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> A properly insulated house in any temperate climate require very little heating or cooling. A "properly insulated" house still requires something around 0,5

> A properly insulated house in any temperate climate require very little heating or cooling. A "properly insulated" house still requires something around 0,5 W/m2/K. Modeling a moderate 120 m2 house in the coldest months when the temperatures hit 15-20 negative you still need 2,5 kW of heat with domestic hot water on top. Put in the efficiency of a heat pump and you are still easily looking at half a mega watt-hour per month. ~1MWh for a whole house is very reasonable number during winter months, sans electric mobility. That's entirely unrealistic to cover with batteries with current battery technologies alone, electricity generation is absolutely REQUIRED. Windmills can help soften the blow and storage needs substantially, but the TFA is about solar, which is effectively absent during the winter.

toasty228 7mo ago
> 0,5 W/m2/K. That was a good number in 1980 lmao (or in the US maybe), passive houses are often 1/5th of that. I'm talking 25cm+ of rockwool in the walls, 40cm on the roof and triple pane windows, mostly facing south, reasonably shaped house that conserve heat by design, etc. 0.5 W/m²/K is a good value.... for a window, certainly not for the overall house, for a wall it wouldn't even pass code in most of Europe > That's entirely unrealistic to cover with batteries with current battery technologies alone It already is a reality for many people.
- friendzis 7mo ago
  > passive houses are often 1/5th of that. > 0.5 W/m²/K is a good value.... <...> for a wall it wouldn't even pass code in most of Europe There's a mix of miscommunication and wat. I'm using approximate floor area values here, not perimeter walls. 0.1 W/m2/K for a WALL is definitely not a "passive" house, that's barely A++. > I'm talking 25cm+ of rockwool in the walls, 40cm on the roof and triple pane windows, Yep, this gets you something like 0.5 realistic, maaaaybe up to 0.3 in the models.
- friendzis 7mo ago
  > > > That's entirely unrealistic to cover with batteries with current battery technologies alone > It already is a reality for many people. Megawatt-hour level home-battery installs? Show us a picture. That's literally a room full of batteries. The actual reality is having ten or so kilowatt-hours to balance rooftop solar.

toasty228 7mo ago

> 0,5 W/m2/K. That was a good number in 1980 lmao (or in the US maybe), passive houses are often 1/5th of that. I'm talking 25cm+ of rockwool in the walls, 40cm on the roof and triple pane windows, mostly facing south, reasonably shaped house that conserve heat by design, etc. 0.5 W/m²/K is a good value.... for a window, certainly not for the overall house, for a wall it wouldn't even pass code in most of Europe > That's entirely unrealistic to cover with batteries with current battery technologies alone It already is a reality for many people.

friendzis 7mo ago
> passive houses are often 1/5th of that. > 0.5 W/m²/K is a good value.... <...> for a wall it wouldn't even pass code in most of Europe There's a mix of miscommunication and wat. I'm using approximate floor area values here, not perimeter walls. 0.1 W/m2/K for a WALL is definitely not a "passive" house, that's barely A++. > I'm talking 25cm+ of rockwool in the walls, 40cm on the roof and triple pane windows, Yep, this gets you something like 0.5 realistic, maaaaybe up to 0.3 in the models.
friendzis 7mo ago
> > > That's entirely unrealistic to cover with batteries with current battery technologies alone > It already is a reality for many people. Megawatt-hour level home-battery installs? Show us a picture. That's literally a room full of batteries. The actual reality is having ten or so kilowatt-hours to balance rooftop solar.