Over the last decade, outdoor thermal comfort has become of considerable significance to urban de-signers and planners. In that concern, parametric design models were acknowledged for supporting the design process with iterative performance-based solutions and for being relatively less time and resource consuming. However, validation studies for such parametric models on the outdoor urban scale are lacking. Meanwhile, stud-ies concerned with geometry optimisation are computationally expensive due to the time required per each simu-lation. This paper consequently investigates the accuracy and time efficiency of using the workflow comprising the environmental analysis Ladybug-tools, the plugins of Grasshopper3D for modelling the outdoor microclimate. The study verifies the modelβs results against the microclimate CFD simulation tool, ENVI-met. The two models are compared in terms of two environmental metrics, the mean radiant temperature and the universal thermal climate index. In this paper, three hypothetical layouts representing basic urban geometry patterns, namely linear, dotted, and courtyard, are simulated in both models. Results show an acceptable range of consistency between Ladybug-tools and ENVI-met, particularly during the hours 8 am to 5 pm. Timewise, Ladybug-tools show their capabilities of not only modelling the microclimate but also their suitability for optimisation studies characterised by a vast number of design solutions
