Air heat pump or use gas and solar?

It is enough for me to know what the additional costs are for a non-Kfw 70 house of the same size.

We are currently searching for construction companies. One offers heat pumps cheaply, the other swears by gas. If I build with the one who likes to sell gas, he will definitely not be able to offer me the heat pump as cheaply after the heat demand calculation as the other who sells these parts in large quantities. How am I supposed to determine the heat demand beforehand? Everyone will probably tell me something different, if anything at all.
It is supposed to be a KFW 70 house (as already said).

I can already see that only a few people here can really help me... apparently there is still too little experience on this topic.

What helps me are statements like those from Cascanda. At least I can make some use of those.

..How am I supposed to determine the heat demand beforehand? ..

Even a layperson is overwhelmed by this. To prevent everyone from telling different things, this should be done by a sales-independent MEP planner

best regards

Hello,

How am I supposed to determine the heat demand beforehand?

You better not do that. Maybe you should get a professional planner who can assist you a bit with it..........

Regards

How can you want to build a house without knowing beforehand what operating costs you will have later for heating, hot water, and possibly ventilation?

Quite simple. If you have paid so much before that it can only be less in the new house, regardless of the type of heating. That's how it was for me. We previously (semi-detached house, 120 sqm) paid 475,- per month for electricity and gas. It can't get more expensive...

Hello Euro!

How can anyone want to build a house without first knowing what consumption costs they will later have to expect for heating, hot water, and possibly ventilation. I would never think of that.

Nice to see that I’m not the only one "professionally ill" when it comes to "my" topics

What good does it do me to know the consumption beforehand?
Except, of course, for the correct sizing of the heating system.
And with a gas condensing boiler, you apparently can’t go too wrong in the design, right?

Whether I have 50 euros or 500 euros per month, I have to live with it (as I said: if I have done everything necessary to optimize the heating system). I still won’t give up building a house because of that...

I can’t draw conclusions about my house from a small rental apartment. It already starts with not knowing whether I will run the controlled residential ventilation in summer or not -> that alone causes a 50% variance in the electricity consumption of the controlled residential ventilation...
When I finally have a proper bathroom with a proper bathtub – how often will I (and especially my wife) bathe in winter? Probably more often than now – but how often??
Will we really light the stove as often as I’m imagining now? And if yes – how much will it heat the upper floors? Or will I be completely dependent on the gas boiler there?

These are all little questions I have no answers to beforehand – but which can significantly affect my consumption costs overall...

Best regards!

Micha

...What use is it to know the consumption beforehand?

How else can an economical system be found, an investment be evaluated?

...Whether I have 50 euros a month or 500. I have to live with it (as said: if I have done everything necessary to optimize the heating system). I will not give up building the house because of that...

I would rather prefer the option with 50 euros Also, one does not have to live later with some undefined consumption, but can influence it in the planning phase. Low consumption means investment. But how much, what is economical and practical?

...I cannot infer my house from a small rental apartment.

Correct, that is why an exact determination of demand is made for the concrete object taking into account the specific boundary conditions.

...When I finally have a decent bathroom with a decent bathtub – how often will I (and especially my wife) bathe in winter? Probably more often than now – but how often??

Higher demand always leads to higher consumption. 25°C indoor temperature requires higher energy use than 20°C indoor temperature. That is not without reason, for example, when calculating the heating load, the desired room temperatures are agreed upon.

...These are all small questions to which I have no answer beforehand – ..

But they can be answered beforehand by defining a general comfort scenario for oneself. Anything that deviates from this later means a change in consumption. Even a worst-case situation can easily be represented. Anything more automatically means increased consumption. Comfort and luxury cost money. With efficient technology, this "more" is always less pronounced.

Best regards

NB: Comparisons may be flawed, but still: Who buys a car without knowing the consumption data beforehand? Someone who drives little might be able to settle for a cheap gas guzzler, but someone who has to drive a lot will have to pay attention to low consumption values and therefore rather prefer a somewhat higher-priced vehicle.
Energy prices for all energy carriers will rise significantly. One can relatively quickly get rid of an uneconomical car; with a building, it is considerably more difficult.