Urban context and climate change impact on the thermal performance and ventilation of residential buildings: a case-study in Athens

Urban settings and climate change both impact energy use, thermal comfort and ventilation of buildings. This is more noticeable in hot urban areas where the urban heat island effect is more pronounced; also, in densely built urban areas where thermal comfort in naturally ventilated buildings is affected by changes in natural ventilation rates because of surrounding obstructions. In some cases, overshadowing might alleviate the impact.

Analyzing night time wind speed reduction effects from densification on predicted outdoor thermal comfort in a subtropical setting

The relationship between urban growth and the formation of urban heat islands, i.e. climatic differences between the urban area and adjacent rural areas, is discussed by several authors and is assumed to be ubiquitous for various climatic regions. Curitiba (25.5ºS), located within a region of subtropical climate in elevation, boasts a population growth rate of approximately 2% a year. The purpose of this study is to evaluate the effect of the urban agglomeration on microclimate changes.

Study of cooling system with water mist sprayers ―fundamental examination of particle size distribution and cooling effects

A cooling system spraying micro water droplets could prove useful in mitigating temperature increases in urban areas by using heat from water evaporation, a process that consumes only small amounts of water and energy. If water mist is sprayed in a semi-outdoor area, for example under a canopy, it could potentially improve conditions on hot days. However, there is little reference data concerning the design or control of such systems.

Estimating the impacts of climate change and urbanization on building performance

While the scientific literature is full of studies looking at the impact of climate change driven by human activity, there is very little research on the impact of climate change or urban heat island on building operation and performance across the world. For this study, typical and extreme meteorological weather data were created for 25 locations (20 climate regions) to represent a range of predicted climate change and heat island scenarios for building simulation. Then a set of prototypical buildings were created to represent typical, good, and low-energy practices around the world.

Creating weather files for climate change and urbanization impacts analysis

Over the past 15 years, much scientific work has been published on the potential human impacts on climates. For the Third Assessment Report published by the United Nations International Program on Climate Change in 2001, a series of economic development scenarios were created and four major general circulation models (GCM) were used to estimate the anthropogenesis-forced climate change. These GCMs produce worldwide grids of predicted monthly temperature, cloud, and precipitation deviations from the period of 1961-1990.

Study on the appropriate selection of urban heat island measure technologies to urban block properties

Toward the appropriate selection of urban heat island measures technology in the street canyon, the introduction effects of the technologies in the typical street canyon are analysed by the model calculation. It is appropriate to use street trees for the improvement of the thermal environment on the sidewalk and high reflectance paint or water-retentive pavement for the reduction of surface temperature on the roadway. Reduction of solar radiation gain to the sidewalk pavement surface is dependent on the location and area of the shadows by street tree.

Simultaneous integration of urban heat island mitigation technologies in the existing urban fabric in Athens, Greece

This research studies the possibility of introducing combinations of specific mitigation techniques for the urban heat island effect (UHI) in Athens, Greece. A variety of factors, such as surface cover, dense traffic, anthropogenic heat release and urban characteristics including geographic features and climate conditions interact with one another to create UHI, which is becoming increasingly evident also due to the changing climate, which in this region is expected to increase the duration of hot spells and the frequency of heat waves.

Urban gardens: as a solution to energy poverty and urban heat island

Urban gardens are a means of greening and are created by a local community. As regards any urban environment, urban greening helps cooling the air and provides shading, thus reducing building energy consumption and improving the outdoor conditions during the summer. In more detail, vegetation is a way to deal with the phenomenon of energy poverty in which many people cannot meet their basic energy needs as well as the phenomenon of urban heat island. This paper deals with the ways in which vegetation affects the improvement of microclimatic change, mainly through evapotranspiration.

The climate effects of increasing the albedo of roofs in a cold region

Urban heat island (UHI) phenomenon has been observed in many populated cities located in cold regions (e.g., Montreal in Canada) during summer. One of the well-known strategies to mitigate the temperature rise of urban areas is increasing their albedo. Roofs cover about 25% of urban areas and increasing their reflectivity would have significant effect on the total energy budget of a city. Changing the surface energy budget can directly affect the air temperature near ground and the vertical wind speed.

Green and cool roofs’ urban heat island mitigation potential in European climates for office buildings under free floating conditions

Heat island which is the most documented phenomenon of climatic change is related to the increase of urban temperatures compared to the suburban. Among the various urban heat island mitigation techniques, green and cool roofs are the most promising since they simultaneously contribute to buildings’ energy efficiency. The aim of the present paper is to study the mitigation potential of green and cool roofs by performing a comparative analysis under diverse boundary conditions defining their climatic, optical, thermal and hydrological conditions.