In the context of climate change, the increasing demand for energy-efficient buildings and sustainable urban development has become a pressing issue due to the significant proportion of global energy consumption and carbon dioxide (CO2) emissions attributable to the building sector. This requires a concerted effort to reduce its environmental impact, and Geographic Information System (GIS) applications are vital tools for achieving this by optimizing heat supply, calculating costs, analyzing profitability, and balancing CO2 emissions. This study aims to address the challenge of achieving energy efficiency and reducing CO2 emissions in the building sector, specifically at the district level. To this end, the research objective is to develop a QGIS plugin that can simulate urban energy demand at the district level by integrating 2D data with CityGML files and connecting QGIS to SimStadt software via API to visualize the simulated urban energy results in 3D on the Web Globe. The proposed plugin leverages the open-source QGIS tool QField to capture building conditions and connect 2D and 3D data on urban energy simulation. Supplementary to this, this plugin provides up-to-date information on energy demand, consumption, CO2 emissions, building component conditions via updating related tables in the database. Decision-makers can use this comprehensive and user-friendly tool to understand and act on the results, ultimately leading to a CO2-neutral district by 2045. The development of the QGIS plugin represents a significant step towards sustainable urban development and climate change mitigation by utilizing GIS applications for optimizing energy demand and reducing CO2 emissions in the built environment.

Keywords: Energy demand estimation, reducing carbon dioxide, ALKIS and CityGML data, QGIS plugin, 3D visualization

In recent years, neighborhood energy-efficiency concepts and implementation management have become more important in improving urban redevelopment projects in terms of cost-effectiveness and protecting environment and human health. Recently, considering the energy consumption and energy simulation are the mandatory and preliminary factors before starting an urban planning project. One of the main target of this paper is how to calculate the energy consumption in the easiest way with the appropriate accuracy in a short period of time without huge programming background and with license free software that are known for surveyors, architectures, city planners and geographers. Our work represents how the usage of the open source GIS software can be implemented for energy demand calculation and as result for a map visualization. At first, the necessary data, geometry and relational tables, which are mostly related to building information such as number of floors, windows, building age and etc., must be defined as a schema in PostgreSQL database. Secondly, for data acquisition, QField software which is the open source plugin in quantum geographic information (QGIS) system will be used. In the last phase of the project, those captured data will be synchronized from QField in QGIS software and spontaneously in PostgreSQL database. In addition, some important information from LOD2 (level of detail) data with XML format which contains standardized of roof type and height of building can be added for accuracy determination of result.

Keywords: Cadastre; Geoinformation/GI; Spatial planning; Urban renewal; Young surveyor; Open Source GIS; PostgreSQL Database; Energy Estimation; Urban Planning