ᐅ Heating / New Single-Family Home Construction / Which Options Make Sense / Costs and Benefits Over 20 Years

Hello... we are about to start building a simple single-family house with 140 sqm (1,507 sq ft) of living space and KfW 70 standard, heat recovery through the ventilation system, windows with 0.5 glazing, etc. Now we are facing the decision of which heating system to install. The options are natural gas with solar support for domestic hot water, natural gas with solar support for both domestic hot water and heating, an air-to-water heat pump (possibly combined with solar support), or a ground-source heat pump with horizontal collectors.

Regarding initial costs, it doesn’t really matter to us since we have sufficient funds. For gas, for example, a lot of piping would be required (30 meters / 98 feet), and for the generally more expensive ground-source heat pump, the earthworks. What matters most to us is what pays off in the long term. It is important that we have a system for the next 10 to 20 years and don’t end up paying more after 10 years for a cheap system due to high running costs. Of course, maintenance is also a factor. According to the heating engineer, a gas system may fail after 15 to 20 years, which is not a big problem, but then the question is whether getting a new gas system would be more worthwhile than, for example, a ground-source heat pump that is supposed to last 30 years.

Also, the question of energy costs: the heat pump runs on electricity (assuming normal household electricity since I don’t believe special tariffs will last forever and that phasing out nuclear power will cause quite a shock to electricity prices). Is it cheaper than a gas system? Of course, neither I nor anyone else knows what electricity and gas will cost in 10 to 20 years. However, most people agree that electricity prices will rise more than gas prices.

Then there is the topic of solar power: the difference between support for domestic hot water and support for both domestic hot water and heating is quite significant. But will it really pay off? I find it very difficult to decide which system or combination makes the most sense.

Hello,

Nordlichtchen schrieb:
... Now we are facing the decision of which heating system to install. Options include natural gas with solar support for domestic hot water, natural gas with solar support for both domestic hot water and heating, an air-to-water heat pump (possibly combined with solar support), or a ground source heat pump with surface collectors... As for the initial costs, it all comes down to about the same since we have enough budget available,...

Even if the budget is sufficient, that does not mean you should necessarily choose an uneconomical solution.

Nordlichtchen schrieb:
... Our concern is what will pay off in the long term? It is important to us to have a system that lasts 10 to 20 years and not pay more after 10 years for a cheap system due to high running costs.

Correct, there is no better approach!

Nordlichtchen schrieb:
... I find it really difficult to decide which system or combination makes sense

Correct, without a solid basic assessment, it is not possible if you want to rely on reliable data. First, the actual demand (capacity, energy) for heating, hot water, and possibly ventilation of the building is determined based on the building parameters, climate location, and user behavior. Based on this, combined with various technical solutions, the expected consumption can be estimated.
With these consumption figures, the related investments, or capital costs, can be evaluated reliably.
Without concrete numbers, it means guessing, assuming, or estimating—i.e., speculating!

Not a suitable basis for a major and long-term investment decision.

Best regards.

And actual consumption, unfortunately, changes over time... For example, in our case, the two children’s bedrooms were barely heated while they were babies or toddlers, because an optimal sleeping temperature of 18°C (64°F) only triggered the heating on extremely cold days in those rooms. However, as the children grew older and the rooms were no longer used for sleeping (our bedroom, for example, is not heated at all), but rather as living spaces for homework and daily use as teenage bedrooms, much more heating was used. Room temperatures of 21–23°C (70–73°F) are a different matter entirely, and that causes the “theoretical” calculation by the energy consultant to fall apart, since this scenario was not considered or included in any alternative model.

Therefore, no theory can give you clear certainty—at best, it can provide a rough indication or direction. Also, if you heat your living room differently than calculated, or if you use the predicted fireplace stove differently—or not at all—things will look different again.

As a decision support tool, using several models to narrow down to two and then choosing between them to find a general direction can certainly be helpful. However, such analyses are usually costly and time-consuming, especially given current trends, so it’s a good idea to ask in advance about the cost and consider whether you want to invest that money, which will have to be earned back in the long run.

Personally (and this is just my opinion, not advice or anything similar), I recommend talking to the heating installer you trust, or even several, because they have daily practical experience and their advice has worked very well for everyone else in our building area. They know all this from practice and deal with all kinds of situations every day, so they can give you recommendations based not only on theoretical computer calculations but also on real costs and effects. Our energy consultant was also our heating technician, so the money invested was offset against the contract. Most people in our area have followed the advice of their heating technicians, and I have to say, in similar buildings the same systems are used and none of them stand out with unusually high running costs or investments. Of course, it might be different elsewhere, and there may be some who only install what requires them the least work or yields the highest profit.

Ultimately, what you decide is entirely your own choice.

Philiboy83 schrieb:
...since then, much more heating has been used there; maintaining an indoor temperature of 21-23 degrees Celsius (70-73°F) is quite a different matter, and this causes the "theoretical" calculation by the energy consultant to fall apart, since it was not taken into account or included in any alternative model.

Why not? Any "contingencies" can be considered. Anyone who doesn’t realize that toddlers eventually become teenagers has probably made a mistake.
However, an energy consultant is often overwhelmed by this, unless they are also an HVAC (Heating, Ventilation, and Air Conditioning) planner.

Philiboy83 schrieb:
...But usually, it’s not offered for peanuts because it is very time-consuming and, due to current trends, likely to be priced expensively, so you should ask beforehand what it costs to consider whether you want to invest that money, which then also needs to be earned back...

Economic feasibility is always important, which is why a solid basic assessment is so essential.

Philiboy83 schrieb:
...Personally (and this is only my personal opinion, not advice or anything similar), I talk to the heating installer you trust or to several, because they have daily practical experience, and this has worked really well for everyone else in our building area.

Almost any heating system will make a space warm; very few are actually efficient. In other forums, there are plenty of examples where this trust has often been severely disappointed, as it is usually not part of the contract with the installer. Mostly, what is sold is only superficial. Often, systems are installed without sufficient planning. Most operators don’t even realize that consumption is actually too high! How could they, when a real basis for comparison is completely missing.

Philiboy83 schrieb:
...They know everything from practical experience and deal with all kinds of situations daily; they can give you not only theoretical advice on a computer or tell you what costs what...

From practical experience, I could report to you, especially about the many poorly executed systems that were inadequately sized.

Philiboy83 schrieb:
...and I must say, in similar buildings, the same systems are used and none stand out with unusual running costs or investments...

That is very unlikely, since the buildings, technical equipment, and user behavior would have to be completely identical!

Regards

€uro schrieb:

Completely unlikely, because the buildings, system technology, and user behavior would have to be exactly the same!

v.g.

I would rather question that more carefully instead of immediately labeling it as "completely" unlikely. Maybe he meant something quite different than how it was understood (which is always a problem with written communication—who understands what and how). I don't think he means that they are all the same houses with the same users and the same heat demand, but rather that they have the same system in different houses with different occupants and, for example, receive approximately the same amount of heat output from one kWh of electricity or from one cubic meter of gas, or whatever fuel is involved (nothing is specified). I understand it as meaning that, for example, with two houses that have the same system, one does not operate extremely cheaply and the other extremely expensively (when converted to heating and energy demand or however you want to call it), but rather that both are very close in cost.

Why would he write something untrue, or why would neighbors, friends, or whoever else have lied to him if he discussed it with them?

Regarding the actual topic: If the architect is going to do the exact calculation for the actual demand, he wants 1,000 euros, and with that calculation I can then go to the heating installer or whoever and have them provide estimates of costs and operating expenses.
Hmm, 1,000 euros is quite a lot of money... I'm not sure yet if I want to afford that just to save around 5 euros per year overall...

Currently, we have brought in three heating installers and will first see what they say and suggest, and base our opinion on experience.

By the way, we could also use district heating, but with a 400-euro annual base fee (without even using any heat yet), connection and installation costs of 15,000 euros, a 10-year contract, and a "Polish fleet" that has already done poor work with excavators at two other neighbors, that option is off the table.

Hello,

If you already have plumbers available, I would also ask them if they can prepare a heating load calculation, because they need some basis for selecting the size of the system. Having the plumber do this is often more cost-effective than having an architect do it, since architects usually charge more for these additional services.

And even if the plumbers do not want to do the calculation, I would at least ask them to explain in detail the basis on which they selected the heating system—especially regarding the size and modulation range (i.e., from/to kW)—so that you don’t end up comparing two completely different systems when different capacity sizes are offered.

Best regards
Erik