Which heating is recommended for KfW 55?

You are mixing the energy saving ordinance standard with the heating technology costs.

Building envelope and heating technology belong together for me. They have to fit.

Here the kfw55 standard is specified by "amazingbee".

He is trying to achieve that with a gas heating system.

Therefore my suggestion is to reconsider the KFW-55 standard and possibly choose another one.

Tomorrow I will calculate the costs of our gas condensing boiler in the new building with connection and so on. The last gas condensing boiler in 2008 (old building) cost €3,800 including installation, without hot water.

Another "can't be" comment - I already got one like that recently from a lady here in the forum. Do I seem that unbelievable?

Let's take the Viessmann Vitocal 343-G, so as not to use a cheap device as a reference. COP 4.6.
Price including 200l hot water storage: €8500 (gross)
Plus a surface or trench collector.
Material cost around €900 for pipes plus antifreeze and distributor... let's generously say €1700.
That makes €10200 plus excavation plus beer and sausages for the collector helpers.
Makes €11000? €11500?
Minus €4000 subsidy, that makes €7000-7500. With a cheaper heat pump correspondingly less.
I think a gas boiler + storage + flue + gas connection costs at least the same, even though I haven't had one quoted - tell me where you think the price would be! Installing, connecting, etc. will be about the same cost.

If drilling is absolutely necessary or wanted, of course the situation looks different - that would have immediately pushed my total costs up by a hefty €10000...

The gas system is included as standard in the offer from the building contractors (all the contractors I dealt with).

Additional costs are about €5000 (gas connection, tank provision, earthworks). Rental of the tank etc. I can say when I find my note again, where I wrote down the offer.

Oh yes, a gas boiler itself costs around €4000 depending on the manufacturer.

Now a question from my side as well, because we are also really interested in this.

We are also in the process of building to KFW70 standard (which is required). Air-to-water heat pump from Wolf (BWL 1A). Now the consideration is to go straight to KFW55, as we thought that with 36.5cm Poroton T9, triple-glazed windows and insulated basement, floor ceiling and slab, the effort would not be particularly high anymore.

Why the consideration? Because we want to reduce the monthly electricity / heating costs of the heat pump or the consumers in the house in general.

From my point of view, there are the following possibilities

1) Combine KFW 55 building envelope with air-to-water heat pump, which should reduce consumption, save money on the heat pump and on primary energy demand
2) Combine KFW 70 building envelope with brine heat pump with trench collector / drilling. More expensive, but less electricity costs for the heat pump
3) KFW 70 with air heat pump + photovoltaics on the roof including storage. Probably the most expensive solution or similarly expensive as option 2, but with own yield and the possibility to operate other consumers with self-generated electricity and thus reduce electricity costs.

In summary, we want to reduce monthly electricity costs with the most efficient option possible.

At the moment, I tend towards option 1. However, we do not want controlled residential ventilation... do we even have a chance then?

Who can clarify these questions for us? The builder or can only the energy consultant do that with certainty? We would like to have that clarified before signing.

What would you do?

The energy consultant should be more objective; whether it helps if the BU has no idea how to install their proposed variant is still questionable. In my opinion, you are more independent from electricity price developments in the long term with a ground source heat pump than with an air source heat pump because the ground source heat pump generally requires less electricity to produce the same amount of heat.

@Lexmaul: When exactly did you apply for the Bafa subsidy? As far as I understand, you have to do that before commissioning anything (drilling?). Unfortunately, our general contractor has no knowledge of geothermal energy. We also chose a brine heat pump with earth drilling for KFW 55.

You may have already done the drilling - the important thing is that you have not yet signed a contract regarding the heating. An offer for the heating must also be enclosed with the application. My application was only sent out last week because I was waiting for the new heating system from Vaillant.