Which heating system for a newly built single-family house in 2011?

After we made progress with our efforts to secure a building plot, we are now facing the problem of choosing the right heating system. The representative of Fa. Ambiente Massivhaus said that only once the plot and house are finalized will he carry out a heating surface calculation and heat demand calculation (or whatever it is called). A underfloor heating system will definitely be installed. He recommends an air heat pump system with direct evaporator. The residential area is connected to natural gas.

Now my question: when I read all this, there is no compelling reason to install an air heat pump. Very low performance in winter (maybe global warming will still come), poor annual performance factor compared to surface collectors and probes, and high noise levels due to massive air circulation. In addition, high electricity costs in winter due to auxiliary heater/heating rod. The aforementioned alternatives would be better in this regard. But such a heat pump with surface collectors also costs significantly more, mainly because of the earthworks. Our house will have a living area of about 125-130 m2 (1.5 stories), so approximately 260 m2 of surface would be needed. This would be available on the plot. What would something like that roughly cost? So excavation/earthworks etc.

Furthermore, I am considering heating with gas, i.e. installing a gas condensing boiler. Plus hot water preparation on the roof. That would be quite inexpensive at first. Since today’s houses are all well insulated (Energy Saving Ordinance 2009), and a condensing boiler can heat very efficiently compared to older systems, the heating costs should be manageable, right? I mean, hot water is heated by the sun for 3/4 of the year and thus does not need gas, the house is well insulated and the burner is economical... three factors in favor. Or am I completely wrong about that?

In 10 years or later, one could still switch from gas to whatever.

Hello,

...The representative of the company Ambiente Massivhaus said that only when the plot and house are finalized will he carry out a heating surface calculation and heating demand calculation (or whatever it is called).

At least it’s commendable that he intends to do this. I would like to check the result sometime. ;)

...
He recommends an air heat pump system with direct evaporator. The residential area was connected with natural gas.

How can he recommend that when the necessary parameters have not yet been calculated? ;)
Well, just a salesman!

...The aforementioned alternatives would be better.

Believing, assuming, and guessing is one thing. I would not make any considerable investment based on that!

...But such a heat pump with surface collectors also costs significantly more, partly because of the earthworks.

Correct, every source tapping costs significantly more than air! That’s why people like to save here to minimize costs as much as possible. The builder will be the one who loses out later. By the way, DVs have their peculiarities, which is why they are also little used.

...What would something like that roughly cost? Like earthworks/excavation, etc.

That cannot be reliably answered because the decisive parameters are unknown. What does the general contractor/ main contractor offer compared to xy?

...
Besides, I am considering heating with gas, i.e. installing a gas condensing boiler. ...Or am I completely mistaken?

No, not completely. In my cost-effectiveness calculations, gas condensing boilers and air heat pumps often run neck and neck when considering only heating operation and hot water preparation. The decisive factor here are the respective concrete numbers.
However, gas condensing loses considerable ground when room temperatures/cooling loads during the summer heat period are so high that the removal of heat (cooling load) must be considered. Here gas offers no alternatives.
The reason is that the Energy Saving Ordinance primarily treats heating operation/hot water preparation in terms of primary energy, while summer thermal protection is severely neglected. This leads to higher room temperatures, especially in the attic, so that removal of heat becomes necessary. Controlled residential ventilation is mostly not suitable for this!
A tip: Have the room temperatures/cooling loads during the summer heat period calculated. (VDI 2078 computer method)
Have the results guaranteed in the contract with appropriate sanctions for non-compliance. ;)
At the latest here your salesman will start to fidget nervously in his chair!

...
In 10 years or later, you could still switch from gas to something else.

Subsequent changes are usually considerably more expensive, unless the system is designed and prepared for this. Then you might as well do it right away.

Best regards

Hello,

Now my question: when I read all this, there is no compelling reason to install an air heat pump. Very low performance in winter (maybe global warming will still come), poor annual performance factor compared to surface collectors and probes,

You are under a misconception, which many builders make, by putting energy efficiency before the expected costs – initially, the annual consumption is what matters?

It is true that the annual performance factor of geothermal or surface collectors shows better yields on paper; however, this is countered by the high installation costs; depending on soil conditions and number of drillings, in the five-figure range. With surface collectors, you can only use your garden as an English lawn, nothing more. You should also consider how long you want to heat before the invested costs pay off.

and high noise development due to massive air circulation.

With all due respect, that is nonsense, the outdoor unit of an air-water heat pump is not a high-performance turbine, it only starts up when there is actual demand and is not louder than normal conversation volume, if at all.

Additionally, high electricity costs in winter due to supplementary heater/heating element. The aforementioned alternatives would be better.

No heating system works _without_ electricity, that first. The still young experience with these heating technologies has shown that heating costs are in the range of €600-800/year, depending on the heating and showering behavior of the users. Due to last winter, costs are likely to have increased by about €50-100, but this is also the case with any other heating system.

In 10 years or later one could still switch from gas to whatever.

It cannot be denied that gas currently offers the most favorable price/performance ratio overall; however, with a condensing boiler you buy a system with about 5 years shorter service life (ask a sanitary company you trust). Conclusion: fair and overall viewed, an equal number of advantages and disadvantages speak for the currently available heating systems on the market.

Nevertheless, if you want to be on the safe side, you should consider installing a gas condensing boiler. There are currently many innovations under development in the alternative heating energy sector, all of which can be connected to the underfloor heating system. For example, pilot projects are running in Bavaria with small wind turbines mounted on the roof of single-family houses; a system – in my opinion in the Eifel – where surface collectors are being extensively tested; as well as a system with fuel cells for later use in single-family house areas – in my opinion sponsored by VW.

What you should consider is that the installation shaft in your new building – which houses the installation lines – leaves enough space so that future technologies, as described above, can be accommodated when the service life of the condensing boiler comes to an end.

Regards
Construction expert

Thank you for your valuable assessments. So one shouldn’t view the air/water heat pump so critically? Despite expensive supplementary heating in winter, it pays off in most cases?

@€uro: the weak point is the lack of cooling option in summer, ok. But couldn’t one just open the windows like today, right? Do the rooms heat up so tremendously due to solar radiation?

We have an old clay house at home with certainly 60cm thick walls. It stays warm in winter and cool in summer, precisely because of the good insulation. Is that no longer the case with today’s also well-insulated walls? So, air conditioning is mandatory?

Can hot water preparation on the roof be combined with an air heat pump? That would be good, then one would certainly need to draw in significantly less air heat if the water heating was omitted.

Hello,

Thank you for your valuable assessments. So, one shouldn’t view the air/water heat pump so critically? Despite expensive additional heating in winter, it is economically viable in most cases?

Basically, everything should be viewed critically, because every solution unfortunately has both advantages and disadvantages. There is no universal best solution that fits every situation, although salespeople like to claim that.
Whether or how much additional heating is needed in winter depends on a number of object-specific parameters. Air heat pumps have partly gotten a bad reputation because in practice the forecasted values were not achieved. This is partly due to the manufacturers, but in most cases it is due to the system installers. They do not dimension and calculate as necessary but estimate, assume, and speculate. The result is a low-efficiency system.
Example: A defined climate location: From the design point e.g. -14 °C to about -4 °C, only about 6% of the total annual heating energy is required. If a small amount of electricity e.g. via an electric heating element, if that is even necessary, is included here, that makes relatively little difference in the overall annual balance.

@€uro: so the weak point is the lack of cooling option in summer, okay. But couldn’t one simply open the windows as is done today and be fine? Do the rooms really heat up so much from solar radiation?

Weak point with gas, yes, but only if cooling is necessary – otherwise not!
Window ventilation might work, but it only suffices if a sufficient cooling potential from the outside air is available on the one hand and if there are low cooling loads from the building on the other hand. This mostly applies during the night and early morning hours. Not every location is suitable for this (e.g. noise, dust, pollen, etc.). Who ventilates during vacation? The room temperatures fluctuate, and interior storage masses (walls, floor slabs) absorb this energy. With window ventilation, hardly any effect can be achieved, especially if the outside temperature is near or above 20 °C.

...We have an old clay house at home where we live with certainly 60 cm walls. It stays warm in winter and cool in summer, precisely because of the good insulation.

That is not due to good insulation but to the storage mass. Insulation is primarily beneficial for winter thermal protection. During the summer heat period, the radiation portion of the sun on the building components is decisive; the insulation effect plays hardly any role. Modern buildings lack this mass.
An example: Old churches or even cowsheds with 40 to 50 cm thick walls made of field stones have very poor insulation values. However, they are pleasantly cool in summer – how is that?

...Is that no longer the case with today’s well-insulated walls?

The new Energy Saving Ordinance for buildings is "tuned" for winter thermal protection.

...So air conditioning is mandatory?

No, not mandatory. It does not have to be air conditioning right away. You have to know the building’s cooling load; only then can it be said if and what measures are necessary.

...Can domestic hot water preparation on the roof be combined with an air heat pump?

Yes, it can.

...That would be good, then one would certainly have to significantly suck in less air if water heating were eliminated.

“Significantly” would have to be defined. I would say that one can harvest some kWh with a solar thermal system. Whether that is economical is another matter.
“Suck in”??? I am not talking about an air-to-air heat pump! That would be a completely different topic.

Best regards.