ᐅ Analytical Evaluation of Different Energy Concepts

klblb schrieb:
That’s how we build as well, but we will even achieve below KfW40 standard. A well-insulated building envelope is a one-time investment that immediately provides continuous energy savings. There are no maintenance requirements or costly replacements needed, like with a heat pump, for example.

When it comes to windows, the price is driven much more by the material (e.g., wood-aluminum vs. PVC) than by the thermal insulation properties (double glazing vs. triple glazing).
The same applies to masonry: expensive Poroton blocks and more affordable Twinstone or Gisoton can offer the same thermal insulation values, but Poroton uses the classic red bricks. You need to weigh up what is more important to you.

It is perfectly possible to build well insulated at a relatively low cost.

With these kind of 'combi blocks,' I think caution is advised!

Poroton comes with either perlite (good) or mineral wool (MW, which I would avoid). Twinstone is an aerated concrete block (if I’m not mistaken), similar to the Yong system. From an ecological and building biology perspective, aerated concrete blocks and Poroton with perlite are certainly considered good. Gisoton, on the other hand, has a foam filling, which I would avoid.

Besides the price, there are other decision criteria worth considering.

A filling made of mineral wool or foam will definitely limit vapor diffusion through the masonry (though if the interior walls are painted with dispersion paint, it doesn’t really matter anyway).

Regarding aerated concrete blocks, I have heard disadvantages related to sound insulation (you hear a lot from the street, or vice versa) and mechanical fastening of objects to the wall (e.g., screwing), but I have no practical experience with this!

Best regards

K.Brodbeck

There are plenty of comparisons available... just search for something like "gas heat pump cost comparison" and you will find various forecasts...

Due to the high initial investment costs, heat pumps are generally ranked lower...

@K.Brodbeck

Of course, price isn’t everything! I completely agree!
I share your ecological, building physics, and building biology assessment of the three materials (Poroton, Twinstone, Gisoton).
Sound insulation always needs to be evaluated on a case-by-case basis. Regarding attaching items to the wall with screws, I haven’t heard of any restrictions with aerated concrete so far.

Hello,

kirsel schrieb:

What do I need to conduct a proper energy assessment? Which key data do I need from my planned single-family house? Are there example calculators online to roughly estimate this? Or can this only be done by an (expensive) energy consultant?

I’ll start from the end...

I find it hard to understand that homeowners like you are willing to invest a lot of money to realize their dream of owning a home. Yet, at the same time, the vast majority of self-builders share the tendency to “save” money in significant areas, preferring to reserve funds for extras in the interior fittings. A good energy consultant (provided this service is not offered by your preferred, reputable supplier) — characterized by proper training rather than just a certificate for attending a short 3-hour seminar — costs between 1,000 and 3,000 EUR (approx. 1,100 to 3,300 USD) depending on the scope of the assignment and the size of the building project. This is very well-invested money if it eventually leads to an economically sensible decision. Even in energy consulting, there is no “one-size-fits-all” solution; every building project needs to be considered individually.

I also notice this tendency myself as a moderator here on the HBF. Depending on my time availability, I try to answer questions within my area of expertise as well as possible. Still, almost every week there are jokers who expect me to evaluate their entire building documentation free of charge just because I conveniently provide information on the HBF for everyone. For an investment mostly exceeding 300,000 EUR (approx. 330,000 USD) per building project, I can only shake my head that some try to “save” a few hundred euros this way at my expense, so that there’s more budget left for a premium washbasin or whatever else for mom...

For you, this means — regardless that this topic has already been discussed many times on the HBF and reading helps — that you should place your trust in a serious sales advisor you trust, arrange a meeting with the regional energy agency (such as the Energy Agency NRW), or consult a trained energy consultant. In my opinion, you do not have the required knowledge to make this decision alone and without expert support. And if it costs you money, that is only fair — every service requires payment. The important thing is that it leads you to your goal. Some extras in the fittings can also be added over the years.

kirsel schrieb:

The type of heating concept, renewable shares, etc., is a calculation task, clear so far. We would also prefer to work with a ground source heat pump and support it with hot water. However, it makes no sense if it only pays off after 30 years, and the heating system then almost needs to be replaced again.

Why do you want to install a ground source heat pump in particular? Maybe it isn’t economically sensible for your building project because the soil conditions do not allow it at all?

Why do you calculate with 30 years? A current gas condensing boiler typically lasts about 15 years +/- because its technology produces condensate.

Perhaps an air-to-water heat pump would be the exactly right solution for your building project — or do you believe the statements of laymen that your electric meter will explode?

There are many ways to Rome. Which technology is ultimately the most economically sensible decision for your building project cannot be limited solely to the question of payback period. As stated repeatedly, no building project is comparable to another.

Best regards, Bauexperte

Hello,

K.Brodbeck schrieb:

I have heard some disadvantages of aerated concrete regarding sound insulation (you can hear a lot from the street, or vice versa) and the mechanical fastening of objects to the wall (screwing), but I have no practical experience with it!

With 36.5cm (14.4 inches) walls and thicker, sound insulation is no longer an issue; special anchors are needed for almost every type of masonry. A common joke among sales colleagues is, for example, to always have quick-setting mortar on hand when working with hollow bricks.

As good as it gets – everything has its pros and cons.

Best regards, Bauexperte

Hello,

Bauexperte schrieb:
....There are many ways to reach Rome. Which method is ultimately the most economically reasonable decision for your construction project cannot be determined solely by the question of payback period. As repeatedly mentioned, no construction project is comparable to another...

Correct. However, heating systems never have a payback period, as they always produce losses, never profits! Perhaps it is time to move away from this terminology in this field!

Best regards