EventGhost

I do something like that with my webpages. I have (with a lot of help...) programmed a script that takes in temp and humidity, checks it against the currently set "thermostate temp" and set humidity level (which I can also change from a webpage, but this page is in Girder). Then it checks if there is a change, and if there is the signal will be sendt to the heater in that room. If there hasn't been a change it checks if it's more than 5 minutes since the signal was sendt to that heater the last time and sends another signal if it is more than 5 minutes, in case something has happened in the meantime (like a quick power outage). It also starts and stops the fans in the bathroom and the washing room when the humidity reaches the set level. And the same script does the logging of temperatures, wind, humidity and barometer pressure. The webpage is password protected and can be used by any Javascript enabled browser from anywyere in the world. It also links to another page, which controls audio and video throughout the house, but that's a different thing.