ᐅ KfW40 House Project 2020 *Planning Concepts*

Hello everyone,

I’d like to briefly introduce our house project here. The goal is to exchange ideas with you on various topics and possibly create specific threads for detailed subtopics. Since we haven’t signed any contract yet and only have two initial rough quotes, I can’t provide details like heating load calculations at this stage. Thanks for your understanding.

Now for the first rough plan:
- Single-family house with about 170-180m² (1830-1940 sq ft) living space
- Bungalow
- Only the ground floor will be occupied
- Geothermal heating with 2 boreholes, each 80m (260 ft) deep, and a Nibe S1255 unit
- Floor slab insulation with glass gravel
- 36.5cm (14 inches) exterior walls made of Ytong masonry units
- Ceiling insulation using Ytong ceiling elements (maybe too expensive!?)
- Household of 2 people (likely to increase to 4)
- Decentralized ventilation (I’m not very satisfied with ReglerAir window units)
- Photovoltaic system on the roof, 7-10 kWp, without battery storage
- Triple-glazed PVC windows

I would appreciate your initial assessment and feedback.

Budget: Moderate, two incomes; total costs for the complete house (excluding furniture and kitchen) should not exceed 400,000 euros.

I will provide more information later.

Best regards and thanks for your feedback!
Peter

PeterS90 schrieb:

36.5cm (14.4 inches) exterior walls of

It will be quite challenging to achieve KfW 40 standard with the masonry.
A total budget of 400k all-inclusive might also be tight for a KfW 40 solid construction, depending on the region.

If you want to stick with monolithic masonry, it’s better to aim for KfW 55, as there is now a good subsidy available. For KfW 40, I would recommend timber frame or a prefabricated house, or if necessary, solid construction with external thermal insulation composite system (ETICS).

I had considered KfW40 because of the new subsidies but already suspected that it might not be enough to meet my expectations. However, the additional cost for thicker masonry will probably offset the subsidy in the end. The building location is a rural area in Brandenburg.

KfW55 is already quite good, especially with the new subsidies. I would only improve on it if it can be done without much additional cost.

A central mechanical ventilation system with heat recovery is preferable.

Stay flexible during the early planning phase. I doubt you are strongly committed to Ytong blocks, so I wouldn’t fixate on the wall and general construction too early. Instead, make it dependent on the supplier. You can then ask detailed questions and request adjustments if something doesn't suit you.

PeterS90 schrieb:

The construction area is a rural region in Brandenburg.

In that case, you might even have a chance to stay close to your budget by doing some work yourself. Provided you leave out extravagant things like KfW40 standard with a solid wall and overly expensive fittings.