un met hours of internal comfort

[p1234567]

Hi,
I am designing a passive house and had entered all the envelope criteria along with profiles into IES VE.
after I do Apache Sim, I am facing some hours in April and October ( where I have no heating on) with low temperatures Dry resultant than the accepted comfort temperature. When I increase the HRV or Heating demand on for that period, it either gets over heated or temperature drops further.
I am trying to assess the reason to solve the problem. the system without any kind of ventilation (natural or auxiliary ventilation) and with heating in Jan, Feb, March, Nov, Dec. only had overheating period in April and October. I introduced natural ventilation in the profile with controls to reduce this overheating and provide good indoor conditions(CO2) so I got good conditions except for like 10 days in each month where I am getting below comfort temperature levels. I added HR V auxiliary ventilation for the provision of good indoor ventilation for such a compact house when the temperature is not overheating. either I get overheated or still this 10 day period is still below comfort level of temperature. Introducing heating is not helping either.

what do you think is the reason?
I know there should be some control profile philosophy to solve this issue.
please advice. is it normal that initially without natural or auxiliary ventilation while outside temperature is between -2- 15 C the indoor temperature in a passive house would be 30 C??? is it there any reason trigering this that I should take care of?
thanks in advance
R.K.