speed increases by 0.8 m/s (equal to 22 % with respect to the control case). Furthermore, adding urban greenery has an unfavorable implication on VC (maximum reduction of 500 m2s-1) with a consequent deterioration of the transport and dispersion of pollutants. Middle- and high-density classes are touched more than low-density by the VC reduction. In addition, the benefits of enhancing urban greenery concern physiologically and psychologically the quality of life of the dwellers
On the effect of summer heatwaves and urban overheating on building thermal-energy performance in central Italy
No full textLocal climate phenomena impose a serious threat to the built environment. In particular, urban heat island and heatwaves can significantly affect buildings’ thermal-energy performance. The purpose of this study is to investigate summer hot periods and their impact on building thermal-energy behavior in an urban area in Italy. To this aim, the statistical analysis of the microclimate variation during monitored hot periods is performed by the analysis of local weather parameters collected from a dedicated meteorological station. Moreover, the numerical analysis of representative Italian residential buildings is carried out to determine the role of such phenomena on indoor thermal comfort and cooling energy requirements, by considering the consequences arising from heatwaves due to the indoor overheating stress. The analysis showed a strong negative correlation between temperature and relative humidity during extreme hot periods (∼−0.92). Positive correlation was noted between temperature and solar irradiance (∼0.62) and temperature and wind velocity (∼0.33). The southern winds registered in normal hot periods reduced the heat stress by cooling-down the south-facing urban surfaces. The numerical analysis demonstrated higher indoor temperature for insulated buildings, requiring more than three times the cooling requirement of traditional non-insulated buildings in extreme hot periods and exacerbating the occupants’ vulnerability
High Performance Technologies and the future of architectural design
Full text linkHigh Performance Technologies and the future of architectural desig
Retrospective analysis of the energy consumption of single-family dwellings in central Argentina. Retrofitting and adaptation to the climate change
Full text linkTwo different analyses of the energy behavior of dwellings in Santa Rosa city (36°27' S, 64° 27' W, 182 m above sea level), in central Argentina, are presented. Firstly, a retrospective analysis of the operating energy -electricity and gas- of 10 compact housing in a period of 50 years is presented. Periods with missing data were fulfilled through predictive statistical models. Then, a “case study” was used to study different retrofitting strategies and to make a prospective analysis for future weather conditions calculated through the CMIP5-Coupled Model Intercomparison Project-Phase 5. The results indicate that the addition of thermal insulation in walls and roofs is highly beneficial, but the increase of glazed areas seems to be counterproductive. The energy demands for 2010 and 2039, for both the conventional and the retrofitted dwelling, show a decrease in winter and an increase in summer. We conclude that it is necessary to revise the dimensions suggested for the glazed areas, in order to deal with present and future indoor overheating. This paper presents the integration of past, present and future, towards a better comprehension of the challenges to be faced in the next decades.Fil: Filippin, Maria Celina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ricard, Maria Florencia. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Flores Larsen, Silvana Elinor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; ArgentinaFil: Santamouris, Mattheos. University of Athens; Greci
Influence of personal control on thermal comfort: A psychological effect or just the “right” temperature?
No full textPersonal control of indoor environmental conditions has a positive effect on subjective thermal comfort. This has been demonstrated in various field and laboratory studies for both office buildings and long-distance transport. It is still an open question whether the perceived higher comfort was due to the belief of being in control or to the option to set the right temperature. The study was designed to examine this question in an experimental setting in a long-distance train serving as test facility. Winter conditions were simulated for 84 subjects in total who could use infrared panels and seat heating elements, respectively, to adjust their individually preferred temperature in addition to the centrally controlled air condition of the train. In a second experimental condition, the same heating elements were in operation but subjects were not able to control them. Instead, the individual settings of the previous condition had been restored for each subject and were administered again without the subjects’ awareness. Thus, both conditions were identical except for the level of personal control.
The personal control of heating elements versus the automated settings did not lead to any differences in the perception or evaluation of temperature, air draught or thermal satisfaction. Thus, the psychological effect of being in control was near zero. The "right" thermal settings appeared to be crucial, whether controlled by the subjects or by an external protocol
Effects of personal control for thermal comfort in long-distance trains
Full text linkAs a result of its low environmental impact the railway system is the prime candidate to enable domestic
and continental mass passenger mobility. One important aspect determining the attractiveness of rail
journeys is the thermal comfort that is provided in a passenger rail car. Newer approaches focusing on
the improvement of thermal comfort in passenger rail cars are based on the idea to employ personalized
comfort zones. It is generally assumed that individual control over indoor climate settings contributes to
the passengers’ thermal comfort. The studies presented here further examine this assumption by considering the concept ‘‘thermo-specific self-efficacy” (specSE) as psychological construct in the context of
thermal comfort in a railway car. Two studies with 11 human subject test runs including 172 subjects
in total were performed in a mock-up of a passenger rail car. Environmental climate conditions in the
mock-up were controlled and measured. It was found that specSE can be considered as a distinct construct and that it contributed substantially to the prediction of thermal comfort and climate satisfaction.
In addition, it moderated the effects of available and exercised control. The presented results expand
upon earlier findings for the concept of personal control and confirm the role of specSE for thermal comfort predictions
Positive energy schools with cool materials and passive strategies: scenarios and perspectives for the Brazilian context
Full text linkTese (doutorado)—Universidade de Brasília, Faculdade de Arquitetura e Urbanismo, Programa de Pós-Graduação em Arquitetura e Urbanismo, 2024.Edifícios padronizados replicáveis podem causar desconforto e aumento no uso de ar-condicionado atualmente e no futuro. Além disso, materiais super frios são soluções passivas eficazes para aprimorar o potencial de edifícios com energia positiva e sobrevivência passiva. Portanto, hipotetiza-se que seja possível alcançar energia positiva, conforto térmico, resiliência térmica e sobrevivência passiva em escolas públicas brasileiras padronizadas do FNDE, com fácil replicabilidade em oito zonas bioclimáticas, utilizando materiais frios, outras estratégias passivas e produção de energia local a partir de sistemas fotovoltaicos. Portanto, esta tese é estruturada pelos seguintes objetivos específicos e métodos: identificar o desempenho termoenergético das atuais escolas públicas brasileiras padronizadas em oito zonas bioclimáticas por meio de simulações do DesignBuilder e análise de conforto térmico adaptativo da ASHRAE 55; verificar materiais frios adequados e estratégias passivas para alcançar conforto térmico por meio de simulações de otimização com o EnergyPlus e o algoritmo JEA, análise de sensibilidade e balanço térmico; avaliar a resiliência térmica e a sobrevivência passiva das escolas no presente e futuro (Ano Meteorológico Típico - TMY, 2050 e 2080) com indicadores de frequência, intensidade e severidade; e avaliar o alcance de um balanço energético positivo. Os resultados mostraram que os modelos escolares atuais carecem de conforto térmico. Assim, recomendam-se diferentes tipos de tintas frias: Termocrômicas para áreas dominadas por aquecimento; Espectralmente Seletivas para áreas secas dominadas por resfriamento e Alta Emissividade de Banda Larga para áreas úmidas dominadas por resfriamento extremo. Em relação ao envelope opaco, recomendam-se telhados planos de massa térmica e paredes isoladas. Em 7 das 8 zonas climáticas, a tinta fria sobre o telhado plano de massa térmica foi a estratégia passiva mais influente no conforto térmico, seguida pela ventilação natural. O modelo escolar otimizado garante conforto térmico e sobrevivência passiva em todas as zonas bioclimáticas em TMY sem ar-condicionado, alcançando facilmente um balanço energético positivo com o sistema fotovoltaico. Apesar dos resultados melhorados no conforto térmico e na autonomia passiva em todos os cenários, o modelo otimizado apresenta uma maior porcentagem de horas ocupadas em condições perigosas de calor. Consequentemente, é necessário o uso de condicionamento artificial e um aumento de até 18,75% no sistema fotovoltaico para garantir conforto térmico, sobrevivência passiva e energia positiva.Standardized replicable buildings can cause discomfort and increased air conditioning usage currently and in the future. Besides, supercool materials are effective passive cooling solutions to enhace the potential for positive energy buildings and passive survivability. Therefore, It is hypothesized that it is possible to achieve positive energy, adequate thermal comfort, thermal resilience and passive survivability in Brazilian standardized public schools of the FNDE with easy replicability in eight bioclimatic zones using cool materials, other passive strategies and local energy production from photovoltaic system. Hence, this thesis is structured by the following specific objectives and methods: identify thermoenergetic performance of current standardized brazilian public schools in 8 bioclimatic zones through DesignBuilder simulations and ASHRAE 55 adaptive thermal comfort analysis, verify suitable cool materials and passive strategies to achieve thermal comfort by optimization simulations with EnergyPlus and JEA Algorithm, sensitivity and heat balance analysis, evaluate the thermal resilience and passive survivability of the schools in present and future (Typical Meteorological Year – TMY, 2050 and 2080) with frequency, intensity and severity indicators and assess achieving a positive energy balance. Results showed that the current school models lack thermal comfort. Thus, different cool paints are recommended: Thermochromic for Heating-dominated; Spectrally Selective for Cooling-dominated dry and High Broadband Emissivity for Extreme-cooling-dominated humid zones. Regarding opaque envelope, thermal mass flat roofs and insulated walls are advised. In 7 out of the 8 climates, the cool paint on thermal mass flat roof was the most influential passive strategy on thermal comfort, followed by natural ventilation. The optimized school model ensures thermal comfort and passive survivability across all bioclimatic zones in TMY without artificial air conditioning, easily achieving a positive energy balance with PV system. Despite improved results in thermal comfort and passive autonomy in all scenarios, the optimized model exhibits higher percentage of occupied hours in dangerous heat. Consequently, artificial conditioning and a PV system increase of up to 18.75% are necessary to ensure thermal comfort, passive survivability and positive energy.Faculdade de Arquitetura e Urbanismo (FAU)Programa de Pós-Graduação em Arquitetura e Urbanism
Development of a holistic urban heat island evaluation methodology
No full textUrban Heat Island (UHI) phenomenon concerns the development of higher ambient temperatures in urban districts compared to the surrounding rural areas. Several studies investigated the influence of individual parameters in the UHI phenomenon, on the other hand, an exhaustive study that quantifies the influence of each parameter in the resulting UHI is missing in the related literature. This paper proposes a new index aimed at quantifying the hazard of the absolute maximum UHI intensity in urban districts during the Summer season by taking all the parameters influencing the phenomenon into account. In addition, for the first time, the influence of each parameter has been quantified. City albedo and the presence of greenery represent the most important characteristics with an influence of 29% and 21%. Population density, width of streets, canyon orientation and building height has a medium influence of 12%, 10%, 9% and 8% respectively. The remaining parameters have an overall influence of 11%. These results are achieved by exploiting three synergistically related techniques: the Analytic Hierarchy Processes to analyse the parameters involved in the UHI phenomenon; a state-of-the-art technique to acquire a large set of data; and an optimization procedure involving a involving a Jackknife resampling approach to calibrate the index by exploiting the effective UHI intensity measured in a total of 41 urban districts and 35 European Cities
- …
