For the department Environment & Policy I created a QGIS plugin to perform building counts within noise contours.
The purpose of the plugin is to determine whether a building is located within a noise contour around an airport by using the cadastral data of buildings.
The plugin can only be used within the QGIS application.

QGIS is an open source Geographic Information System (GIS) with an easy toolkit to build your own plugins.

The data from the cadaster is available through various web services in different formats; WMS, WFS, WMTS, Linked Data.
But because the calculations are often covering big areas and the web services only handle a certain amount of objects per request, we decided to make use of a monthly PostGIS dump that we read into our own database.

The user can make a selection of the properties they want to include in the query by checking boxes and with a click of a button the calculations are made.
The end result is an Excel file including all the requested data and a data visualization.

The interesting thing about this tool is that both the GIS program and the data are completely open source. So this tool only cost development time.