New Single-Family House: KFW 40 Plus - IR Heating or Heat Pump?

  • Erstellt am 2016-10-19 13:47:19

steffjay2k

2016-10-19 13:47:19
  • #1
Hello everyone.

After several weeks of research and consultation, I have come to the conclusion that I should probably get some more experience and opinions directly from those who have already built houses. I will try to describe my building project (starting from 2017) as detailed as possible, so hopefully you can help me a bit. Specifically, it is about the question of which heating system I want to install:

Planned is a single-family house built with solid wood construction (via KLH - cross laminated timber). And as of today, we will also reach the Kfw40 Plus standard regarding insulation. The energy certificate is in progress and will be provided later. The location of the plot is in 89**** near Neu-Ulm in Bavaria. Here first are the floor plans:

It has 195m² floor space + the garage, which of course is not supposed to be heated. The utility room is also already marked, there is no basement.

[ATTACH alt="neubau-efh-kfw-40-plus-ir-heizung-oder-Wärmepumpe-159242-2.jpg"]12164[/ATTACH] [ATTACH alt="neubau-efh-kfw-40-plus-ir-heizung-oder-Wärmepumpe-159242-4.jpg"]12166[/ATTACH]

Now to the already known details regarding the heating and building technology. So far we only have offers for an infrared heating system, which I have strongly favored up to now. But unfortunately, even after more than 2 months of research, I have to realize that it is not very often recommended in various forum posts, etc. So I can only compile my current facts and hope for some suggestions for improvement. And of course corresponding tips in comparison to a heat pump:

- Decentralized ventilation system from Vaillant (approx. 4000€)
- Domestic hot water heat pump from Waterkotte (approx. 3500€)

- LG Neon bifacial photovoltaic modules with 10 kWp (approx. 21,000€)
- Senec storage 12 kWh + accessories (approx. 18,000€)
- IR heating elements from Digel-Heat (approx. 8,000€)

The ventilation system and the domestic hot water heat pump are more or less mandatory if I want the Kfw 40 Plus house. With the IR heating topic it becomes immediately clear that the heaters themselves make up the smallest cost factor; rather, the photovoltaic system and the storage are expensive. But I would have no problem with that at all – after all, I then produce the electricity I need myself. Of course, the problem here is: in the evening and in winter no electricity is produced when you need it most... but that is a fundamental discussion which I do NOT want to make the topic here.

Rather, I created an Excel table for myself, in which the individual IR panels are listed. I inserted rough usage figures (hours per day), wrote down the (fictional) heating period and calculated with a price of 29 cents per kWh. The heating period indicates that a panel, for example, will only draw power 50% of the time – i.e. 30 minutes per hour. [ATTACH alt="neubau-efh-kfw-40-plus-ir-heizung-oder-Wärmepumpe-159242-6.jpg"]12168[/ATTACH]

Long story short: I come to an average heating cost of 287€ per month – depending on the heating period considerably less as well. And not yet calculated is the self-produced electricity (photovoltaic system) and possibly the offset by feed-in remuneration from surplus electricity produced. This should only be included to a limited extent here because I want to compare the actual costs without subsidies. And that with a heat pump.

Hopefully this is where many clever minds from the forum will come into play: I have so far almost no experience with heat pumps. But can you a) understand the above calculation or have gross mistakes slipped in? and b) Can one roughly estimate the cost of a heat pump for the above building project? Regarding investment & running costs.

Who has experience with Senec storage?
A somewhat longer text but I hope you can help.
 

Legurit

2016-10-19 13:58:09
  • #2
Your photovoltaic system is expensive. Over 2,000 € per kWp. IR is exciting but as you have recognized, after a week of snow extremely expensive - probably even earlier - 12 kWh of heat are definitely wasted... Roughly: heat pump including hot water 20 - 25 T €. Monthly costs max 50 €.
 

Alex85

2016-10-19 15:15:06
  • #3
Photovoltaics are quite expensive. The storage capacity does not match the photovoltaics and is even more uneconomical with electric heating/heat pumps than it already is.

What is your motivation behind the 40,000€ for additional, non-profitable technology?

The difference between KfW 40 and 40 Plus is the technology package. The primary energy factor and the transmission heat loss are the same. So buying photovoltaics, buying storage, and getting 5,000€ more funding ... that can't be the reason why someone would consider that.

I find IR heating interesting and haven't read much about it yet. My first question is about the efficiency. Your outlined consumption costs are of course severe.
 

Legurit

2016-10-19 16:26:36
  • #4
Efficiency is 1 = 1 kWh of electricity becomes 1 kWh of heat.
 

steffjay2k

2016-10-20 13:30:16
  • #5
Thank you for the honest feedback. I perhaps should have added that all previous considerations aim at the KWF funding: 2 units of €15,000 subsidy each and then the 10,000-houses program from Bavaria. However, this requires a 12 kWh storage, which is why everything seems "a bit" oversized.

The energy certificates are currently being prepared and will of course (!) be included in the comparison... but as I wrote at the beginning, I just wanted to gather some opinions on what other builders decide for.
 

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