About City Digital Twin Project
City Digital Twin Pilot Project aims to implement the digital twin as a technical solution that scales to real-world problems, including design, exploration and experimentation of urban environment and processes.
3D City Model
The 3D city model of District Lozenets and its visualisation are the first steps towards implementation of City Digital Twin pilot project of GATE Institute. It covers the Buildings and Relief thematic modules of CityGML 2.0. The 3D model of the buildings is hosted on the Cesium ion platform and visualized using CesiumJS.
Key words: 3D City Model, CityGML 2.0, Cesium ion, CesiumJS
Generative AI Empowered 3D City Model
The study develops a cutting-edge Urban Digital Twin based on LLAMA 3.1 (70B), fine-tuned using the QLoRA method, and integrates air pollution data from Sensor.Community. The proposed system processes over 1 billion records of historical and current air quality data in the Sofia region, creating an interactive 3D city model.
Key words: Generative AI, 3D City Model, Air Quality
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Pedestrian wind comfort
Computational Fluid Dynamics (CFD) simulations are now being widely used for the prediction and assessment of high-rise building aerodynamics and pedestrian wind comfort. Results from CFD wind simulation are reliable sources of quantitative and qualitative data useful to make important design decisions.
Key words: CFD, building aerodynamics, wind flow
Indoor air quality & thermal comfort
Indoor air quality and thermal comfort are two factors that affect occupant’s health, performance, and overall well-being. They are modelled, analyzed and predicted by applying CFD, so that suitable control measures can be taken in due time. The overall building design, ventilation and heating effectiveness is assessed and optimized through different what-if scenarios.
Key words: CFD, air quality, thermal comfort
Project
Child Facilities Coverage
An automated approach for assessment of social facility coverage is developed. It solves a supply and demand problem based on a graph network, where kindergartens and nurseries are considered as supply nodes, and residential buildings as demand nodes. Supply and demand are balanced based on a 15-min walking distance and the capacity of social facilities.
Key words: Network analysis, walkability, public facilities coverage
Publication
Geospatial Air Quality Prediction
The aim is to provide a way of combining data from different sensor stations and to develop a platform for the real-time prediction of air quality throughout Sofia city. To achieve this, methods from the field of uncertainty quantification and statistical learning are used, which enable the analysis of existing sensor data in a probabilistic way.
Key words: Air quality, geospatial prediction, uncertainty quantification
Project
10-Minute Walkable City
Walking is the most accessible form of mobility, delivering benefits to both cities and their residents. To increase walkability, the pedestrian network, integrating all transportation modes, should be optimized. The pedestrian accessibility to public transport stops and parks in Sofia is evaluated by applying network and spatial analysis based on a 10-min walking distance.
Key words: Walkability, Urban Network Analysis, Spatial Syntax
Publication
Urban Heat Islands
The study aims to numerically estimate the impact of UHI in Sofia and its surroundings on the air temperature using the state-of-the-art Weather Research and Forecasting (WRF) with very high resolution. The study also estimates the impact of building and transport separately ...
Key words: Urban Heat Island, Thermal environment, Energy consumption, WRF model, Numerical simulation
Project
Buildings Energy Consumption
The study calculates the energy consumption of the residential buildings in Sofia based on the “Building certificates of energy characteristics” dataset, provided by the Agency for Sustainable Energy Development. For each building category, a distribution-free tolerance interval is computed ...
Key words: Energy Consumption, 3D City Model
Project Publication
Walkable Cities
This study applies the 15-minute city concept and introduces an Accessibility Index that evaluates residential access to POIs, incorporating diversity metrics such as the Shannon and Simpson indices.
Key words: Walkability, Accessibility, Urban Facilities, Residential Buildings
Project
Large-Scale Solar Potential Analysis
This study examines the calculation of solar incident radiation at the city scale in Sofia using remote sensing data for the large shading context in a mountainous region and 3D vector building data. The building footprints and the terrain are preprocessed using GIS. The solar calculation is con-ducted using a raytracing algorithm in 3D CAD at the city scale.
Key words: Solar radiation, CAD tool application, 3D city model
Publication
Traffic Monitoring and Simulation
The study focuses on developing a novel digital-twin-based approach for micro-traffic simulation to support data-driven decision-making for increasing traffic safety through scenario planning. Leveraging the traffic data obtained through monitoring one of the busiest intersections in Sofia city, this research workflow shows the effective integration of LiDAR data and the urban digital twin concept in intelligent transportation systems (ITS).
Key words: Traffic Data Enrichment, Traffic Monitoring, Transportation Planning
Publication
Urban Heat Risk
The study explores the heat index Wet Bulb Globe Temperature (WBGT) in the center and suburbs of Sofia. The results show that the incorporation of street trees provides shading, which substantially mitigates thermal discomfort by reducing direct solar radiation exposure and lowering surface temperatures.
Key words: Heat Risk, Wet Bulb Globe Temperature, Pedestrian Comfort
Project
Urban Digital Twins for Green Mitigation
The study aim to enhance Urban Digital Twins as dynamic decision-support tools for mitigating environmental impacts and promoting sustainable, green urban development. It proposes an advanced framework that integrates high-resolution climate simulations by the Weather Research and Forecasting model to evaluate and compare urban development scenarios.
Key words: Green Mitigation, WRF Simulation, Urban Heat Island
Project
Causal Impact of Metro Network Expansion
The study explores surrounding of the metro stations Within the 0.8 km buffer zones, where there has been an increase in building density and total gross floor area (GFA). This transformation has led to a significant rise in energy consumption, particularly in densely built-up areas.
Key words: Metro Expansion, Urban Growth, Energy Consumption
Project
Generative urban design
The parametric urban planning naturally follows the basic idea of the digital twin – "design, test and build first digitally". A tool that provides data-driven decision support on urban planning is developed based on preliminary defined neighbourhood indicators related to population density, access to social infrastructure, transport connectivity, etc.
Key words: parametric urban planning, genetic algorithms
Project
Location-Allocation of Social Amenities
The social amenities allocation is a challenge in urban planning, requiring an optimal distribution of their locations to accommodate demand while ensuring accessibility. The proposed novel approach tackles it using Constraint Programming, utilising MiniZinc language to formulate the problem, and the Gecode and Chuffed solvers to identify feasible allocations.
Key words: Location-Allocation of Social Amenities, Spatial Optimization, Urban Planning
Project
3D City Model of Lozenets
The 3D city model of District Lozenets and its visualisation are the first steps towards implementation of City Digital Twin pilot project of GATE Institute. It covers the Buildings and Relief thematic modules of CityGML 2.0. The 3D model of the buildings is hosted on the Cesium ion platform and visualized using CesiumJS
Key words: 3D City Model, CityGML 2.0, Cesium ion, CesiumJS
Generative urban design
The parametric urban planning naturally follows the basic idea of the digital twin – "design, test and build first digitally". A tool that provides data-driven decision support on urban planning is developed based on preliminary defined neighbourhood indicators related to population density, access to social infrastructure, transport connectivity, etc.
Key words: parametric urban planning, genetic algorithms
Project
Child Facilities Coverage
An automated approach for assessment of social facility coverage is developed. It solves a supply and demand problem based on a graph network, where kindergartens and nurseries are considered as supply nodes, and residential buildings as demand nodes. Supply and demand are balanced based on a 15-min walking distance and the capacity of social facilities.
Key words: Network analysis, walkability access, public facilities coverage
Project
Pedestrian wind comfort
Computational Fluid Dynamics (CFD) simulations are now being widely used for the prediction and assessment of high-rise building aerodynamics and pedestrian wind comfort. Results from CFD wind simulation are reliable sources of quantitative and qualitative data useful to make important design decisions.
Key words: CFD, building aerodynamics, wind flow
Project YouTube
Geospatial Air Quality Prediction
The aim is to provide a way of combining data from different sensor stations and to develop a platform for the real-time prediction of air quality throughout Sofia city. To achieve this, methods from the field of uncertainty quantification and statistical learning are used, which enable the analysis of existing sensor data in a probabilistic way.
Key words: Air quality, geospatial prediction, uncertainty quantification
Project
Indoor air quality & thermal comfort
Indoor air quality and thermal comfort are two factors that affect occupant’s health, performance, and overall well-being. They are modelled, analyzed and predicted by applying CFD, so that suitable control measures can be taken in due time. The overall building design, ventilation and heating effectiveness is assessed and optimized through different what-if scenarios.
Key words: CFD, air quality, thermal comfort
Project
Urban Heat Islands
The study aims to numerically estimate the impact of UHI in Sofia and its surroundings on the air temperature using the state-of-the-art Weather Research and Forecasting (WRF) with very high resolution. The study also estimates the impact of building and transport separately..
Key words: Urban Heat Island, Thermal environment, Energy consumption, WRF model, Numerical simulation
Project
10 Minutes Walkable City
Walking is the most accessible form of mobility, delivering benefits to both cities and their residents. To increase walkability, the pedestrian network, integrating all transportation modes, should be optimized. The pedestrian accessibility to public transport stops and parks in Sofia is evaluated by applying network and spatial analysis based on a 10-min walking distance.
