Is KfW 70 worth it in 50 years?

  • Erstellt am 2013-06-17 13:28:31

f-pNo

2013-06-18 13:45:01
  • #1
Hello everyone,

thanks for the information.
At the beginning, I have to point out again my layman status. Therefore, I am not sure whether I have correctly assigned the abbreviations used.
Ht = heating technology
qp = according to Google, could be quality inspection

Of course, I am aware that the KfW requirements are composed of the combination of heating technology and insulation, windows, doors, etc. However, I do not know how the individual factors each affect (except that if you reduce one, you have to strengthen another component to maintain a similar standard – simply put).


We had dealt extensively with the topic beforehand and often read that air-water heat pumps are officially rated down to -15 degrees but often already fail at below -10 degrees. Therefore, although they are cheaper, we decided against these systems.



So far, there is actually no calculation of the heating demand. However, his suggestion of the geothermal heating system (he almost exclusively builds with geothermal) also suited us very well, as we were thinking in the same direction. He gave us one statement on this (I do not have the documents at hand right now, so I can only write it from memory) – he assumes an energy demand of 50 watts per square meter. Thus, we need a pump with 8.5 kW output (if I got it right).
Regardless, his note about "giving up the KfW70 standard" is at first only a suggestion/a thought experiment. The problem is that I unfortunately cannot understand how maintaining the insulation for KfW70 or dropping the standard affects consumption. Accordingly, I cannot really understand the sense or nonsense of this measure. I have now made an appointment with an energy consultant for next week, although I do not know to what extent this appointment will actually be helpful, as it is just a preliminary consultation.



At least the rear wall (in the slope) will be made of reinforced concrete. In addition, a supporting wall will be built centrally here, which in my opinion also consists of reinforced concrete.



We had seven companies do a roadshow. This provider, who made the statement about the significantly underestimated transport/disposal fees, was actually a franchisee. I think we are talking about the same one.
However, we noticed similar statements with almost all providers. We were already slowly despairing. Our idea was a city villa with a basement. However, I already feared back then that we could have problems with groundwater layers, which could make building a basement difficult (white tub).
We got the contact to our construction company by recommendation. Unlike the other companies, no salesperson came here, but a construction engineer. He had looked at the plot before our conversation (the plot is flat at first, then there is a 3 m embankment and then flat again). In addition, since he also suspected the groundwater layer – which was then confirmed by the soil survey – he made us an alternative proposal. We immediately liked this. In our initial ideas, I had also vaguely seen the problem that the terrace would have to be built directly into the slope (= great view), but I never really pursued it further. He recognized this point immediately and solved it by building into the slope (terrace now on the ground floor).
The salespeople never addressed these problems and concerns (although we had partially taken pictures of the plot), but only pursued their sales script. Only when reading the building description did we realize what was missing. Our construction company actually includes most of the additional costs and explicitly points them out to us.

As you can see, I do believe that after a long search we found a reasonable construction partner. But better to ask a little more than too little.

By the way – greetings from the Mosel-Saar region.
f-pNo
 

Bauqualle

2013-06-18 15:53:35
  • #2
... you are absolutely right .. this law is already notorious as a "lobbyist law", there are plenty of articles about it on the internet and hardly anyone takes into account the total financing costs and the operating, maintenance, and repair costs, and furthermore, through the full "thermal packaging" the passive energy is completely left outside and hardly used in the so-called transition phase, additionally there are more and more reports of mold infestation and rot in living spaces and thus health problems .. but I do not want to exaggerate now
 

f-pNo

2013-06-18 23:02:05
  • #3
short update: I emailed our contractor and asked for a calculation of the heating demand. Once with all "components" for Kfw 70 and on the other hand taking into account the changes he offered for consideration. I hope that based on this calculation I can then use the simple basics to find out and estimate from which point such a measure pays off. - I am still grateful for further tips (What is going on with the reply function here today? I can't create paragraphs with Enter and characters I type are constantly missing :mad
 

€uro

2013-06-19 00:05:45
  • #4
Brine heat pump => yes Ht`(W/m²K) => specific transmission heat loss, respectively: Energy Saving Ordinance, KfW requirement value, calculated actual value qp´´ (kWh/m²) specific annual primary energy demand, respectively: Energy Saving Ordinance, KfW requirement value, calculated actual value Both related to AN (fictitious calculation value) Utter nonsense! How does he come to that? Probably a clairvoyant Then you might as well abolish DIN 12831. Maybe that’s not even necessary. Alleged experts have problems with that too. That may be true on the construction side, but that does not make him a KfW optimizer or MEP planner! Best regards
 

Bauexperte

2013-06-20 13:09:44
  • #5
Hello,


A story with sloped roof surfaces is a full story if more than 3/4 of its floor area has a height of 2.30 m. This is usually the case when high knee walls are installed. The exterior appearance often still corresponds to a I-story for the layperson, but mathematically it is a II-story. This is often an annoying issue between sales and the building authority when I-story construction is mandatory.

Rhenish greetings
 

f-pNo

2013-06-24 13:35:37
  • #6


Here I have to correct. We had another discussion over the weekend. The reinforced concrete parts referred to (regarding the styrofoam insulation) are the two reinforced concrete ceilings (basement - ground floor; ground floor - attic).



I had also asked for a calculation of the heating demand based on the hint. Over the weekend, I received a (to me plausible) explanation as to why this has not yet been done.

Since the house in its final form (dimensions, square meters, etc.) was not definitively fixed until last weekend, but changes were still being made, an appropriate calculation could not yet be carried out. From my point of view, understandable – one must know whether to calculate the heating demand for 190 or (now probably final) 170 sqm.
The pre-planned house is now going back to the structural engineer ("final check"). After that, the calculation of heating/energy demand will take place.
Then it should also be clear which measures will actually be taken or not and what impact this will have.

Building such a house is really exciting – especially when, as a layperson, one keeps encountering new points that need to be clarified. Personally, before opening the topic, I assumed that we were actually already close to the building application – with the current checks and calculations as well as possibly resulting changes, I can imagine that it will still take some more time. Exciting but also annoying (I hoped for a July start of construction – well, I can probably forget that).
 

Similar topics
28.02.2013Heat demand calculation according to DIN 1283112
08.01.2014Opinions on the hillside property22
14.01.2014Plot on a slope; embankment - retaining - costs?10
24.03.2014Heating proof: Heat load calculation according to DIN 12831 or DIN 4708?10
14.10.2014KfW70 with gas condensing boiler and solar is definitely not possible21
27.05.2018Slight slope - Should you fill or build on the slope?44
16.12.2018Floor plan design single-family house (city villa 140 sqm) on a slope with double garage495
07.09.2020Trapezoidal plot: Initial ideas / improvement suggestions13
19.04.2020Sloped plot, single-family house 50m², slope, garage optimization41
14.04.2020Steep slope property, please provide an assessment17
08.03.2021Single-family house without a basement on a slope112
27.02.2021Location of city villa or single-family house on a plot with a wide street frontage63
23.12.2023Plot on a slope: first floor plan idea & request for feedback63
08.06.2021Single-family house planning on a slope (2,700 sqm plot) - Experiences / Discussion42
19.08.2021Plot on a slope in the Munich outskirts - how to decide?54
09.02.2022Floor plan: Building on a slight slope - not enough for a basement due to excavation?22
23.03.2022Aligning the house on the plot: North-South / East-West, what should be considered?42
28.04.2022Catch a 2-meter slope, L-shaped stones, dry wall or other ideas?22
18.02.2023Floor plan - plot for a single-family house, slight slope approx. 175m²67
03.08.2025South-facing plot 700 sqm, single-family house approx. 150 sqm, any ideas or input?43

Oben