Outdoor Comfort in the Cold; CFD-Informed Microclimate Design for Subarctic Cities

Abstract

This thesis investigates how urban morphologies and spatial configurations can be adapted to Arctic conditions, with a focus on environmental comfort and resilience. The thesis aims to evaluate how variations in urban morphology influence outdoor thermal comfort in Kiruna’s subarctic climate. Using Kiruna as a case study, a city relocating due to mining induced ground deformation, the research addresses the need for climate responsive urban strategies in an extreme environment. Due to ongoing climate change, Kiruna is experiencing rising average temperatures, increased rainfall, greater seasonal variability and extreme weather. This creating new challenges for outdoor environmental comfort and climate resilient planning. This in turn highlights the need for iterative design workflows that directly integrate CFD analysis and microclimate data. A persistent knowledge gap exists between architects, planners and engineers regarding the use of CFD simulations, microclimate knowledge and simplified climate studie methods. Although increasingly recognized as essential for resilient development, these tools remain poorly integrated in mainstream practice due to differences in technical training, methods and professional boundaries. This highlights the need to translate complex environmental analysis into accessible and design driven insights for subarctic development. The study includes interviews, microclimate modelling, wind and solar radiation simulations and comparative case studies to evaluate the performance of several urban configurations. Simulations are carried out using Autodesk Forma and Forma plugins for Rhino 8 which assesses solar exposure, wind flow and microclimatic interactions. The workflow is iterative and scenario based, using seasonal boundary conditions to compare typologies and street configurations against outdoor thermal comfort criteria. The results are based on comparisons between different examples of urban morphology. These have been tested within the subarctic climate and urban context of Kiruna. The design is grounded in the insights and outcomes generated by the tests. One configuration will then be developed in detail, integrating rainwater management, social functions and green infrastructure. Ultimately, the thesis contributes a design oriented framework that bridges environmental simulation and urban morphology, supporting resilient and comfortable public realm design in subarctic contexts.