PhD success for Yara Ayyad

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Dr Yara Ayyad

Congratulations to Yara Ayyad for being awarded her PhD thesis in October 2020. Yara’s thesis is entitled ‘Outdoor thermal comfort and airflow in relation to urban form in Amman, Jordan: a residential setting analysis’. Yara has now returned to Jordan, where she will resume her full-time academic career in the Faculty of Architecture and Design, Ahliyya Amman University.

The main aim of Yara’s research was to identify the key urban planning elements for enhancing the outdoor thermal comfort of pedestrians in a residential setting in the semi-arid climate of Amman in Jordan. The study followed an optimisation process that allowed a range of urban grid layout proposals to be tested in terms of airflow and thermal comfort. The process analysed the urban elements at three different levels: the microscale (compound layout), the mesoscale (street grid layout), and the urban canyon scale. Analysis was undertaken using the software ENVI-met, which is a computational fluid dynamics (CFD) model that can predict the urban microclimate for meteorological parameters (e.g. air temperature, wind speed, solar radiation and relative humidity) and estimate the impact of the prevailing microclimate on pedestrian thermal comfort. A validation study was performed on ENVI-met using Amman configurations to test the model’s sensitivity and accuracy in predicting the microclimatic change in the urban environment.

Yara’s results showed that local wind speed values changed greatly for different grid orientations. Pedestrian thermal comfort levels across the various grid layouts increased when the approaching wind angle was parallel to the streets and showed a significant decrease when the wind direction was at an angle of 45°to the street orientation. However, comfort levels were more sensitive to the different grid geometries rather than their orientations. The urban canyon scale analysis showed that increasing building height enhanced comfort and airflow, while a vegetation analysis of trees showed airflow was enhanced with lower Leaf Area Density (LAD) values, due to less aerodynamic resistance from the trees’ foliage.

Yara has presented her work at three major international conferences: 

Ayyad Y and Sharples S (2020) The effect of street grid form and orientation on urban wind flows and pedestrian thermal comfort. Proc. PLEA 2020, 35th International Conference on Passive and Low Energy Architecture, A Coruña, Spain, 1-3 September

Ayyad Y and Sharples S (2019) Envi-MET validation and sensitivity analysis using field measurements in a hot arid climate. Proc. SBE19 Conference, pp 1-9, Cardiff, 24-25 September 2019. IOP Conf. Ser.: Earth Environ. Sci. 329 012040

Ayyad Y and Sharples S (2017) Outdoor thermal comfort in a hot urban climate: analysing the impact of creating wind passageways in Al-Moski, Egypt using ENVI_MET. Proc. PLEA 2017, 33rd International Conference on Passive and Low Energy Architecture, Vol. 1, 997-1004, Edinburgh, 3-5 July 2017