13 ms·

It is interesting that you insulate under the house. One of the more intriguing passive house designs I saw was one where the insulation went down 2-3m into th

by kitd 5y ago

It is interesting that you insulate under the house. One of the more intriguing passive house designs I saw was one where the insulation went down 2-3m into the ground all around the house footprint. This trapped the natural ground heat within that area and fed it upwards into the house. It took about 18 months for the ground to warm up, but once it was there, the ground/house warmed itself with virtually no input. This was in the UK. Colder climates may vary ofc.

Gravityloss 5y ago
How would that work? Average temperature in the UK is about 15 C. If your house is at 24 C, this would mean you are constantly leaking heat into the ground from the bottom... I guess one can consider the cube of earth an insulator, it's got a lousy insulation value per meter but it makes it up in thickness.
- arethuza 5y ago
  Don't think 15C is correct - looks more like 8.5C to 11C in England and 7C to 9C in Scotland. http://projectbritain.com/weather/average.htm http://projectbritain.com/weather/average.htm
  - a_square_peg 5y ago
    You can look up ground temperature for your location here - https://weatherdownloader.oikolab.com/downloader https://weatherdownloader.oikolab.com/downloader. Layer 4 is between 1m to 3m depth beneath the surface.
    - arethuza 5y ago
      Apologies, I didn't appreciate you meant average temperature underground - that is definitely much warmer. We have a ventilation shaft for an old limestone mine near our house and on a cold day the warm air rising from it is very noticeable.
      - a_square_peg 5y ago
        I wasn't the commenter so no worries about apologies... just wanted to point out where you can find this information. :)
  - Gravityloss 5y ago
    Sorry, I was wrong indeed, thanks for the correction
whirlwin 5y ago
We have an old house from 1988 located in Norway. Walking on the non-insulated wooden floor is very unpleasant. We will refurbish, and insulate under the floor, but it will not be anything near a passive house because of other construction shortcomings
- deleted 5y ago
  [deleted]
- ricardobayes 5y ago
  well try non-insulated tiles here in Spain haha. I don't know why houses are built to such a low standard in Spain. Even the UK had better quality constructions when I was there, and that says a lot (single glazed windows, poor insulation, weak plumbing)
  - joking 5y ago
    no harsh climate overall so much less insulation is needed?
    - ricardobayes 5y ago
      Mainland Spain falls into the single digits at night at winter so definitely would need insulation, because there is also no central heating. People resort to heating with their aircons and portable heaters. I'm sad because I expected better infrastructure from 45% income tax at the highest bracket.
      - jakub_g 5y ago
        I come from Poland (sub-zero in winter; can be anywhere from -20C to +10C but typically 0-5C), but the winter I lived on the Spanish eastern coast was the coldest in my life: thin walls and windows, stone floor, no heating apart from little portable heaters, 5 degrees and rain outside. Now I live in French southern coast, the buildings are slightly better but still poor. In my place even with all heaters I have on max, I'm nowhere near as comfortable as in properly built and heated apartments in my home place (actually when visiting friends in Poland in winter I'm almost overheating!). Basically half of the year it's quite uncomfortable to stay at home for prolonged time: for ~4 months a year at winter; then again for ~2-3 months at summer (+26C at home with blinds down unless you put aircon on max for hours). Kinda suboptimal for WFH to be honest :)
leobg 5y ago
Exactly. Talking about thermal mass! There’s also the movement of underground houses. They use the ground for cooling in summer and for insulation in winter. Also it apparently makes for great noise reduction, in spite of having lots of windows, light and views. See the book “Recovering America: A More Gentle Way to Build”.
- swader999 5y ago
  Underground houses can be a nightmare dealing with water infiltration, codes and the power of soil.
poseva 5y ago
Really interesting. I've read about also "foundation insulation skirt" that allows you to create a warmer earth mass under the house. To be honest this was the biggest "complaint" that others had in regards of how a built the house, the general knowledge says that the earth is warm and you don't need to insulate against it... but the earth is maybe 5-10 degree, of course warmer than outside -5..-10 but still a lot colder than what we want inside the house, 20,21 degree C.
- jaclaz 5y ago
  That depends on how deep you dig, but of course going deep enough has a cost that may be far greater than the kind of insulation you used. The 20-25% of increase in cost is a good proxi (from my personal experience I would have said 25-30%), but, from an economical standpoint it should be compared with savings over time (in the same region). To give you an example in Italy, last time I calculated it, this 25-30% increase of costs corresponds - loosely - to the costs of heating for 20 years or so (bar the crazy increases in prices of energy that just happened), so it becomes more a "philosophical" choice than anything else to go for passive or almost passive.
  - Sankozi 5y ago
    5% return per year (or more in case of price changes or regulations forcing you to change heating source) does not seem that "philosophical".
    - jaclaz 5y ago
      I don't understand fully your way of reasoning. A normal house costs - say - 200,000 "units" (dollars, euro, whatever). Making it "energy saving" costs an additional 60,000 units. In 20 years time you will be spending 60,000 units (3,000 per year) less for energy costs (and here we are assuming that ventilation and heating/cooling machines in the "better" house have the same maintenance costs than the ones in "normal" house, whilst usually, since they are more complex systems they tend to be more expensive). You essentially have a "break even" point 20 years in the future, from there onwards you start saving money. First thing, you need, now, 260,000 units instead of 200,000 (and not all people may be able to afford this). Then, if, for whatever reasons, you don't use the house at all times in these 20 years, or you need to sell it before that time you are unlikely to fully get the savings. Additionally, in less than 20 years time it is possible that someone comes out with a mega-para-hyper-ultra climatization device that makes yearly energy costs go down by (say) 90%. So, if you want to do the "right thing" from a climate/energy savings point of view, by any means choose to invest in a passive house, but it remains essentially a "philosophical" decision, not an economical one.
mrweasel 5y ago
> It is interesting that you insulate under the house. Isn't that pretty normal, I mean maybe not three meters down, but modern foundations are required to be isolated in many places. The legal requirement in Denmark is at least 300mm of isolation under the house.
- 8fingerlouie 5y ago
  And that's not a new thing either. In my 1970's house we have 150mm insulation under the house from the original build, 150mm in the walls and 200mm on the roof. We added another part to the house a few years ago, and that was 300mm insulation in floor/walls/roof. Since the walls are made of brick with a depth of 7cm, it means the walls are 7+7+30= 44cm thick (plus some "slack") Even my 1980's summerhouse has 100mm insulation in floor/walls/roof.
- jmrm 5y ago
  That depends of the the place where you live. In middle to the south of Spain, the floor of houses are normally made of marble (or other ceramic material) slabs on top of a little layer of some glue cement, on top of the armoured concrete slab foundation, but on the north is a lot common to have wooden floors with air chamber of a similar size.
- kitd 5y ago
  It is indeed normal. I mentioned it by way of an intro to the unusual alternative I saw.
markvdb 5y ago
> It is interesting that you insulate under the house. Near our place in the countryside, required foundation depth is 1.4m to protect from frost heave. Use an insulated slab and that requirement goes away. The insulation keeps the heat in the ground. It protects the ground under the house from freezing. Nobody cares about regulations here, but they do about getting proper foundations...
- lelanthran 5y ago
  > The insulation keeps the heat in the ground. It protects the ground under the house from freezing. If it is preventing the ground under the house from freezing, then it is supplying heat to that ground. That's a energy-negative process - some of the heat you generate is used to maintain the warmth of the ground.
  - jounker 5y ago
    Some of your heat is always going into the ground. The insulation prevents it from dissipating into the environment.
  - markvdb 5y ago
    Au contraire, my dear Watson. Without under-slab insulation, the heat emanating from the ground below the house escapes very quickly. This heat we don't generate. It occurs naturally. This is about using the naturally escaping heat to keep the ground under the house from freezing, about raising the frost depth. This technique is especially interesting for holiday homes not permanently heated in northern climates. It's fairly standard in Scandinavia, up and coming in the Baltics, but less known in the US. In the US, it's usually called FPFS or frost protected shallow foundations. [0] [0] https://www.ncei.noaa.gov/products/land-based-station/frost-protected-shallow-foundations https://www.ncei.noaa.gov/products/land-based-station/frost-...
aaron695 5y ago
throw0101a 5y ago
> It is interesting that you insulate under the house. This is part of the building code in many areas: do a search for [under] "slab insulation". * https://www.buildingscience.com/documents/information-sheets/basement-insulation https://www.buildingscience.com/documents/information-sheets... * https://www.finehomebuilding.com/project-guides/insulation/insulating-a-slab-on-grade https://www.finehomebuilding.com/project-guides/insulation/i... It should be at least R-10 (RSI 1.8): * https://www.youtube.com/watch?v=O2dNp9bicSk https://www.youtube.com/watch?v=O2dNp9bicSk * https://www.youtube.com/watch?v=XKp0wRzvR-g https://www.youtube.com/watch?v=XKp0wRzvR-g
alksjdalkj 5y ago
> It is interesting that you insulate under the house. I think anyone who's gone camping will appreciate the need for insulation between the ground and whatever you're trying to keep warm - a good sleeping pad is crucial for keeping warm.
voisin 5y ago
Do you have a link on this? I’d love to read more about this.

by kitd 5y ago

Gravityloss 5y ago

How would that work? Average temperature in the UK is about 15 C. If your house is at 24 C, this would mean you are constantly leaking heat into the ground from the bottom... I guess one can consider the cube of earth an insulator, it's got a lousy insulation value per meter but it makes it up in thickness.

arethuza 5y ago
Don't think 15C is correct - looks more like 8.5C to 11C in England and 7C to 9C in Scotland. http://projectbritain.com/weather/average.htm http://projectbritain.com/weather/average.htm
- a_square_peg 5y ago
  You can look up ground temperature for your location here - https://weatherdownloader.oikolab.com/downloader https://weatherdownloader.oikolab.com/downloader. Layer 4 is between 1m to 3m depth beneath the surface.
  - arethuza 5y ago
    Apologies, I didn't appreciate you meant average temperature underground - that is definitely much warmer. We have a ventilation shaft for an old limestone mine near our house and on a cold day the warm air rising from it is very noticeable.
    - a_square_peg 5y ago
      I wasn't the commenter so no worries about apologies... just wanted to point out where you can find this information. :)
- Gravityloss 5y ago
  Sorry, I was wrong indeed, thanks for the correction

whirlwin 5y ago

We have an old house from 1988 located in Norway. Walking on the non-insulated wooden floor is very unpleasant. We will refurbish, and insulate under the floor, but it will not be anything near a passive house because of other construction shortcomings

deleted 5y ago
[deleted]
ricardobayes 5y ago
well try non-insulated tiles here in Spain haha. I don't know why houses are built to such a low standard in Spain. Even the UK had better quality constructions when I was there, and that says a lot (single glazed windows, poor insulation, weak plumbing)
- joking 5y ago
  no harsh climate overall so much less insulation is needed?
  - ricardobayes 5y ago
    Mainland Spain falls into the single digits at night at winter so definitely would need insulation, because there is also no central heating. People resort to heating with their aircons and portable heaters. I'm sad because I expected better infrastructure from 45% income tax at the highest bracket.
    - jakub_g 5y ago
      I come from Poland (sub-zero in winter; can be anywhere from -20C to +10C but typically 0-5C), but the winter I lived on the Spanish eastern coast was the coldest in my life: thin walls and windows, stone floor, no heating apart from little portable heaters, 5 degrees and rain outside. Now I live in French southern coast, the buildings are slightly better but still poor. In my place even with all heaters I have on max, I'm nowhere near as comfortable as in properly built and heated apartments in my home place (actually when visiting friends in Poland in winter I'm almost overheating!). Basically half of the year it's quite uncomfortable to stay at home for prolonged time: for ~4 months a year at winter; then again for ~2-3 months at summer (+26C at home with blinds down unless you put aircon on max for hours). Kinda suboptimal for WFH to be honest :)

leobg 5y ago

Exactly. Talking about thermal mass! There’s also the movement of underground houses. They use the ground for cooling in summer and for insulation in winter. Also it apparently makes for great noise reduction, in spite of having lots of windows, light and views. See the book “Recovering America: A More Gentle Way to Build”.

swader999 5y ago
Underground houses can be a nightmare dealing with water infiltration, codes and the power of soil.

poseva 5y ago

Really interesting. I've read about also "foundation insulation skirt" that allows you to create a warmer earth mass under the house. To be honest this was the biggest "complaint" that others had in regards of how a built the house, the general knowledge says that the earth is warm and you don't need to insulate against it... but the earth is maybe 5-10 degree, of course warmer than outside -5..-10 but still a lot colder than what we want inside the house, 20,21 degree C.

jaclaz 5y ago
That depends on how deep you dig, but of course going deep enough has a cost that may be far greater than the kind of insulation you used. The 20-25% of increase in cost is a good proxi (from my personal experience I would have said 25-30%), but, from an economical standpoint it should be compared with savings over time (in the same region). To give you an example in Italy, last time I calculated it, this 25-30% increase of costs corresponds - loosely - to the costs of heating for 20 years or so (bar the crazy increases in prices of energy that just happened), so it becomes more a "philosophical" choice than anything else to go for passive or almost passive.
- Sankozi 5y ago
  5% return per year (or more in case of price changes or regulations forcing you to change heating source) does not seem that "philosophical".
  - jaclaz 5y ago
    I don't understand fully your way of reasoning. A normal house costs - say - 200,000 "units" (dollars, euro, whatever). Making it "energy saving" costs an additional 60,000 units. In 20 years time you will be spending 60,000 units (3,000 per year) less for energy costs (and here we are assuming that ventilation and heating/cooling machines in the "better" house have the same maintenance costs than the ones in "normal" house, whilst usually, since they are more complex systems they tend to be more expensive). You essentially have a "break even" point 20 years in the future, from there onwards you start saving money. First thing, you need, now, 260,000 units instead of 200,000 (and not all people may be able to afford this). Then, if, for whatever reasons, you don't use the house at all times in these 20 years, or you need to sell it before that time you are unlikely to fully get the savings. Additionally, in less than 20 years time it is possible that someone comes out with a mega-para-hyper-ultra climatization device that makes yearly energy costs go down by (say) 90%. So, if you want to do the "right thing" from a climate/energy savings point of view, by any means choose to invest in a passive house, but it remains essentially a "philosophical" decision, not an economical one.

mrweasel 5y ago

> It is interesting that you insulate under the house. Isn't that pretty normal, I mean maybe not three meters down, but modern foundations are required to be isolated in many places. The legal requirement in Denmark is at least 300mm of isolation under the house.

8fingerlouie 5y ago
And that's not a new thing either. In my 1970's house we have 150mm insulation under the house from the original build, 150mm in the walls and 200mm on the roof. We added another part to the house a few years ago, and that was 300mm insulation in floor/walls/roof. Since the walls are made of brick with a depth of 7cm, it means the walls are 7+7+30= 44cm thick (plus some "slack") Even my 1980's summerhouse has 100mm insulation in floor/walls/roof.
jmrm 5y ago
That depends of the the place where you live. In middle to the south of Spain, the floor of houses are normally made of marble (or other ceramic material) slabs on top of a little layer of some glue cement, on top of the armoured concrete slab foundation, but on the north is a lot common to have wooden floors with air chamber of a similar size.
kitd 5y ago
It is indeed normal. I mentioned it by way of an intro to the unusual alternative I saw.

markvdb 5y ago

> It is interesting that you insulate under the house. Near our place in the countryside, required foundation depth is 1.4m to protect from frost heave. Use an insulated slab and that requirement goes away. The insulation keeps the heat in the ground. It protects the ground under the house from freezing. Nobody cares about regulations here, but they do about getting proper foundations...

lelanthran 5y ago
> The insulation keeps the heat in the ground. It protects the ground under the house from freezing. If it is preventing the ground under the house from freezing, then it is supplying heat to that ground. That's a energy-negative process - some of the heat you generate is used to maintain the warmth of the ground.
- jounker 5y ago
  Some of your heat is always going into the ground. The insulation prevents it from dissipating into the environment.
- markvdb 5y ago
  Au contraire, my dear Watson. Without under-slab insulation, the heat emanating from the ground below the house escapes very quickly. This heat we don't generate. It occurs naturally. This is about using the naturally escaping heat to keep the ground under the house from freezing, about raising the frost depth. This technique is especially interesting for holiday homes not permanently heated in northern climates. It's fairly standard in Scandinavia, up and coming in the Baltics, but less known in the US. In the US, it's usually called FPFS or frost protected shallow foundations. [0] [0] https://www.ncei.noaa.gov/products/land-based-station/frost-protected-shallow-foundations https://www.ncei.noaa.gov/products/land-based-station/frost-...

aaron695 5y ago

throw0101a 5y ago

> It is interesting that you insulate under the house. This is part of the building code in many areas: do a search for [under] "slab insulation". * https://www.buildingscience.com/documents/information-sheets/basement-insulation https://www.buildingscience.com/documents/information-sheets... * https://www.finehomebuilding.com/project-guides/insulation/insulating-a-slab-on-grade https://www.finehomebuilding.com/project-guides/insulation/i... It should be at least R-10 (RSI 1.8): * https://www.youtube.com/watch?v=O2dNp9bicSk https://www.youtube.com/watch?v=O2dNp9bicSk * https://www.youtube.com/watch?v=XKp0wRzvR-g https://www.youtube.com/watch?v=XKp0wRzvR-g

alksjdalkj 5y ago

> It is interesting that you insulate under the house. I think anyone who's gone camping will appreciate the need for insulation between the ground and whatever you're trying to keep warm - a good sleeping pad is crucial for keeping warm.

voisin 5y ago

Do you have a link on this? I’d love to read more about this.