Flags for Good has a lot of great flags available, if you want to peruse their collection. https://flagsforgood.com/

District heating systems have fascinated me since I learned about them and I wish I could find more information on things like the financial costs and work involved in converting existing neighborhoods to block heating, etc. I don’t like having single points of failure, but the idea of having some kind of central heating station for every square mile or something seems like a happy medium and I’m curious how the numbers actually play out.