9 ms·

Yes, absolutely - the house is a pretty big country side house from 1925, not uncommon in Germany. But (almost) impossible to insulate efficiently. My estimates

Yes, absolutely - the house is a pretty big country side house from 1925, not uncommon in Germany. But (almost) impossible to insulate efficiently. My estimates where €150k to €200k, just for the insulation, windows, and renewed heaters. In comparison, an 'oversized' 70 kWp PV only costs €100k, and also returns some income when not all of the power is used. The parameters widely differ between country and city: In the country, you usually have space (but lack money), in the city, you lack space but can often work with a pretty good income (= build a new, energy optimized house). Every house is different. If I build a new house today, of course this would look different.

bryanrasmussen 4y ago
yeah, there are so many old houses are still sitting around in Europe. My area almost every house was built in the late 1800s. Looks pretty nice, but insulation sucks.
switch007 4y ago
That estimate seems insane. Was that a “we’re too busy, go away” estimate? How big is the house?
- Helmut10001 4y ago
  It is quite a standard 2-generations house (at that 1925 time), 250 m² and two apartments, + a base level with an office. I am not saying that this is the universal standard - but it is _a_ standard that I do see quite often here, especially if you look outside cities, where the turnaround for reconstructon of houses is slower. .. and this was quite thoroughly calculated. I can tear down the house and build a new one, but apart from the waste of resources - building a new one will also cost minimum €200k - so I thought, why not 'oversize' PV, if it only costs €100k and can heat the house without improving on insulation? To emphasize, this conclusion will likely not apply to the majority of people (especially here on HN) because as many have said here, parameters and contexts differ widely.
  - swores 4y ago
    Does the calculation stay the same looking decades ahead? I'd have guessed that 200k to rip it down & build a new house that has great insulation - or even to just retrofit insulation and other upgrades to the existing building - would be expected to last longer before costing the same amount against to replace (and/or pricey maintenance/insurance of the more expensive PV, aircon etc.). And might therefore work out cheaper when looked at as a 50 year question rather than 1 year one? I don't presume to know more than you, not only don't I know about your specific situation I also know very little about these subjects generally, I'm just curious.
    - Helmut10001 4y ago
      Yes, it is difficult and I don't think it is possible to come up with a solution that fits all. What limited I can say: Insurance for the PV is cheaper than insurance for the insulation. That is because more problems with insulation can appear (e.g. fire damage, moisture) than with PV. Insulation of old houses is also far more complex than PV (someone pointed that our here). .. it was mentioned somewhere here, too: For some, the best solution will be to focus on reducing energy consumption; for other, the better option will be to focus on increasing local energy production. And a combination of both might be best for most.
      - deleted 4y ago
        [deleted]
otikik 4y ago
Wow that sounds too high. Maybe insulate only the parts you frequently use, perhaps?
- itengelhardt 4y ago
  As far as I know, around 1,000 Euro / sqm is a good estimate for bringing a 200+ kWh/(sqm * a) house down to about 85-100 kWh(sqm * a)
- Helmut10001 4y ago
  No offense - but insulation doesn't really work like this. If you insulate only one part, you will get massive problems with moisture through heat transfer. With insulation of old houses, so much can go wrong and then the only solution _is_ tearing down the house and building a new one.
  - illiac786 4y ago
    This is very interesting. I was told by some energy expert I could isolate 3 out of 4 outer walls and it would work fine. Do you have some documentation on the “moisture through heat transfer” issue?
    - Helmut10001 4y ago
      I do not have one at hand, but you should find this in almost any guide. It is not complicated: If you insulate 3 walls and leave one wall untouched - this wall will always be the coldest. That means the water contained in your air will condensate always at this wall (because it is the local minimum), resulting in mould and mildew on this wall over time. Now, there are all kinds of solutions and they all have caveats. As someone said here, old houses are build so that walls are semi-permeble, meaning that heat constantly wanders to the outside. That also means that the dew point is pretty far towards the outside in winter - water can get out of the house. If you insulate the inner wall, the dew point will move more towards the inside, meaning your walls will get wet and water will take longer to move outside. If you insulate the outside, water cannot get out at all - you must find another solution to get the moisture out of the house. It gets more complicated the more you dive into this topic.
z9znz 4y ago
I live in a house in a village in the Netherlands. The house is from 20-150 years old, depending on which section you're in. It is cold as f in this place all winter. It's also hot as f in these new 37 degree summers. So the question is, is the problem the old homes, or our insistence to live in inefficient buildings in places with poor climates? Of course in this country, there's more demand for housing than can be met, so living someplace modern (efficient/comfortable) is not necessarily an option based on price. So the next choice is relocating to a different country which has a more livable climate. I love architectural history, but we would all be better off if modern engineering and design decisions were made on new structures to replace the grossly inefficient current ones.
- danielscrubs 4y ago
  Currently living in a rich area, 20 stories very modern high apartment complex. The first thing I thought when stepping into the apartment for the first time with its massive windows was “jikes the windows are leaking heat like crazy”. In my old home that was 60 years old it had way better insulation (with triple layered windows). What I’m trying to say is that this is about incentives, not about how old things are. The modern building let their tenants cover the AC cost while the old one had water heating instead included.
  - z9znz 4y ago
    Not sure what part of the world you're in, but OP was describing Germany, and I'm in Netherlands. Both of these countries have pretty strict requirements for energy efficiency of new buildings. So at least here, it would be safe to assume that a < 10 year old home or apartment would be much more efficient (and comfortable) than a 30+ year old one. Also, there's a new government initiative to provide incentives and special financing for property owners (who rent their property) to bring the efficiency of all properties up to a decent minimum level by 2030 if they wish to be allowed to continue renting them out. I imagine there may be some exclusions for certain very old properties, especially historical/monumental ones. But regardless, it should have a big positive impact.
  - ClumsyPilot 4y ago
tarsinge 4y ago
From what I've seen with old country side houses in France just insulating the roof and the windows can already bring very good results (heat lost through walls is usually only around 25% of all the losses). A quick and cheap solution for the roof is to lose the attic and blow the isolating material directly on it.

bryanrasmussen 4y ago

yeah, there are so many old houses are still sitting around in Europe. My area almost every house was built in the late 1800s. Looks pretty nice, but insulation sucks.

switch007 4y ago

That estimate seems insane. Was that a “we’re too busy, go away” estimate? How big is the house?

Helmut10001 4y ago
It is quite a standard 2-generations house (at that 1925 time), 250 m² and two apartments, + a base level with an office. I am not saying that this is the universal standard - but it is _a_ standard that I do see quite often here, especially if you look outside cities, where the turnaround for reconstructon of houses is slower. .. and this was quite thoroughly calculated. I can tear down the house and build a new one, but apart from the waste of resources - building a new one will also cost minimum €200k - so I thought, why not 'oversize' PV, if it only costs €100k and can heat the house without improving on insulation? To emphasize, this conclusion will likely not apply to the majority of people (especially here on HN) because as many have said here, parameters and contexts differ widely.
- swores 4y ago
  Does the calculation stay the same looking decades ahead? I'd have guessed that 200k to rip it down & build a new house that has great insulation - or even to just retrofit insulation and other upgrades to the existing building - would be expected to last longer before costing the same amount against to replace (and/or pricey maintenance/insurance of the more expensive PV, aircon etc.). And might therefore work out cheaper when looked at as a 50 year question rather than 1 year one? I don't presume to know more than you, not only don't I know about your specific situation I also know very little about these subjects generally, I'm just curious.
  - Helmut10001 4y ago
    Yes, it is difficult and I don't think it is possible to come up with a solution that fits all. What limited I can say: Insurance for the PV is cheaper than insurance for the insulation. That is because more problems with insulation can appear (e.g. fire damage, moisture) than with PV. Insulation of old houses is also far more complex than PV (someone pointed that our here). .. it was mentioned somewhere here, too: For some, the best solution will be to focus on reducing energy consumption; for other, the better option will be to focus on increasing local energy production. And a combination of both might be best for most.
    - deleted 4y ago
      [deleted]

otikik 4y ago

Wow that sounds too high. Maybe insulate only the parts you frequently use, perhaps?

itengelhardt 4y ago
As far as I know, around 1,000 Euro / sqm is a good estimate for bringing a 200+ kWh/(sqm * a) house down to about 85-100 kWh(sqm * a)
Helmut10001 4y ago
No offense - but insulation doesn't really work like this. If you insulate only one part, you will get massive problems with moisture through heat transfer. With insulation of old houses, so much can go wrong and then the only solution _is_ tearing down the house and building a new one.
- illiac786 4y ago
  This is very interesting. I was told by some energy expert I could isolate 3 out of 4 outer walls and it would work fine. Do you have some documentation on the “moisture through heat transfer” issue?
  - Helmut10001 4y ago
    I do not have one at hand, but you should find this in almost any guide. It is not complicated: If you insulate 3 walls and leave one wall untouched - this wall will always be the coldest. That means the water contained in your air will condensate always at this wall (because it is the local minimum), resulting in mould and mildew on this wall over time. Now, there are all kinds of solutions and they all have caveats. As someone said here, old houses are build so that walls are semi-permeble, meaning that heat constantly wanders to the outside. That also means that the dew point is pretty far towards the outside in winter - water can get out of the house. If you insulate the inner wall, the dew point will move more towards the inside, meaning your walls will get wet and water will take longer to move outside. If you insulate the outside, water cannot get out at all - you must find another solution to get the moisture out of the house. It gets more complicated the more you dive into this topic.

z9znz 4y ago

I live in a house in a village in the Netherlands. The house is from 20-150 years old, depending on which section you're in. It is cold as f in this place all winter. It's also hot as f in these new 37 degree summers. So the question is, is the problem the old homes, or our insistence to live in inefficient buildings in places with poor climates? Of course in this country, there's more demand for housing than can be met, so living someplace modern (efficient/comfortable) is not necessarily an option based on price. So the next choice is relocating to a different country which has a more livable climate. I love architectural history, but we would all be better off if modern engineering and design decisions were made on new structures to replace the grossly inefficient current ones.

danielscrubs 4y ago
Currently living in a rich area, 20 stories very modern high apartment complex. The first thing I thought when stepping into the apartment for the first time with its massive windows was “jikes the windows are leaking heat like crazy”. In my old home that was 60 years old it had way better insulation (with triple layered windows). What I’m trying to say is that this is about incentives, not about how old things are. The modern building let their tenants cover the AC cost while the old one had water heating instead included.
- z9znz 4y ago
  Not sure what part of the world you're in, but OP was describing Germany, and I'm in Netherlands. Both of these countries have pretty strict requirements for energy efficiency of new buildings. So at least here, it would be safe to assume that a < 10 year old home or apartment would be much more efficient (and comfortable) than a 30+ year old one. Also, there's a new government initiative to provide incentives and special financing for property owners (who rent their property) to bring the efficiency of all properties up to a decent minimum level by 2030 if they wish to be allowed to continue renting them out. I imagine there may be some exclusions for certain very old properties, especially historical/monumental ones. But regardless, it should have a big positive impact.
- ClumsyPilot 4y ago

tarsinge 4y ago

From what I've seen with old country side houses in France just insulating the roof and the windows can already bring very good results (heat lost through walls is usually only around 25% of all the losses). A quick and cheap solution for the roof is to lose the attic and blow the isolating material directly on it.