ENVI-met

The Local Climate Zone (LCZ) classification system encompasses climate-critical urban parameters (such as land cover, land use and urban morphology) in its definition. A sensitivity analysis of geometric and surface cover characteristics, could allow an in-depth understanding of which parameters are critical to climate sensitive urban spaces in the warm humid tropics. In this work we examine the sensitivity of these variables to local warming in Colombo, Sri Lanka. Mean Radiant Temperature (MRT) – a key variable in outdoor thermal comfort at street level – is linked to urban indicators in the LCZ classification, together with climate variables generated by the microclimate simulation model ENVI-met. The simulations include a series of LCZ-based morphology options to reduce MRT in the urban outdoors at present and in a future climate change scenario. Statistical analysis of results show stronger relationships with geometric and surface cover variables in the globally warmed background scenario, while the geometric variables are more important to local warming than surface cover variables. The sky view factor (SVF) showed the strongest relationship to MRT. Based on these results the work presents ways in which the utilisation of geometric and surface cover parameters could enhance planning and policy for a climate sensitive city.

Salcedo Village is a part of the Central Business District of Makati City. Pereira & Lopez (2004) and Tiangco, et al. (2008) in their respective journals have identified this area as one of the hot spots in Metro Manila, Philippines. This study aims to propose an urban retrofit design that mitigates the heat stress in the area.
The simulation tool identified as the most feasible to conduct this investigation is ENVI-met v3.1. However, since both the researchers have different study context (scale, time period, and methodology) with this investigation, the urban heat island (UHI) and temperature they have identified cannot be simply adapted. This study therefore quantifies its own UHI (without anthropogenic heat) by comparing Salcedo Village’s 2005 and 1995 air temperature. Over the last 10years, the area has been affected by its urbanization and accumulating heat. It has been observed, as was also supported by other sources, that UHI is more intense during the nighttime of winter season; hence the study focuses on mitigation of the heat stress during this period. The estimated heat stress becomes the target degree mitigation, and is used to objectively assess the effectiveness of the retrofit proposal.
The proposal is based from the deductive investigation of the effectiveness of a collection of strategies, which are academically proven that can adverse the effect of UHI. This study tests these strategies in this particular location and quantifies according to their effectiveness in the degree heat mitigated (temperature) and total area affected.
It is concluded that the most effective strategy is planting trees with high leaf area density (LAD); followed by the increase in vegetated area, and the provision of shades from trees. Observations on the wind behavior was also made and apllied together with these strategies in Salcedo Village. The urban retrofit proposed is able to mitigated 0.5-1°C over 94% of the area.

Rapid urbanization in Phoenix, Arizona has increased
the nighttime temperature by 5°C, and the average daily temperatures by 3.1°C. The energy balance of urban surface paving materials is the main contributor to the phenomenon of the Urban Heat Island effect (UHI). Much of the literature dealing with mitigating UHI effects recommends extensive tree planting as the chief strategy for reducing the UHI. However, while the extensive tree canopy is beneficial in providing
daytime shade for pedestrians, it may reduce the pavement surfaces’ sky-view factor during the night, thereby reducing the rate of nighttime radiation to the sky. From a UHI mitigation perspective, it may be more beneficial to use low height vegetation that does not reduce the sky view factor as large shade trees would, increasing the urban surfaces’ nighttime
radiation potential. This paper proposes to use field data and simulation scenarios to optimize the use of vegetation for both improving daytime pedestrian thermal comfort as well as enhancing nighttime radiation. The CFD microscale and mesoscale urban scenarios simulation results can potentially give urban planners and architects insights on improving their
recommendations for implementing landscape design
strategies for optimal effect on both the pedestrian scale and larger urban forms.

فى إطار البحث الحالى، فإن نموذج ENVI- met  هو نموذج لمحاكاة المناخ التفصيلى فى نطاق المساحات الصغيرة والذى يعطى أفضل النتائج لتقييم العناصر المناخية والبيئية فى المناطق الحضرية
      وفى هذه الدراسة يتم تقييم لنموذج من حيث كفاءة النتائج لدراسة موضوع الاحتباس الحرارى بجزيرتى الدهب والقرصاية والتى تم تحديد اثنين من السيناريوهات لعامى 2016، 2030  سنة الهدف لتنمية المستدمة لمصر والأمم المتحدة وتمثل يوم فى فصل الصيف للمحاكاة وتقييم النموذج بعتبر ذلك الفصل الأعلى حرارة وهذا العنصر من أهم العناصر المناخية المؤثرة فى الأنشطة البشرية
      وهدف هذه الدراسة هو تقييم النموذج وكيفية تحديد استراتيجيات للتخفيف والتكيف من خلال نتائج محاكاة النموذج وبالتالى تحديد متطلبات المكان بشكل أكثر دقة فى المعالجات المناخية، إلى جانب ذلك تعد انتقال منطقة الدارسة من محمية طبيعية إلى إدارة بيئية بمثابة اهدار للأراضى الزراعية الموجود بهذه الجزر وعدم مراعاة البعد الإجتماعى والأقتصادى وتغير نشاط السكان الحالى وهو نشاط زراعي ونقلهم إلى الإسكان الإجتماعى دون النظر لهذه الفئة من السكان حيث أن مشروعات التنمية يجب أن تكون فى نطاق مراعاة امكانيات المكان ويعتبر النموذج ذو كفاءة دقيقة وعالية جدا ولكن يحدث بعض القصور نتيجة لطبيعية كل منطقة مثلا : كوبرى دائرى المنيب بجزيرة الدهب  إلى جانب نقص فى بعض البيانات كمواد البناء، التربة....... إلخ وهذا القصور خاص بالبيئية المصرية.  وشملت عملية تقييم النموذج أهم المعايير التالية:  مساحة المنطقة –  الرياح –  الرطوبة –  درجة حرارة الهواء –  الملوثات وجودة الهواء –  درجة حرارة سطح التربة –  نسبة المياه بالغطاء النباتى  – المحتوى المائى  – المسطحات المائية –  شكل النبات –  التمثيل الضوئى للنبات  – درجة حرارة أوراق الشجر  – تأثير النباتات على المناخ المحلى –  شكل المبنى –  مواد البناء  – درجة الحرارة فى الأماكن المغلقة (طاقة المبنى)  – الأسطح الخضراء.  يعتبر النموذج  ذو دقه عالية فى أكثر من معيار، إلى جانب إختلاف ذلك على حساب طبيعية  بعض المناطق
الكلمات المفتاحية :  ENVI-met- جزيرة القرصاية –  جزيرة الدهب -  التكيف - التخفيف

In the search for a way to reduce greenhouse gas emissions, considerable attention is paid to the alternative energy sources. One of the most promising solution is considered to be the massive use of photovoltatic elements. In countries with large free from economic use territories, PVP can be used in the format of "solar power plants". In urban areas the prospects for PVP are associated with integration into the outer shells of buildings and structures. However, the use of PVP has a complex of negative consequences for the environmental characteristics of the human environment. In particular, due to a decrease in albedo, PVP increase the amount of absorbed solar radiation and increase the temperature of the environment at their location. The article deals with the bioclimatic aspect of the massive application of PVP in an urbanized area on the example of Moscow. It is shown that this can lead to a significant increase in urban heat island and deterioration of bioclimatic comfort to overheating values, critical for humans.

Rapid urbanization in Phoenix, Arizona has increased the nighttime temperature by 5°C (9 °F), and the average daily temperatures by 3.1°C (5.6 °F) (Baker et al 2002). On the macro scale, the energy balance of urban surface paving materials is the main contributor to the phenomenon of the Urban Heat Island effect (UHI). On the micro scale, it results in a negative effect on the pedestrian thermal comfort environment. In their efforts to revitalize Downtown Phoenix, pedestrian thermal comfort improvements became one of the main aims for City planners. There has been an effort in reformulating City zoning standards and building codes with the goal of developing a pedestrian friendly civic environment. Much of the literature dealing with mitigating UHI effects recommends extensive tree planting as the chief strategy for reducing the UHI and improving outdoor human thermal comfort. On the pedestrian scale, vegetation plays a significant role in modifying the microclimate by providing sha...

Two major forces that are shaping our cities today are the population growth and the rising rates of urbanization. For many reasons, one of the current needs of urban settlements is a higher urban density, giving priority to the existing city, a topic that still causes some debate. Assuming that the densification is inevitable and desirable from the point of view of urban sustainability, the subject of this research is the effect of built density on urban microclimate in Sao Paulo, Brazil. Sao Paulo is characterized by a heterogeneous urban structure, which has been caused by the rapid growth of the city during the 20th century. The city has an average population density around 74 inhabitants/ha. Since higher values of population density around 250 inhabitants/ha and lower values around 100 inhabitants/ha can be found not only in peripheral districts but also in in high-rise central districts, previous local research demonstrate that extensive verticalization and a certain building ...