kfw40plus monolithic solid - tips/experience?

  • Erstellt am 2016-03-08 17:25:54

Bauexperte

2016-03-11 10:47:28
  • #1
Hello,


That is true and also wrong at the same time; a construction contractor must provide you with an offer according to Kfw 40; the architect must provide an appropriate cost estimate. With what masonry – in centimeters – was the building permit granted?

You should have simultaneously consulted a system planner regarding photovoltaic and storage technology. He needs all relevant data about the planned construction project and especially the information about the heat demand. Afterwards, he can provide you with a precise fixed-price offer – end of calculation.

In our case, photovoltaic systems are – for various reasons – also not included in the scope of delivery of the cost estimate. The most important reason here is that it needs someone who knows what he is doing _and_ can be held liable in the event that KfW 40+ cannot be achieved, although the building envelope is prepared. We act *only* as intermediaries because we simply lack the expertise for exact dimensioning; however, we rely on long-standing partners. Personally, I am against *jack-of-all-trades* – either nothing would be done properly or I would have to work with your current status quo. Not my thing; everyone should do what they do best!


Planning a KfW 40+ from scratch is quite elaborate; you want to move an existing photovoltaic system with fixed consumers. That requires quite some calculations; the offered price fits for me.

There is – for cost determination – the way I described at the beginning. Then you at least have the figure for KfW 40 on the table and afterwards still need an offer from a system planner for moving the photovoltaic system. After that or simultaneously an energy consultant must calculate again, of course. In any case, quite a few euros will probably flow before you know whether everything works as you hope.

Greetings from the Rhineland
 

bellamuc

2016-03-11 10:54:36
  • #2
A 42.5 cm wall would not be a problem considering the size of the house. That would be great. With which stone could that be done? I am told that if at all, it would only be possible with the 0.07 version and the stones break in the hand and have to be reinforced with effort, and the reinforcement, together with the higher price for the 0.07 version, would cost so much more that it wouldn't be worth it.
 

bellamuc

2016-03-11 11:01:51
  • #3
I don’t understand why you are placing so much emphasis on photovoltaics? I am a photovoltaic project planner. What is so problematic about it? There is more than enough energy available, it covers the entire electricity demand of the 3 residential units and even the 2 electric cars. For poor, sun-poor winter periods (> 2 weeks), electricity might need to be purchased – but until the house is built, there is swarm energy with the wind power being stored in between. It’s not that complicated.

However, I do not know how photovoltaics are incorporated into the kfw calculation.

At the time the input BA was made, I couldn’t commission a specialist planner – there are other reasons for this, and it is a long issue that I would like to omit here.

The fact is that the building permit has been granted (with 36.5er), the financing is in place, and construction is to begin now. However, I would like to be able to weigh whether and to what extent I can achieve the kfw40+ guidelines. And preferably without having to commit contractually beforehand or spend money to calculate an offer.
 

Bauexperte

2016-03-11 11:02:17
  • #4
Normally with a stone with a lambda value of 0.07 (W/mK), this results in a U-value of 0.16 (W/m2K). It does not matter whether an aerated concrete or a hollow brick with internal insulation is chosen.

Aerated concrete is easier to work with, with the filled stone it is somewhat more complicated, but not unsolvable, since the internal insulation becomes loose during cutting.

Rheinische Grüße
 

Bauexperte

2016-03-11 11:14:06
  • #5
You have already answered that yourself. The photovoltaics must thereby: correspond. That should only be answered by a specialist who can also be held liable for their statements. For you, it is additionally not _only_ the pure photovoltaics calculation; you already have fixed electricity consumers. For that, not much more is needed than an offer according to KfW 40 for the 3-family house, as well as the costs for moving the photovoltaic system and the calculation by an energy consultant. It is not rocket science for either; although the energy consultant will hardly proceed without upfront payment. Thus, their costs represent your risk in the matter. But honestly, I don’t understand – since you are at the source, where is your problem finding an energy consultant? No cooperations? You don’t have to spill the beans to answer; it’s none of my business and I don’t want to know either. I pay great attention to all components of house construction! I want references; not just to “cobble together” a house. And I want to be assured that home builders can enforce legitimate warranty claims. Overestimation is absolutely inappropriate here. Rhineland regards
 

Wastl

2016-03-11 11:43:34
  • #6
On the one hand, of course difficult, as not comparable, but: If someone sells you something they have no idea about, it is much more dangerous. It is better if people know the stone and can process it. There is rarely a black/white situation in the construction industry. Many roads lead to Rome. The stone must fit your requirements AND be processable for the construction company.
 

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