ᐅ Home Construction, KfW Efficiency House 55 Standard

Created on: 19 Oct 2014 09:10
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Xinette
Good morning,
We are planning to build a house for five people. Until now, we didn’t have to deal with this at all and have been living comfortably in our detached house that is already 40 years old.
Now, due to work reasons, we need to move again.
However, we have some time since we are currently still commuting (almost 3 hours every day).
The financing is basically secured, as we can sell our current house. The rest is mostly covered by the car costs we save.
We already have three offers: two for solid construction and one from a prefabricated house manufacturer.
The most cost-effective option so far is the following:

Increased thermal insulation of the base slab, highly insulating brick masonry, increased insulation of the facade, as well as insulation in the upper floor roof area as needed.

Efficient heat pump (Tecalor THZ 304/404 SOL including a three-year manufacturer warranty) with a 235-liter (62-gallon) hot water tank and preparation for cooling and connection of a solar system. Controlled ventilation with cross heat exchanger for up to 90% heat recovery, including pollen and fine dust filters. WEB module (Internet Service Gateway) with remote diagnostics and maintenance. Underfloor heating on the ground floor (except utility room) and upper floor, including room thermostats integrated into the switch program. Climate protection windows, triple-glazed (Ug 0.7-0.9), with mushroom-head locks and security fittings.

Built as a KfW 55 (energy-efficient) house. However, as I have read in construction blogs, this is done only with 17.5 cm (7-inch) Poroton bricks and exterior insulation with polystyrene.

Now comes my question: How should we approach this? Does it make sense to build it this way? The many posts confuse us completely.
Maybe you could at least point us in the right direction at first.
Best regards, Xinette
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Elina
19 Oct 2014 15:43
Here you can take a look for your place of residence:


Two color-coded maps of temperature distribution in Germany at 2 km and 3 km depth


It is also important that you don’t live directly above a confined aquifer, like in Wiesbaden, or above an anhydrite layer, like in Stauffen, otherwise it will lead to a disaster.
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toxicmolotof
19 Oct 2014 16:38
20,000 EUR more than gas? Who put that idea in your head?

Our ground source heat pump, including drilling, complete equipment, and installation, costs just 16,000 EUR. How do you expect to save that much with a gas boiler and gas connection?
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Legurit
19 Oct 2014 17:50
Guideline prices range from 35 to 70 € per meter of drilling. Depending on the number of boreholes and their depth, the costs can add up significantly. Additionally, the pump is considerably more expensive than a condensing boiler.
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toxicmolotof
19 Oct 2014 18:05
But again... drilling 100 meters (about 330 feet) costs roughly 5,000 euros, and even if you need 200 meters (about 660 feet), you’re looking at around 10,000 euros. That should comfortably cover heating for a single-family new build. A suitable heat pump including installation costs between 10,000 and 12,000 euros. In total, you’re at a maximum of about 22,000 euros, give or take a little.

If you factor in your 20,000 euro savings, a gas boiler with gas connection would have to be provided for free. But I doubt that.
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Legurit
19 Oct 2014 18:45
Well, yes – 20,000 euros might be a bit exaggerated.
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Bauexperte
19 Oct 2014 21:53
Good evening,
BeHaElJa schrieb:

Your pump has a COP of 2.82 at -7°C (19°F) – what does that mean? It produces 2.82 kWh of heat from 1 kWh of electricity. What does that imply?
I don’t think you really understand how an air-to-water heat pump system works; Tox has answered the rest very well.

Best regards, Bauexperte