I had 64 kWh in June.

I calculated with 85kWh. I would pay CHF 7.65 for 85kWh.
I leave the air conditioning running during the day (target temperature 20 degrees) and switch it off at night. The room then stays pleasantly cool until the next morning.

That depends on how long you need the appliance. Whether you heat with it in winter. How hot it is outside.
In summer, the appliance needs an average of 0.2 to 0.5 kw/h
So per hour.
That's a super good value. My predecessor needed 1.6 kWh.
In winter, 1kw/h generates a total of 4 kw of heat.
So you need 8 hours of operation per day in summer,
8x 0.3 kWh, i.e. 2.4 kw/h.
Approximately 75 cent.