Shared Heat Pump - Duplex House

I would like to ask a few more questions if that's okay? You are building 2 semi-detached houses each with 2 residential units, I assume that you want to live in one residential unit yourself and rent out one. That means you supply 2 residential units each with one heat pump, if I understood that correctly? I would be interested to know whether you record the consumption (heating and hot water) of the individual residential units in this constellation and whether you will carry out a flat-rate billing or consumption-based? And is there a "main apartment" that bears the joint costs and then allocates them proportionally to the "secondary apartment" in the form of additional costs?

Hi, there are no main apartment(s), I myself am moving into one residential unit, my brother rents out both residential units (but his son moved into one who “spontaneously” got stuck here from Hamburg shortly before completion due to Corona and lonely home office) We rent "warm" including everything (flat rate hot including 2500 kWh electricity and ??m³ water per residential unit, except Internet), nevertheless we record the consumption (electricity, water, heat) of each residential unit via lots of meters etc.

Good morning!

Thanks again for your feedback, I will try to summarize for myself what I have learned.

In this sense, doesn't the Legionella regulation also apply to such a construct? Meaning 60 degrees?

Honestly, the topic "Legionella regulation" was completely new to me and I had to quickly use a search engine :-)
Here's what I found quickly:

Corresponding systems in single-family and two-family houses are not considered large installations for drinking water heating under the Drinking Water Ordinance and are therefore not subject to routine testing obligations for legionella.

In the case of a semi-detached house, I am now unsure, since by definition it is not a "two-family house," but two independent single-family houses directly adjoining each other. The next question arises :-)

there is no main residence(s), I myself am moving into one residential unit, my brother rents out both residential units (but his son, who "spontaneously" wandered here from Hamburg shortly before completion due to Corona and lonely home office, moves into one)

Our cases are actually very similar :-) After 20 years of professional relocation, I am moving back to my hometown to be with family and friends.

I will now summarize the learned facts into two conceivable models, which may be taken up and evaluated to further elaborate the advantages and disadvantages:

Model A: Completely independent semi-detached house
- Real division of the property
- Separate financing
- Independent supply systems

Advantages:
- No complicated contractual constructs
- Unproblematic financing
- Unproblematic sale of one or both semi-detached houses
- Possibly advantages in dimensioning and thus efficiency of the heat pump

Disadvantages:
- Higher resource expenditure
- Higher initial costs
- Higher operating and maintenance costs


Model B: Declaration as a two-family house
- Financing by one party
- Construction handled by one party
- Subsequently rental/sale/lease purchase to the second party (possibilities to be examined)
- Property registration of easements for second party, similar to a condominium
- One supply system (heat pump, photovoltaic), operated by one party ("supplier")
- Consumption recording and billing via "warm rent" to second party ("recipient")
- If one party moves out, the remaining party would have to take over the role of "supplier" and the second semi-detached house would be rented out

Advantages:
- Lower resource expenditure
- Lower initial costs
- Lower operating and maintenance costs
- Simplified communication with architect, builder, etc. (only one contact person)

Disadvantages:
- More complicated contract
- Tax complications
- Dependence of both parties
- In the event of a forced sale, both residential units would have to be sold, as they are not independent
- Financing could be more problematic
- Increased effort for consumption recording
- Utility room must be accessible to both parties

I hope these insights help other members who are considering similar matters and I look forward to further feedback.

Many thanks and best regards!

But possibly tax advantages from renting due to the current option of special depreciation [Sonder AFA] for someone with a high tax burden?

In the case of a semi-detached house, I am now unsure, since by definition it is not a "two-family house," but two independent single-family houses directly adjacent to each other. The next question arises

I assume it is the question of the application of the guideline concerning plant operation. From this perspective, I would consider each half of the semi-detached house as a two-family house for the system and, with a shared system for the entire semi-detached house, practically as a four-family house.

... I suspect that each of you wants to live in one residential unit yourselves and rent out the other. That means you supply two residential units with one heat pump each, if I understood correctly? I would be interested to know whether you record the consumption (heating and hot water) of the individual residential units in this setup, and whether you will carry out a flat-rate billing or consumption-based billing? And is there a "main apartment" that covers the shared costs and then allocates them proportionally to the "secondary apartment" in the form of additional costs?

We have been running this principle for over 20 years, so far without problems: - each semi-detached house has its own circulation pump, heat quantity meter, and thermostat (weekly program) so everyone can run their own setback, frost protection, or daily program. (This of course assumes that the piping for each semi-detached house has exactly one circuit connection point.)

Only the supply temperature is controlled jointly (guided by the outdoor temperature).

The operating and maintenance costs are contractually charged according to the respective consumption.

Anyone who fears formal legal issues can possibly have an easement registered.