ᐅ Heating System for a Bungalow with Two Residential Units

Hello dear forum community,

My wife and I are currently planning a new build together with her parents.
It will be a bungalow with two adjacent residential units (total living area approximately 250 m² (2690 sq ft)).
As beginners in planning, we are now facing some questions that are quite challenging for us, and we are unsure what would be the best solution in the end.

One of these questions is how to design the heating system:
So far, the plan is to use a heat pump with geothermal drilling.
The main question is:
Should there be a single heating system for both units or separate systems for each?

Several people have advised us to choose one heating system for both units, while others recommend keeping them separate.

Therefore, we are very interested in your opinions and, especially, your experiences.

Currently, we have no idea how much the price difference would be between the two options.
Additionally, it is important for us to be able to continue using the unit for her parents.
As we do not have children yet, we would like to possibly rent out the unit later on.
At that point, we will need to be able to clearly separate the energy consumption without requiring a major renovation...

Thank you very much in advance for your opinions and input 🙂

First and foremost: Do you want to build a semi-detached house with separate property plots, or without property subdivision as a condominium with two units to live in with your parents? I strongly recommend opting for separate property plots, as the resale value is significantly higher, and it is usually difficult to market a semi-detached house as a condominium. If you have only one heating system for both houses, you would automatically form a condominium, since separate property plots are not feasible in this case (especially if there is a shared utility room inside the house). That is why I recommend building two completely separate heating systems and utility rooms, and creating separate property plots for the semi-detached house. Otherwise, you would essentially have a nearly inalienable house with two units—unless you are in a major metropolitan area like the greater Munich/Berlin/Hamburg/Frankfurt region. Make sure to install the heating systems separately! Otherwise, you risk ending up with a disputed condominium between two owners, where one can only make changes if the other agrees.

And keep the finances separate. For example, you build one semi-detached house and the parents build the other on the second plot of land; otherwise, this can turn into a family and financial disaster as a building community without any contracts. Sorry for all the warnings, but this is something you really need to know. Building a semi-detached house as a community with four owners on one plot of land is more than just risky. And what happens if both parents pass away at some point? Then you could suddenly end up with almost nothing. Since your wife would then hold 3/4 ownership in the land register and you only 1/4. In case of a divorce, you would have to pay out 75%. With separate houses, each of you owns 50% of the property, and the parents’ house can also be easily sold in the event of a divorce.

Sunshine387 schrieb:

First of all: Do you want to build a semi-detached house with separate property division, or without separate division, as a condominium (owners’ association) in a semi-detached house to live with your parents in two apartments? I strongly recommend having separate property division, as the resale value is significantly higher, and it is usually difficult to market a semi-detached house as a condominium. If you only have one heating system for both houses, you automatically have a condominium, since separate division is not possible in that case (especially if there is a shared utility room in the house). That’s why my recommendation is to definitely install two separate heating systems and utility rooms, and to have separate property division for the semi-detached house. Otherwise, you would essentially have a nearly unsellable house with two apartments, unless it is located in a major metropolitan area like the greater Munich/Berlin/Hamburg/Frankfurt area, etc. Build the heating systems separately! Otherwise, you risk having a problematic condominium with two owners, where one can only make changes if the other agrees.

Thank you very much for your response. Currently, the plan is to proceed without separate property division.
So, accordingly, as a condominium (owners’ association).
Whether separate division would be possible is something we might have to check again.

Special funds of a homeowners’ association can also be sold easily. The issue with this structure is that you might face legal requirements that are more applicable to an apartment building with 30 units rather than a duplex.

If you stay with a condominium ownership structure, I would generally recommend a heating system with billing based on heat meters. Geothermal energy has relatively high fixed costs and isn’t usually cost-effective for a single unit with today’s new construction standards. With two units, it becomes significantly more viable. A possible challenge could be the location of the boiler or heating room and how both units access it. As mentioned, the homeowners’ association concept is typically aimed at multi-family buildings.

In terms of cost, a heating system for two units is certainly more economical. A heat pump (whether air source or geothermal) is not twice as expensive for double the capacity.

Please quickly fill out the completed #questionnaire https://www.hausbau-forum.de/threads/grundriss-planung-unbedingt-vor-beitrag-erstellung-lesen.11714/ and allow yourself to be helped in a connected manner.

Laypersons should seek advice, either in a forum or from professionals. However, they should not try to piece together their knowledge by piecing together a patchwork of individual question threads (or even try to assemble their house based on what has become the winning variant in votes by other laypersons in threads A to Z). There are several experienced contributors here. I myself work nationwide as a building client advisor and am by no means the only one of this kind (others might be regional, but there are such advisors almost everywhere). As a fallback (or best solution), there are also traditionally practicing architects listed in all business directories.

A single residential unit already has several heating circuits, possibly with individual room controls. Consumption meters can also be integrated at multiple points within one system. I do not see 250 square meters (2700 square feet) of heated floor area as a definite reason for a second heat generator. Only in the case of mechanical ventilation with heat recovery should you think twice. Only here is a separation required, regardless of ownership or whether there is a family relationship with the other party.

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