ᐅ Assessment of Heating System Upgrade Costs

Hello!

We are currently planning our single-family house (~145m² (1,560 sq ft) plus basement) and are now completely confused about the heating system! Almost everyone who wants to build a house for us says something different. It ranges from "I would never build without a heat pump and mechanical ventilation with heat recovery" to "everything other than gas is nonsense, way too inefficient!" to "What, KfW70? Why would you spend money on that?"

I understand the inefficiency at really low temperatures, but if it’s not -15°C (5°F) cold, it should work pretty well, right?

While researching, I came across hybrid heating systems that automatically use a gas boiler as backup when the heat pump’s efficiency is too low. As a layperson, that sounds like a good idea to me. What do you think? Of course, compared to a pure heat pump, I’d still have to pay for the gas connection, but as an alternative to a gas-only heating system…?

In general, I also liked the idea of a ground-source heat pump, but since we have a slight slope, some have ruled that out from the start.

Thanks in advance!

Hello,

Yes, we also spent a long time considering the heating system... 😉

In the end, we decided on an air-to-water heat pump combined with a central ventilation system featuring heat recovery.

If it actually gets very cold, we will need to use the integrated electric heating element as a supplement. However, our electricity demand will be easily covered by the photovoltaic system on our roof. Our soapstone stove will also contribute to keeping the house comfortably warm.

My brother has been living in his house with almost identical technology for three years now (different manufacturer, but the basic concept is the same), and he even earns a few hundred dollars every year from his photovoltaic system, although there have been winter days when the electric heating element was also in use.

If you don’t already have gas connected in your home, I would personally invest the money for a gas connection into a photovoltaic system instead – which you will benefit from more in summer, too.

However, it is very important that you choose a heat pump tailored to your specific requirements. An oversized or undersized system will only cost you unnecessary money or reduce comfort...

Regards,

Dirk

Hi!

Maybe a zeolite gas heat pump could be something for you.
It's really interesting.

Regards
Sebastian

Hello,

tlactar schrieb:
....Almost everyone who wants to build a house for us says something different.....

That is the nature of things and makes it extremely difficult for homebuilders to make the right decision.
You should never take advice from someone who is also selling and/or installing at the same time, but always from an independent, sales-neutral expert!
The content of polished, colorful advertisements is mostly never reflected in the contract details.

tlactar schrieb:
....It ranges from "I would never build without a heat pump and ventilation with heat recovery" to "Oh, anything other than gas is nonsense, far too inefficient!" to "What, KFW70? Why would you want to spend money on that?"....

This adequately characterizes the current situation. No construction project is the same as another, even if the building is identical, because the influencing factors are extremely diverse and highly differentiated.
Without a solid and precise basic assessment, you will not find an economical solution here.
Also, when evaluating opinions online, one should be quite critical. Most advisors are anonymous, have no formal training, and do not have to assume any liability, etc.
Individual experiences from homeowners are certainly very interesting, but not transferable to other construction projects!!!

tlactar schrieb:
...The inefficiency at really low temperatures makes sense to me, ....

Well-designed air source heat pump systems can reach an annual performance factor of around 3.5, provided everything fits and works well together.
At low outdoor temperatures, the actually usable energy content of the outside air is indeed lower, but how many % of the annual heating energy demand does this represent? For example:

This obviously depends on the specific climate location. I always use this data in my planning!
In well-sized systems, the share of a supplemental electric heating element is just < 1% of the annual heating energy demand. Negligible in the overall context!
Fully modulating split units are the top choice here!

tlactar schrieb:
...Sounds like a good idea to me as a layman. What do you think? ...

Combo units can be found in nearly all areas (heat generators, storage...). Although they are compact, they generally represent a modest compromise. Rarely economical overall.

tlactar schrieb:
..., but as an alternative to pure gas heating...?

Neither fish nor fowl. Based on the results of an exact and solid initial assessment, the appropriate solution can be easily found.

tlactar schrieb:
...In general, I would have liked a brine-water heat pump, but because we have a slight slope, some have ruled it out from the outset...

Whether the opinions of some are actually economically reliable enough to make a significant investment decision, I would not suspect ;-)
There would still be many other possibilities.

Best regards.

Doc.Schnaggls schrieb:
..... My brother has been living in his house for three years with almost identical technology (different manufacturer, but the basic concept is the same), and he even earns a few hundred euros each year with his photovoltaic system, although he has had days in winter when the electric heating element was also in use...

I have already planned and sized this basic concept several times with both ground-source heat pumps and air-source heat pumps. Heating, hot water, ventilation, cooling, cooking... can sometimes be achieved at net zero cost, and sometimes there is even a small surplus of a few euros! Of course, the investment cost for the photovoltaic system is additional. Usually, though, it is not a problem. As always, => individual case assessment! Unfortunately, mistakes are sometimes made in preliminary evaluations here as well. The decisive factor is always the annual energy balance, not the single result on January 15 of any given year!

Best regards

Hello Dirk,

Doc.Schnaggls schrieb:

Well, if it really gets too cold, we will also have to use the integrated electric heating element to heat.

You have me puzzled... why would you need to use the integrated heating element, which is only intended to defrost the outdoor unit in freezing conditions?

Regards, Bauexperte