Hi Laura,
So is the idea to create some sort of statistics on heating by Gemeinde?
If so, I think you are better of downloading our Gemeindegrenzen from our open data website (
here)
and then also download heating type data
hereand process that in QGIS or other tools to help you sort out features you want to count.
Our API doesn't really make it easy to filter feature from the ch.bfs.gebaeude_wohnungs_register_waermequelle_heizung layer with a specific geometry. It will work based on map extent, but then you'll have to filter results again and check that they are withing a specific Gemeindegrenze. (tons of requests, maybe easier to achieve that directly in QGIS with raw data)
Is that what you wanted to achieve?
Cheers,
Pascal