>> This energy analysis method addresses any buildings (residential, mixed and non-residential) of any urban areas in the world, insofar a virtual 3D city model and minimum building parameter inputs are available.
1. Start: Virtual 3D City Model
The start of the workflow is the virtual 3D city model, modelled in the open standard format CityGML.
One main advantage of the 3D city model format CityGML is its object modelling specification in different Levels of Details (LoD).
The simplest geometric representation of a building for a heating demand evaluation consists of a simple rectangular block. This block model is equivalent to the Level of Detail 1 (LoD1) of CityGML.
The Level of Detail 2 (LoD2) adds the roof form to the building level, Level of Detail 3 (LoD3) adds in the positioning of the façade windows, and Level of Detail 4 (LoD4) incorporates the modelling of the indoor space.
The SimStadt Simulation Environment handles all CityGML LoDs.
Such 3D City Models are generally created using LiDAR or stereo air photo, and enhanced with available semantic datasets such as building year, building usage, number of storey etc...
2. Healing of the Virtual 3D City Model
Given the diverse quality levels of incoming virtual 3D city models, the healing module CityDoctor offers a method of controlling and reparing the geometrical quality of the 3D City Model, for example, by closing polygons and volumes or separating buildings with common adjacent walls.
3. Geo-data management
Once the virtual 3D city model has been checked, it is then imported in the 3D Geo-data management system novaFACTORY, a keystone of the workflow.
Through specific Web-Based Services, this virtual 3D city model may be updated and refined, geometrically (with Google SketchUp) as semantically, for instance, by means of Crowd sourcing.
Systematic data pre-processing may further complete the semantic data of the virtual 3D city model, using benchmarking values from the building usage and building construction libraries to assess the missing building energy parameters needed for simulation.
Some energy scenarios, integrating global refurbishment strategies or/and new renewables energy supply, may be generated and saved in novaFACTORY, for use as simulation and comparison. Energy planners and decision makers of the city may use them to define the best urban energy strategy for the next decades.
All these data are stored in a 3D Geo-database, which may be exchanged with other stakeholders for different applications and analyses.
4. Energy Simulations
- heating/cooling demand calculation (monthly energy balance or hourly dynamical simulation)
- photovoltaic potential calculation
- simulation of renewable energy systems
- simulation of heating/cooling networks
Simulation results and performance indices such as heating demand, CO2 emissions, primary energy and energy saving potentials may be visualized in the virtual 3D city model and analyzed in a decision making module.