14 ms·

With all due respect, looking at your numbers my hunch is that you need better insulation. I know a person who has about 10kWp installed on a passivhaus here i

With all due respect, looking at your numbers my hunch is that you need better insulation. I know a person who has about 10kWp installed on a passivhaus here in latitude 59N and says that having a heat pump is overkill for them.

Helmut10001 4y ago
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.
dmitriid 4y ago
> With all due respect, looking at your numbers my hunch is that you need better insulation. With all due respect these are the kinds of "tiny" details that renewable enthusiasts conveniently forget. Yes, this person's house needs better insulation. As does everybody else's. You can't just wave this away with "your math is wrong". These numbers reflect reality, not wishful thinking.
- dvh 4y ago
  In a worst case scenario (no gas, no grid electricity), he could heat only one room instead of entire house.
- stewbrew 4y ago
  How is this a tiny detail. We live in a passivhaus. We hardly ever heat. Improving insulation of old houses is an important aspect here. Reducing energy consumption is as important as generating and storing energy.
  - JohnHaugeland 4y ago
    - stewbrew 4y ago
      I don't see how this relates to this discussion other than by spamming this subthread.
      - JohnHaugeland 4y ago
        I appreciate that you don't see how a direct answer to your question, where you asked what you don't understand and it was spelled out for you, doesn't relate to the discussion. I agree, your attempt to make the world's energy problems about the way you live personally in a Passivhaus doesn't relate to this discussion. That was kind of my point, as well as the point of several other people who've replied to you so far. You might as well ask why everyone doesn't just live in an igloo. It's because they don't work in the places that most people live, like downtown. And if you try to ask the company "hey, I see that you claim you reduce carbon by 90%, why wouldn't LEED certify you, they only require 30%," the company will quickly change the topic. I'll try it a little differently. "If your solution doesn't work for 99.99% of humans, your solution just doesn't work." No, I wasn't selling anything. This wasn't spam. But, you knew that. I was making a good faith attempt to answer the question you asked.
ekianjo 4y ago
> better insulation better insulation is not cheap and therefore not everyone can afford to do it. Also the same people who want renewables are usually opposed to building new housing so there's that.
- taneq 4y ago
  It's not super expensive, really. And this is something that building codes can address - either via the gentle option of requiring all newly built dwellings to be thermally efficient, or the somewhat more assertive route of requiring any home sold to have adequate insulation.
- brtkdotse 4y ago
  The actual insulation is stupid cheap when you look at the ROI. However, installing in on an existing house is really tricky and you can cause a lot of moisture related damage if you do it in the wrong way.
  - Roritharr 4y ago
    The house I live in, like everyone's in my street, is from the late 1800s. Insulating those houses from the outside is very expensive, to the tune of 200k, where the house is worth around 500k in the inflated environment we're in. At the very same time, I haven't found a single insurance company willing to insure the house after insulation for insulation related moisture damage. This makes insulating this house an absurdly bad financial decision, since once you have moisture damage in any part of this material, you can basically demolish most of the walls since it soaks like a sponge. Mind you, I have not started going into the pitfalls of the legality of even touching a house this old in Germany, where you have to deal with "Denkmalschutz". Insulating new construction and retrofitting insulation are two absolutely different things and barely have anything to do with each other from the cost-benefit ratio.
    - brtkdotse 4y ago
      Absolutely, and the thing about old houses is that they've evolved to keep moisture and ventilation in check without access to modern tech. Modern tech, as you point out, usually makes things worse. My house in Sweden is from the 1950's and I still had to be _very_ mindful when adding insulation. The best thing I've found is cellulose-based insulation, basically shredded newspapers lined with salts and pressed to sheets. The can buffer a lot of moisture without developing mold.

Helmut10001 4y ago

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.

dmitriid 4y ago

> With all due respect, looking at your numbers my hunch is that you need better insulation. With all due respect these are the kinds of "tiny" details that renewable enthusiasts conveniently forget. Yes, this person's house needs better insulation. As does everybody else's. You can't just wave this away with "your math is wrong". These numbers reflect reality, not wishful thinking.

dvh 4y ago
In a worst case scenario (no gas, no grid electricity), he could heat only one room instead of entire house.
stewbrew 4y ago
How is this a tiny detail. We live in a passivhaus. We hardly ever heat. Improving insulation of old houses is an important aspect here. Reducing energy consumption is as important as generating and storing energy.
- JohnHaugeland 4y ago
  - stewbrew 4y ago
    I don't see how this relates to this discussion other than by spamming this subthread.
    - JohnHaugeland 4y ago
      I appreciate that you don't see how a direct answer to your question, where you asked what you don't understand and it was spelled out for you, doesn't relate to the discussion. I agree, your attempt to make the world's energy problems about the way you live personally in a Passivhaus doesn't relate to this discussion. That was kind of my point, as well as the point of several other people who've replied to you so far. You might as well ask why everyone doesn't just live in an igloo. It's because they don't work in the places that most people live, like downtown. And if you try to ask the company "hey, I see that you claim you reduce carbon by 90%, why wouldn't LEED certify you, they only require 30%," the company will quickly change the topic. I'll try it a little differently. "If your solution doesn't work for 99.99% of humans, your solution just doesn't work." No, I wasn't selling anything. This wasn't spam. But, you knew that. I was making a good faith attempt to answer the question you asked.

ekianjo 4y ago

> better insulation better insulation is not cheap and therefore not everyone can afford to do it. Also the same people who want renewables are usually opposed to building new housing so there's that.

taneq 4y ago
It's not super expensive, really. And this is something that building codes can address - either via the gentle option of requiring all newly built dwellings to be thermally efficient, or the somewhat more assertive route of requiring any home sold to have adequate insulation.
brtkdotse 4y ago
The actual insulation is stupid cheap when you look at the ROI. However, installing in on an existing house is really tricky and you can cause a lot of moisture related damage if you do it in the wrong way.
- Roritharr 4y ago
  The house I live in, like everyone's in my street, is from the late 1800s. Insulating those houses from the outside is very expensive, to the tune of 200k, where the house is worth around 500k in the inflated environment we're in. At the very same time, I haven't found a single insurance company willing to insure the house after insulation for insulation related moisture damage. This makes insulating this house an absurdly bad financial decision, since once you have moisture damage in any part of this material, you can basically demolish most of the walls since it soaks like a sponge. Mind you, I have not started going into the pitfalls of the legality of even touching a house this old in Germany, where you have to deal with "Denkmalschutz". Insulating new construction and retrofitting insulation are two absolutely different things and barely have anything to do with each other from the cost-benefit ratio.
  - brtkdotse 4y ago
    Absolutely, and the thing about old houses is that they've evolved to keep moisture and ventilation in check without access to modern tech. Modern tech, as you point out, usually makes things worse. My house in Sweden is from the 1950's and I still had to be _very_ mindful when adding insulation. The best thing I've found is cellulose-based insulation, basically shredded newspapers lined with salts and pressed to sheets. The can buffer a lot of moisture without developing mold.