Natural gas consumption, gas condensing boiler, OK? Where is the greatest potential for optimization?

Hello everyone,
I would like to know your professional opinion on where there is still potential to optimize our natural gas consumption. It feels like and is also measured against the calculated energy demand that we consume too much.

Initial situation:

approx. 185 sqm living space
2 full floors, no basement,
flat roof, 20 cm insulation between rafters WLG 035 plus on average 9 cm insulation above rafters with slope
with attached double garage (not heated) and heated technical room extension within the thermal envelope, otherwise no bay windows, projections, or similar
Masonry: 20 cm sand-lime brick + 16 cm ETICS WLG 032
Gas condensing boiler Brötje WGB Evo 20 G with Q = 2.9 - 20.0 kW
approx. 16 sqm solar thermal (in operation since 24.04.19) with heating support
Buffer storage with 1,000 liters volume
Central controlled residential ventilation with heat recovery (in operation only since 04.10.19, thus negligible)
Comfort setpoint 25°C, reduced setpoint 18°C, heating curve at 0.64, hot water at 60°C
Night setback between 10:00 p.m. and 5:00 a.m.

Temperatures at 22°C in the living area, 22.5°C in bathroom 1, 21°C in bathroom 2, hallway 21°C, bedroom heating basically off, children’s room and office approx. 20°C.

2 adults who shower daily in a normal frame and 1 toddler (3.5 years old), bathing max. once a week

Consumption from Nov. 2018 to Nov. 2019 around 1,250 cubic meters of gas, roughly 12,500 kWh. This now includes cooking with gas, here I estimate no more than 100 cubic meters. In my opinion, this is already quite a lot.
Calculated consumption without controlled residential ventilation would be around 10,000 kWh, so the consumption is about 1,500 kWh too high.

In your opinion, where is the greatest optimization potential?
What do you think of Brötje?

Best regards
Ippebson

Nowhere, the consumption is ok.

It's fine. The controlled residential ventilation could still work.

Where do you think the greatest optimization potential lies?

Flow temperature as low as possible, see the neighboring thread with the children's room. No night setback (requires higher flow temperature). The heating should cycle as little as possible. This way you make better use of the condensing effect and I could also imagine – without knowing the control behind it – that the solar thermal heating support becomes more efficient.

However, the effect will not be huge.

Thanks first of all for the feedback! I will save that everything is okay so far. I would try turning off the night setback. However, in the neighboring thread (the one with the children's room) it is also mentioned that the heating curve often lies below my set heating curve, at 0.4 or 0.25. Is this actually dependent on the type of heating?

I currently have a flow temperature of around 40 degrees C, as far as this corresponds to the displayed "boiler temperature." But it should be like that, right?

Best regards