Yes, that’s one version of the balance point temperature, but keep in mind it’s just a guide as its still a summarization of a timeseries, so it’s not surprising it won’t give you zero heating/cooling for all of July.
I think it’s a lot clearer to simply plot the temperatures against the setpoints, and see where your zone air is activating heating. I’ve plotted temperatures for just July below to illustrate the problem. Green = Exterior air temperature, Purple = Zone air temperature, Light Green = Cooling setpoint at 24.4C, Red = Heating Setpoint at 21.7C. The separate graph below the temperatures shows the heating load (red line).
July - No Ventilation
Without ventilation (just ideal loads), you can see there’s definitly some influence of midday internal heat gain that is keeping the zone air higher then the exterior air temperature, but despite that your heating load in July is much larger then your cooling load. Which means that there’s not a lot of hot temperatures to cool down in the first place.
I didn’t look at your energy balance closely enough and missed this, but the main problem is really just the heating (system) dominated summer.
July - Ventilation Minimum Outdoor Temp = 12C
The too-low minimum ventilation setpoints are, unsuprisingly, just compounding the heating in July.
Here’s the ventiltaion with a 12C minimum ventilation temperature. The zone air is at the heating setpoint the vast majority of time. At colder exterior temperatures, the zone air actually goes lower then the zone heating setpoint. Caveat: this is with very minimal parameter tuning (shutting down some windows, reducing operation area, adding a room minimum temperature setpoint), but there’s so few cooling days I don’t think it matters.
Yes, that’s the first thing you need to fix then. It sounds like you may need to massively increase your internal heat gains, and insulation to reflect the building condition you are looking for, maybe even find a more representative EPW. One parameter that seems particularly unrealistic to me is the default heating setpoint of 21.7. That’s high for european residential occupants using natural ventilation, since I think they should tolerate a broader range of temperatures.
But I don’t think there’s anything unusual in the heating and natural ventilation loads as it is currently, that’s just the logical outcome of your current EPW and BEM combination.