Energy "concept" for old farmhouse

Very interesting project! Renewable energy for an old house. You will need a bit more energy per sqm than our tight new buildings - that's where efficiency considerations, which go in the direction of consumption costs, become particularly noticeable. My thoughts on this:

Photovoltaics always pay off with an unshaded roof and a southwest orientation in the Essen area. You can also consider capturing some east exposure, although it is not as productive per sqm on paper, but if you want to cover the base load of the house with your own electricity for a few hours longer, you might gain a few hours during which you don't have to buy expensive electricity. If you like, I would be happy to put you in touch with a friend for photovoltaics, who is currently doing a prominent photovoltaic project in Essen and can create a reliable yield calculation for you.

Heat pumps combined with underfloor heating are efficient heating systems - since you have a lot of space and probably not a rocky soil, I recommend you look into the ice storage heating system. It only makes sense with larger energy demands - which you have due to the large and old buildings. The principle is simple and maximally environmentally friendly: energy is stored in a concrete tank with water installed in the ground and extracted there by a heat pump through pipes with refrigerant. The trick is the use of the crystallization energy released when water freezes. The soil supplies the water tank with thermal energy through its constant temperature and "heats" the water back up against the energy extraction. Why? From my point of view, this system offers the advantages of constant geothermal heat without affecting the temperature conditions of the microorganisms in depth, which are important for good soil and water. At the same time, the heat pump can be set very effectively (constant conditions) and does not have the winter efficiency loss of systems that extract energy from the ambient air. Disadvantage: still relatively few installed systems on the market, "I don't know it - I don't build it" mentality of many installers and consultants.

The masonry stove heating has the immense charm for many people (us too) of a very pleasant radiant heat. Since you don't want to work with wood permanently, I would install this as a "luxury" secondary system. It takes some passion for wood processing to rely exclusively on such a system.

Our neighbors work with a wood log gasifier for heat. These now also exist with automatic feeding. No idea how reliable that is. That at least makes reloading simpler - the challenge of making (or having) wood remains of course.

Please keep in mind that these are only suggestions to think outside the box - I am, like many others here, not a professional. Most here have systems for new buildings, where calculations are done somewhat differently.

Heat pumps combined with underfloor heating are efficient heating systems - Since you have a lot of space and probably no rocky ground, I recommend you look into the ice storage heating system. It only pays off with a larger energy demand - which you have due to the large and old buildings.

Alternatively, also check out Ringgrabenkollektor (Ringgrabenkollektor). With some own work and through funding, an efficient and inexpensive heat source without an outdoor unit. In Essen, however, one can also be happy with an air-to-water heat pump, e.g. 2x 5kW Panasonic air-to-water heat pumps for 2,500€ per unit. The latter is particularly tested in old buildings and you can find many finished projects with descriptions from homeowners for both variants online. The most important thing with all heat pumps is the planning of the heating surfaces, hydraulics, and sizing. It’s not that complicated, but unfortunately you can’t blindly rely on craftsmen, KfW planners, etc. at this point. Don’t lose focus because of possible funding. First plan, then see how to integrate funding.

As far as I know, ice storage costs around 40K€. An absolute stillbirth. For that, you can do a lot of drilling, digging, or "inefficiently" extract heat from the air.

To my knowledge, ice storage costs around 40,000€. An absolute stillborn. You can drill a lot, dig or "inefficiently" extract heat from the air for that.

The high prices you mentioned occur when a solar thermal system is used for energy recovery in the water tank – but this is not mandatory.
By the way, the system can cool excellently in summer. The acquisition costs are higher, the operating costs low.

Not everyone just wants the lowest price. The OP will know what I’m talking about and can form their own opinion based on their criteria.

Renovation/modernization etc. of a half-timbered farmstead in a solitary location: a challenging undertaking that requires a holistic concept. First, it should be clarified whether this "solitary location" constitutes a planning law situation according to § 35 of the Building Code, namely the so-called "outer area," possibly associated with restrictions on use/change of use-

Half-timbering is a special shell construction, for the (energy) renovation of which different rules apply and different materials must be used than for a solid building, in order to build permanently without damage.

The question of the suitable heating system is inseparably linked with the decision about the extent and type of energy renovation (building insulation) and cannot be made independently. This also includes a room-by-room heating load calculation for system dimensioning, which takes into account the building insulation standard after renovation.

I urgently recommend that you discuss your planning considerations with an architect experienced in half-timbered constructions, who preferably also masters the field of building energy consulting for half-timbered buildings. The project should begin with a survey that examines the preservation status of the building and records possible building damages and the associated possible repair effort.

On this basis, a renovation concept can then be developed that integrates all involved trades and also takes the chronological sequence into account.

There is a planning systematics for this type of construction measures that should absolutely be followed in order to achieve a good result. This also includes as detailed and reliable cost calculations as possible.

Which heaters are unsuitable in timber-framed houses and why?