A novel comprehensive workflow for modelling outdoor thermal comfort and energy demand in urban canyons: Results and critical issues

In the energy simulation of buildings there has been little focus on their impact on the microclimate; simulation tools have usually dealt either with building or with outdoor simulation, and only recently these aspects are being interconnected. Within this framework, the paper describes a novel simulation workflow developed in the Grasshopper environment, where the Ladybug Tools are used to model the mutual relations amongst urban microclimate, building energy performance and outdoor thermal com- fort. With reference to an urban canyon located in Catania, Southern Italy, the workflow –by coupling the indoor and the outdoor thermal field –provides both the dynamic thermal load of the buildings overlooking the canyon and the parameters needed to measure the outdoor comfort perceived by pedes- trians. In comparison to other existing approaches, this workflow offers significant flexibility and makes it possible to perform a parametric investigation of the effects of different design solutions on both the indoor and the outdoor environment. The outdoor Mean Radiant Temperature calculated through the model is compared to on-site measure- ments performed with a black globe thermometer during two different days in the summer. The compar- ison suggests good agreement in the shaded areas of the canyon, but a non-negligible overestimation in sunlit areas. These results have driven the authors to a critical insight into the algorithms implanted in the Ladybug Tools, and have helped to highlight some critical issues that will be further investigated in upcoming research.