There are several options
- With Heating H2 you can manually override the calendar set temperature. The manual setting remains valid for a time set as an automation parameter; you could set that to 24 hours.
- You can set up the calendar for the ‘normal’ scenario (not there) and change them or write in additional events when he is present.
- You could up two automations for the same room - one for when he is there and one for when he isn’t, each with its own calendar. You can then switch between the automations by enabling and disabling them – which you could do from another automaton if you have an algorithm to do that.
- I don’t support it (yet) but someone took a fork of Heating X2 and modified it so that multiple temperatures can be specified in one calendar by prefixing each with a specific character. In your case you could specify different temperatures for when he is there and when he isn’t, and add an input switch “he’s here” to the blueprint to decide which of the two temperatures to adopt.