Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Urban heat island effect on building energy consumption : A case study using thermal load calculation tool

Şehir ısı adası etkisinin binalarda enerji tüketimine etkisi : Isıl yük hesaplama programı kullanılarak yapılan örnek bir çalışma

Auteur : LEBLEBİCİ Mustafa

Université de soutenance : İstanbul Teknik Üniversitesi

Grade : Master Science Thesis 2020

Résumé partiel
Urbanization increases human comfort and quality of living by altering ground canopy layer. Building façades, roads, pavements, roofs and other urban materials are parts of urban formation. 21st century has seen a rapid urbanization. Conflicts, better life expectancy and lack of resources in rural areas have drawn people into the large cities. Rapidly increasing population in the cities paved the way to the increased anthropogenic formation on the ground canopy layer and the release of the anthropogenic heat. Urban formation differs from its surrounding rural areas by having different material, shape and geometry. Altered air flow throughout the city and reduced sky-view factor because of the urban design, increased solar absorption because of the urban material combined with the lack of green areas led to the increased ambient temperatures in the urban areas. This heat content is called as Urban Heat Island which damages thermal balance of cities. Coupled with Climate Change, UHI Effect induces lots of problems. Tackling the temperature increase caused by anthropogenic formation, solar and infrared heating requires additional cooling which causes additional anthropogenic heat release. In return, it also causes temperature increase as in vicious circle ; solution to the problem increases severity of the problem. Factors that form UHI could be listed as sky view factor, urban design and material, urban ventilation (air flow) and urban albedo. Mitigation strategies of UHI could be listed as, cool urban materials, super-cool materials, urban ventilation, urban greening and reflective/retro-reflective materials. Aim of the thesis is to show dynamics of urban formation and its relation with the surrounding rural areas by explaining factors, variables that form UHI and related mitigation strategies in order to build a ground and related common language for those who wants to study and research UHI which requires extensive multi-disciplinary contribution. Tools used while studying UHI could be listed as ; numerical modelling, field measurements and satellite sensors. Hot Climates that require cooling more than heating are especially vulnerable to UHI effect which increases urban temperature, mortality rates, cooling loads, peak and total electricity demand, causing air pollution and decreasing environmental comfort and public health Both urban and rural areas receive the same solar radiation from the sun. Albedo meaning fraction of incident radiation reflected by a body or surface determines the amount of short-wave solar radiation absorbed. Due to the low albedo values, short-wave solar radiation is absorbed by the urban materials. Absorbed solar radiation is then re-radiated to the urban area with a longer wave-length thus causing infrared heating. Anthropogenic heat is the heat content that is released as waste heat from buildings (HVAC Equipment), transportation systems(vehicles) and power plants. Anthropogenic Heat (AH) and moisture enter urban area simultaneously as it is generated and causes temperature increase. Using cool materials for urban formation that absorb less (high reflectance) and emit more (high thermal emittance) helps to keep surface temperatures low.

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