ᐅ What is currently the best heating system?

Saruss schrieb:
.... Ultimately, these are all just theories; to make a concrete statement, you probably need a specific construction project with all the details.

Correct, you hit the nail on the head!

Best regards

PS: Hello €uro )
__

A few comments on this.

Two of the most important factors for efficient heating of a house:

1. The house should have as low heat loss as possible, because if no heat is lost, you don’t need to spend much on reheating.
Here, "KfW55" is already a minimum standard (although it can be interpreted loosely)... I would recommend going even better (KfW40, Passive House).

2. The heating demand and maximum required heating capacity for the house (and the occupants) must be determined with sufficient accuracy. You can’t rely on rough estimates from the builder!

Only when these points are addressed can you proceed to selecting/determining the appropriate heating system.
This includes not only the heat generator but also the heat distribution (e.g., underfloor heating) and the entire system (domestic hot water, distribution, storage, etc.).

A few other things overheard here:

- Single-layer solid construction (without additional external insulation)
This usually does not result in low heat loss or low heating costs.
It is “cheap” to build (if you don’t get scammed), and that’s about it.
The savings are quickly used up, and the insulating value of the wall affects the house for its entire lifespan...

- There is plenty of wood in Germany.
That’s nonsense. Everyone relies on wood: heating systems, home builders, furniture industry, paper industry, and much more... even plastics are made from it.
Wood is already partly imported today; otherwise, our “huge wood stocks” would have long since diminished.

- Air source heat pump as a cure-all
Where it suits the building, the occupants, and the climate region, the air source heat pump can certainly be the first choice.
Unfortunately, these factors are often overlooked, which does not help the reputation of air source heat pumps (and heat pumps in general).
The air source heat pump can quickly result in relatively high consumption costs if the conditions are not right.
It’s basically like the solid wall without additional insulation mentioned above: eventually, the initial savings are used up (even faster with rising energy prices), and the air source heat pump no longer proves to be the first choice.

- Oil and pellets
For me, these are no longer an option in single-family house construction.
Pellets may only make sense when heating multiple houses together (i.e., a large system) or as automatic supplementary heating, e.g., for peak loads (individual stove or integrated into the heating system).

- Ground source and air source heat pumps
Both should always be considered, with the air source pump approached more critically.

- Gas
If someone simply wants the cheapest solution without investing in the future, gas could be an alternative.

- Solar thermal
Small systems for domestic hot water are hardly economical—mostly interesting only for meeting energy saving regulations/planning permission/KfW standards.
When combined with heat pumps, solar thermal is consistently unprofitable.
Often advantageous combined with wood or pellets.
Especially beneficial for high hot water demand in summer (e.g., pools).
Very large solar thermal systems that cover about 70-80% of total heating demand can be ecologically and potentially economically very good, though initial costs are very high.

- Photovoltaics
A photovoltaic system is not heating; it is a power plant.
It should always be considered separately from the heating system—like an investment.

Regards
-Martin-

Very interesting points.
In summary, one should use an air source heat pump powered by electricity from a photovoltaic system. That way, heating is almost cost-neutral.

Häuslebauer40 schrieb:
In summary, it is advisable to choose an air-source heat pump and power it with electricity from a photovoltaic system. This way, heating can be almost cost-neutral.

It’s great that all of you energy savers primarily focus on operating costs. However, there are some builders who have to work within a limited budget for the investment costs.

At least for me, terms like payback period, profitability, depreciation, debt service, and interest are also important. This already starts with the question of whether a filled, porous high-porosity brick T8 will ever pay off compared to an unfilled T10. (Approx. 5 kWh/year additional consumption per square meter for about 240 square meters for a townhouse with 160 square meters = 1200 kWh/year = about €85/year for gas). Or whether the extra €10,000 to €20,000 for a heat pump will ever be worthwhile over its lifetime, and so on and so forth...

Do I really need a specialized energy consultant for this evaluation, or should such a consultant only be involved when it comes to optimizing the technical details?

Häuslebauer40 schrieb:
Very interesting points.
In summary, you should use an air source heat pump powered by electricity from a photovoltaic system. Then you heat your home almost cost-neutrally.

No. That is too simplistic and somewhat misleading.

You should operate the heating system that results in the lowest total costs over the long term (at least 15 years) compared to other options, while also considering ecological impacts.
This includes investment and operating costs, but also financing costs, expenses for risk coverage, and so on. When forecasting costs, it is reasonable to account for unfavorable scenarios (for example, very high energy prices), since you still have to pay even in such cases.

If you insist on considering photovoltaic together with the heating system:
What is the point of a photovoltaic system that yields, say, a 5% return, if at the same time you choose a heating system that increases consumption by 30-40%?

Heating is cost-neutral only if the photovoltaic system generates enough electricity to pay for itself and additionally produces a sufficient amount of power for the heating system.
However, such a large system will not fit on a typical single-family home.

@o.s.

Your approach regarding the factors for the calculation is basically good.
But after that, you fall into simplistic assumptions.
(By the way, where do the 5 kWh/year of additional consumption come from?)

A better U-value does not simply affect the energy demand in a directly proportional way.
There are also effects such as smaller heating systems, the possibility of other heating types, more favorable parameters (e.g. lower supply temperatures), and so on.
Also, a wall surface temperature close to the indoor air temperature is an effect that, once you know it, you hardly want to miss anymore.

Actually, you should not only consider the heating system as a whole but look at the house, the heating system, and the occupants together.
It is perfectly reasonable to comparatively include different wall constructions (etc.) in this.

If you do not just switch from T8 to T10, but actually build the walls as concrete slabs, you save even more on investment.
Then add wood and oil stoves (if this complies with the energy saving regulations / building codes) – you can’t get cheaper than that.
Just be careful that your wife doesn’t run away from that... then the calculation no longer works out.

An energy consultant can only support you in the overall concept. And that is not a bad thing.

For optimal technical planning, however, you need a planner specialized in technical building equipment / building services engineering. The energy consultant cannot and does not do that.

And if you are really concerned about the investment amount, then you should question the house size and the construction method.
Perhaps independent and/or professional advice can help you achieve more on less space or find a construction method that offers good thermal insulation at a reasonable price (think of sand-lime brick plus external thermal insulation composite system / ETICS, or possibly timber construction).

Again:
You want to build “only with T10” — completely without additional thermal insulation?
Then you could also buy a house from the mid-1990s; you wouldn’t have to build new, because back then you would have gotten such a house for significantly less money than a new build including additional costs.

I strongly advise everyone against building with no or only minimal thermal insulation!