Validation of UWG and ENVI-Met Models in an Abu Dhabi District, Based on Site Measurements

Abstract

The city of Abu Dhabi is growing every year in population, urban extent and energy demand. This research focuses on the application of two simulation programs to estimate changes in urban climate associated with continued development in Abu Dhabi: The Urban Weather Generator (UWG) and ENVI-met. Simulation with these two software packages are validated with the site data measured in downtown Abu Dhabi. A comparison analysis (in the different seasons) between the rural data, the simulation output, and the site measurements shows the variations of the UHI in this Middle Eastern city and the potential of the validated tools. The main aims of this study are: (a) to make a seasonal validation of the UWG for the city of Abu Dhabi (referring to urban-rural available data). The tool was previously validated for a year (no seasonal division) for Abu Dhabi, Toulouse, Basel, Singapore, Rome and Barcelona. The simulations are based on the 2016 version of the Urban Weather Generator. The analysis is separated into three main seasons (instead of the full year): winter, spring, summer. (b) To make a seasonal validation and improve the second tool evaluated in this study, ENVI-met 4.0. The software can simulate urban temperature, humidity and wind speed. Guides are proposed for the enhancement of the accuracy of both estimation procedures. Referring to the results, UWG tends to overestimate the canyon temperature during the summer and has a more realistic estimation on the winter season. ENVI-met has better estimations of temperatures during the summer season compared to UWG. Finally, the UWG weather file contributes a more detailed energy model on a mesoscale model. It considers the seasonal effect and shows the impact of the climate on profiling the UHI phenomena. ENVI-met needs improvement in calculating the anthropogenic heat and in calculation of the mean radiant temperature. Sustainability 2019, 11, 4378 2 of 20districts. The latest study shows that the release of the anthropogenic heat creates an unstable layer in the lower level of the atmosphere-even during the night-compared to the countryside [2]. Therefore, including the anthropogenic heat, as a parameter in the simulations, is relevant for models prepared for the climate simulations [3,4].The urban microclimate is strongly connected to the anthropogenic heat released in the canyon. Cities with an efficient public transportation system and a central district cooling plant have a positive impact in improving the urban microclimate [5]. Annual average values show that cities such as Chicago (53 W/m 2 ), Montreal (99 W/m 2 ) and Budapest (43 W/m 2 ) have anthropogenic heat variation from 20 to 40 W/m 2 in summer, and from 70 to 210 W/m 2 in winter. The anthropogenic heat and the traffic schedule follow the same graphic distribution, having one peak in the morning and one peak in the evening [6].Abu Dhabi has developed rapidly over the past 60 years. During this time the urban settlement has grown from the main island towards the desert. The buildings located on the main ...

Thermal performance of the Urban Weather Generator model as a tool for planning sustainable urban development

“…These findings are coincident with investigations of Bande et al (2019) in Abu Dhabi, which showed that the UWG model tends to overestimate the canyon temperature during the summer and has a more realistic estimation in the winter season. Anyway, EN-VI-met has better estimations of temperatures during the summer season compared to the UWG.…”

Outdoor Thermal Comfort Study on a District Level as Part of the Housing Programs in Abu Dhabi and Al Ain, United Arab Emirates

“…The strategies are based on a combination of trees and shading structures applied in the walking paths or courtyards of the neighborhoods. The trees studied (applied in the simulation models) are local trees, and the shading devices refer to a structure analyzed in a previous study done for the OTC study of downtown Abu Dhabi [21]. The second step is taking site measurements for the boundary conditions of the CFD (Computational Fluid Dynamic) software used in this study.…”

“…The main factor that changes in these two districts is the relative humidity. Table 2 shows the different scenarios considered in this study [21]. The difference between the scenarios is mainly in the percentage of trees and shading devices used in order to understand the optimal proportion for an optimal PMV value at the specific season/day considered in this study.…”

“…The use of vegetation in the hot arid climate requires irrigation that is provided from the desalination process, a costly, time-consuming process. Shading structures combined with vegetation, trees grown in the local environment, is proven to be a sustainable approach to the urban spaces treatment and improving the microclimate [21,22].…”

Characterization of Local Climate Zones Using ENVI-met and Site Data in the City of Al-Ain, UAE

“…Mega cities like Dubai and Abu Dhabi have green standards in the urban planning sector and these are being extended to medium sized cities like Al Ain as well [15]. Implementation of such standards in urban planning or retrofitting existing infrastructure and buildings requires careful modelling of the local micro-climatic patterns [16]. In this study, the microclimate variation and UHI were assessed for Al Ain city using the LCZ mapping approach, while ENVImet was used to model each of the LCZ considered in the study.…”