## 5 Retrofit Design Estimations vs. Dynamic Energy Simulations
### Building Energy Modeling and Simulation Methodology  
The overall holistic building energy modelling and simulation methodology that were developed by [PERSON] et al. [46] were employed to model and simulate the schools' energy performance. Three tools  
Figure 7: Average monthly ambient air temperature in Odense—pre-retrofit vs. post-retrofit data. were used, Sketchup Pro for developing the detailed 3D architectural model of the school, OpenStudio to develop the energy model and define various building specifications and characteristics, and finally the EnergyPlus engine for running an annual energy performance simulation for the three schools. A comprehensive and detailed energy model is needed in order to carry out a holistic and accurate simulation of building energy performance. Such a model shall take into account various building specifications along with boundary conditions, operational dynamics, and ambient environment. Thus, inputs to a proper and detailed dynamic energy model include, but are not limited to, location and orientation, building envelope properties, construction materials, HVAC systems, climatic conditions, building services, equipment and lights, room types and schedules, occupancy behavior, and patterns. In this study, the EnergyPlus simulation engine is used to carry out a detailed dynamic annual building energy performance prediction. EnergyPlus is very well validated in the field of building energy modelling with various capabilities in terms of building operation simulation and performance prediction. In addition, two supporting tools are employed in order to allow for a smooth transition from building 3D architectural model to a full-scale building energy model. Google Sketchup Pro is first employed to create the 3D model of the considered schools with an accurate depiction of the different blocks geometry and orientation including the detailed rooms, spaces and thermal zones allocation. The 3D model is then introduced to OpenStudio, which allows for a more user-friendly interface for building energy model development compared to the default EnergyPlus tool. In OpenStudio, all of the building characteristics and various specifications mentioned above are defined and highlighted including different building design and operational parameters. Figure 8 provides an overall picture of the modelling and simulation process that are adopted in this work. The overall modeling and simulation methodology employed for the three schools starts with the (1) Building Information and data collection phase, where all school building blocks information and design and operational parameters are collected, along with geometry drawings, datasheets, systems information, and construction sets. Subsequently, in the (2) Architectural 3D model design phase, a full 3D model of the building is drawn in Sketchup Pro with all blocks' details and geometry. This 3D model is then introduced to OpenStudio in (3) Holistic energy model development, in order to define all specifications and develop the holistic schools' energy models. When the schools' models are ready, a complete energy performance simulation is carried out in (4) Building energy performance simulation. This is followed by a (5) Energy model calibration phase, where energy data that were collected from meters in the schools are used to calibrate the developed dynamic energy model. As the calibrated dynamic model of the school is ready, phase (6) Energy renovation measures and packages implementation is performed, where a large number of retrofit measures and packages listed above in each school is implemented in the energy model in order to simulate the impact of retrofitting the various building blocks. Finally, the simulation results are obtained in the final phase  
Figure 8: Overall building energy modelling, simulation and retrofit assessment methodology.