IFC-based analysis of present and future thermal comfort using building energy performance simulation and computational fluid dynamics

Mitigating the impacts of climate change on ecosystems and humans requires reducing greenhouse gas emissions. To achieve this reduction, political organizations such as the European Union (EU) have established targets for emission reductions, which are ratified nationally. In recent years, Germany has failed to meet its targets, partly due to the energy consumption of buildings driven by their heating and cooling demands. Suitable simulations allow for capturing the dynamic thermal performance of buildings, which can be used not only to evaluate energy efficiency but also to predict indoor thermal comfort as a driving factor in the operation of Heating, Ventilation, and Air Conditioning (HVAC) systems. However, previous research has criticized the model setup for Building Energy Performance Simulations (BEPS) and Computational Fluid Dynamic (CFD) simulations for requiring high manual effort, limiting their use in the decision-making process on energy-efficient building design. These simulations also lack interoperability within collaborative processes with the Building Information Modeling (BIM) approach. Therefore, this dissertation presents approaches for the automated setup of BEPS and CFD models within a BIM-based design process of buildings using the open data exchange format IFC as a representation of BIM data. The proposed methods address current challenges in the automated transformation of IFC data into simulation model input. The IFC-based BEPS setup uses template-based enrichment for building constructions and zone usage to compute the thermal performance of the building at hourly resolution over a full year, including air and surface temperatures, heat fluxes, heating and cooling loads, and energy consumption. The BEPS results of a selected timestep are used to define the boundary conditions for the IFC-based CFD simulation. This CFD simulation is then used to calculate the indoor air distribution, which can be further used to optimize the operation of the HVAC systems. These IFC-based simulations form the basis for an IFC-based thermal comfort setup, which uses an extension of the template-based zone-usage enrichment for personal comfort parameters. This combined approach allows for efficiently evaluating static, local, and adaptive thermal comfort. Based on the evaluation of the annual hourly BEPS results, spaces with a high risk for thermal discomfort are evaluated in detail on their local thermal comfort through CFD. This combination enhances the reduction of computational cost by selecting only critical cases for an in-depth CFD analysis, while the overall building thermal performance is evaluated using BEPS. The proposed approaches are applied to evaluate the impact of climate change on the energy efficiency and thermal comfort of indoor environments on different spatio-temporal scales. In addition, future energy demand and thermal comfort are predicted, and the performance of available heating and cooling capacities is evaluated under future weather conditions. Within this dissertation, the evaluation of the results for a non-residential building under future weather conditions resulting from the IPCC scenario SSP5-8.5 for the year 2050 indicate a doubling of the cooling capacity requirements, leading to an increase of cooling energy consumption of 400% and a reduction of the heating energy consumption of 30%. The presented approach on automated IFC-based simulations allows for assessing the dynamic effects in a building's thermal performance while considering both the current and the future climatic conditions. This consideration then enables evaluating the performance over the building's life cycle, supporting a paradigm shift in decision-making in the building design. By predicting future heating and cooling loads, a significant step towards an optimized, energy-efficient, comfortable building design will be achieved, providing high thermal resilience to the impact of climate change.