DaSch17
2020-07-23 11:27:21
- #1
Thank you all for the high-quality discussion. It definitely helped me make significant progress!
I have understood that so far. The idea was to rely on an electric underfloor heating instead of temporary supplementary heating via electric towel dryer or infrared heating. Thanks to you, I now understand that this is both energetically and economically nonsense!
Since we are building KfW 40 Plus, we are logically planning with 7.5 kWP photovoltaic + 7.5 kWh battery storage so that in the optimal case, the general electricity demand can be fully covered and the heat (pump) electricity demand partially covered by self-produced electricity:
Own consumption approx. 4,000 kWh (1,800 kWh direct consumption + 2,200 kWh from battery storage)
Total electricity consumption approx. 6,500 kWh (3,500 kWh general electricity + 3,000 kWh heat pump) minus 4,000 kWh from own consumption = 2,500 kWh at heat pump electricity tariff = 525.15 EUR p.a. or 43.76 EUR p.m. according to online comparison portal.
Too nicely calculated?
After our discussion here, my feeling says it now makes most sense to continue planning with an air-to-water heat pump + underfloor heating and to control supplementary heating in the parents’ and children’s bathrooms, for example, via infrared mirror heaters.
To everything already mentioned, add that every degree more in room temperature during winter directly affects the wallet. However, manufacturers only provide consumption values for the generally "usual" 19, 21, 22°. Sorry, but that is not warm enough for everyone in winter. The supposed "saving" by shutting off rooms and not heating them has the opposite effect, because it only increases the heating demand of the surrounding rooms, which then have to heat the unheated areas as well (since it is a heated envelope). For example, an electric underfloor heating in bathrooms (in a non-passive house) is a crazy idea if there is no additional usual underfloor heating providing base warmth underneath.
Hot water has already been mentioned. Every liter counts here as well. It is best to install as much heat recovery as possible here too.
No question, heat pumps are a great technology. If the house, location, and user behavior fit.
Yes and no, because you still have to bring the same amount of heat into the room and have the same supply temperatures as with a normal underfloor heating.
Since an electric underfloor heating usually has little or no screed coverage, the distance the heat travels back is shorter and it heats up only a small amount of storage (screed).
As a result, a room cools down faster when it is off, and the heat is transferred to the room more quickly when it is on.
I can’t assess how much faster it is, but in my opinion it won’t be that much due to the low supply temperatures.
I have understood that so far. The idea was to rely on an electric underfloor heating instead of temporary supplementary heating via electric towel dryer or infrared heating. Thanks to you, I now understand that this is both energetically and economically nonsense!
Since we are building KfW 40 Plus, we are logically planning with 7.5 kWP photovoltaic + 7.5 kWh battery storage so that in the optimal case, the general electricity demand can be fully covered and the heat (pump) electricity demand partially covered by self-produced electricity:
Own consumption approx. 4,000 kWh (1,800 kWh direct consumption + 2,200 kWh from battery storage)
Total electricity consumption approx. 6,500 kWh (3,500 kWh general electricity + 3,000 kWh heat pump) minus 4,000 kWh from own consumption = 2,500 kWh at heat pump electricity tariff = 525.15 EUR p.a. or 43.76 EUR p.m. according to online comparison portal.
Too nicely calculated?
After our discussion here, my feeling says it now makes most sense to continue planning with an air-to-water heat pump + underfloor heating and to control supplementary heating in the parents’ and children’s bathrooms, for example, via infrared mirror heaters.