[poseva]

I've also built a simple and small (99sqm) PassivHaus in Romania, 5 years ago. Everybody, and I mean everybody from family to friends called me nuts, but I've got my payback this winter when the energy prices went trough the roof and I'm just slightly affected.

The house is elevated from the ground on 12 concrete columns so that I can insulate under the foundation beams using glass foam, insulation on walls is 30 cm of EPS graphite, underfloor 45 cm EPS and on the roof, 50 cm and the orientation is full on south. For heating it consumes about 1500-2000 kWh per year (December, January, February and a maybe a small part of March)

What is the big difference between houses built in North America and Europe is that the European houses are built using concrete and masonry which give them a lot of thermal mass which is crucial to this kind of builds.

Have a look here [0], this is the first PassivHaus in my area and is nicely documented. The cost of building a PassivHaus in my country typically goes about 20-25% more than a traditional one.

[0]: http://www.sdac.ro/site/archives/category/passivehouse

[jmrm]

People doesn't give the massive importance the isolation has. Some years ago we remodelled our home and added XPS (Extruded Polystyrene) to insulate the roof of the house. After that we use the AC only three or four days in the year, and before that we had to use it at least a complete summer month. That house is in the south-interior of Spain, so heat is no joke here.

If somebody are constructing or remodelling any house I recommend it to add any insulation they can in any shape, in less than five years you'll recover what you spend, and if you add PV panels for electricity or a thermosiphonic system to heat water, you'll recover the investment in about 10 years, with a healthy amount of available health in the devices to continue saving money with a proper maintenance.

[franciscop]

What people definitely don't give enough importance is CO2 buildup as well. The more isolated a place is, and smaller, the more environment friendly it is BUT the more likely it is to build up CO2, which leads to headaches.

I installed a CO2 meter both at my current home, and at my parent's home for when I go back for Christmas. In my home, it's a fairly big open place so it takes ~2 days of closed windows (0-3C outside) to reach 2000PPM (recommended under 1000, above 2000 starts affecting you, 5000 is the legal limit[1]). However, at my family home where I grew up it's a tiny room and it reaches 3000-4000 just by sleeping there with the window and door closed. So the headaches of "visiting family" might in big part be explained by this.

PS, incidentally in Spain!

[1] https://www.kane.co.uk/knowledge-centre/what-are-safe-levels...

[fouc]

It seems like historically people underestimated the insulation value of polyurethane because apparently it doesn't necessarily do well on the conventional R-value score.

Apparently a solid inch of sprayed polyurethane can provide 90% insulation, and 2 inches gets you to 99% insulation.

https://www.monolithic.org/blogs/presidents-sphere/r-value-f...

[fullstop]

> That house is in the south-interior of Spain, so heat is no joke here.

I looked up a few areas (Ciudad Real) to see what you meant by heat, but it seems quite similar to a good portion of the northern USA. This makes sense, I suppose, given the similar latitude.

[SOLAR_FIELDS]

Insulation is so, so important. I work out of my garage currently and Texas winters get reasonably chilly and of course summers are hot. I'm lucky enough that my garage is actually under a room in my house such that it's insulated (as you imply, roof insulation is one of the most important places to insulate). Even simply adding padded insulation and trim to the exterior door and garage door made it viable enough to stay cool in the summer with zero extra cooling and warm in the winter with a small infrared heater.

[voisin]

What about windows? I find buildings with few or small windows to be unmanageably dreary, but the math works out that no matter how insulated you make the walls if you have a good amount of glazing on the walls the effective R value drops quite low.

[kitd]

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.

[mrweasel]

> 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.

[poseva]

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.

[leobg]

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”.

[alksjdalkj]

> 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.

[markvdb]

> 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...

[throw0101a]

> 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...

* 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=XKp0wRzvR-g

[Gravityloss]

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.

[whirlwin]

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

[voisin]

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

[madaxe_again]

We’ve just built a 45m2 log cabin to passive standards here in Portugal - heavily insulated in walls, floor, roof, lifted off the ground on concrete columns, double glazed, only heat source is a 2.5kw log stove. Everyone here (who all live in uninsulated concrete houses heated by open fireplaces) said we will freeze in the winter, roast in the summer. We situated the house on a north facing slope, to minimise sun exposure in the summer. Means little direct light in the winter, but we think (have yet to experience a summer in it) the balance will be good.

As I write this, the stove is out, having burned out overnight, it’s -11 outside, and 25 inside. We are getting through a ridiculously tiny volume of firewood compared to when we were living in a more traditional house for here - less than ⅛ the volume.

Insulation works. It’s also cheap. I don’t understand why people would build new structures without it.

[phillc73]

It would be very interesting to learn more about this build. Was it something pre-fabricated (I've seen "kit" log homes advertised) or something completely custom?

[mschuster91]

> Insulation works. It’s also cheap. I don’t understand why people would build new structures without it.

People are a bit sceptical about many insulation forms... plastic-based stuff is either a fire hazard (see Grenfell Tower) or extremely toxic waste (if it has been treated with fire suppressants), asbestos is completely banned for good reasons, and rock/glass wool can also spread nasty ultra-fine dust.

[voisin]

What do you do for fresh air? We have a very well insulated cabin heated by fire, but find the CO2 builds up, particularly overnight with no doors opening, and if we aren’t very quick to close the fire once it gets going, PM2.5 can jump quickly.

[throw0101a]

> What is the big difference between houses built in North America and Europe is that the European houses are built using concrete and masonry which give them a lot of thermal mass which is crucial to this kind of builds.

Here's a 500 sq. m. (5000 sq. ft.) house built with heating equipment that uses 1800W (the equivalent of a hair drier):

* https://www.youtube.com/watch?v=_vul4vMFdkA

The same person building his own personal home up to Passive House standards:

* https://www.youtube.com/watch?v=mBOvflXoWlw

You do not need concrete† and masonry to make homes efficient. Switching from using 2x4s @16" off centre (OC), to 2x6 @24" OC ("advanced framing") would allow for less wood use, less thermal bridging, and more cavity space for insulation.

† It should be noted that concrete creates a lot of CO2 emissions, as does baking bricks. Growing wood on the other hand is a way to sequester carbon.

[poseva]

I agree, you do not need concrete and brick but you also need to take into account the local traditions. For ex. building a wood house (framing or CLT) would have cost much more than concrete and bricks and was also much more prone to errors because of the builders lack of experience, at least in my area and country.

Recently in Romania it really took of building houses using CLT (cross-laminated-timber) but it costs so much more than a regular brick and mortar house that few people afford it.

When -15 outside and 20 degrees inside, my house requires 2000W to keep the balance. This kind of simulations are done using PHPP package from PassivHaus Institut.

L.E. What I wanted to point out, thermal mass can have a huge impact on the house energy footprint.. to give you an example, today and tomorrow will be sunny days and this will drive my interior temp to about 23-24 degrees, this heat will heat-up the masonry and slabs and then give me back the heat in the next days when there will be no sun.

[bluGill]

Modern codes have moved back to 2x4, then they put continuous foam on the outside of that to make the total the width of a.2x6 wall. Wood is not a great insulator and you have to have some

[Mvandenbergh]

Moving insulation outside the frame also helps reduce the effect of thermal bridging although with timber that's not so important as it is with steel.

[oldsecondhand]

High thermal mass is definitely more energy efficient in the summer, when you can "store the cold" from the night into the next day.

[k__]

A friend of mine, who is an architect, told me the technology is ripe to build houses that produce even more energy than they consume, but people simply don't want to live in them.

The article talks about "using the best windows", the problem my friend saw in many of such houses was simply that the dwellers would either open the windows too often, losing all the heat, or feel miserable because they weren't allowed to open the windows. A pure psychological effect of course, even with the best ventilation people still had the urge to open a window and felt bad if they couldn't.

[spookthesunset]

> A pure psychological effect of course, even with the best ventilation people still had the urge to open a window and felt bad if they couldn't.

I wouldn't want to live in a house where I couldn't open the windows all the way. Near-perfect energy efficiency is something to strive for but there is something to be said for being able to open the window and get a nice breeze blowing through the house.

Even if it isn't the most energy efficient it's okay with me. I mean if we really wanted to get good energy efficiency we'd just remove all the windows completely. But we don't because we design building for the enjoyment of humans, not just for energy efficiency.

[throwaway984393]

I recently lived in a house with no external ventilation in one big room. Huuuge windows looking out onto a huge backyard full of trees and flowers. Yeah I missed being able to open the window and hear the birds. But then when lawnmowers started buzzing and dogs started barking, and later when winter hit, I was quite glad for the peace and quiet and no need to open them!

[driverdan]

> the technology is ripe to build houses that produce even more energy than they consume, but people simply don't want to live in them

It's called solar. Unless the house has a small footprint most can fit enough solar panels to more than cover their energy use.

[spookthesunset]

> A pure psychological effect of course, even with the best ventilation people still had the urge to open a window and felt bad if they couldn't.

I wouldn't want to live in a house where I couldn't open the windows all the way. Near-perfect energy efficiency is something to strive for but there is something to be said for being able to open the window and get a nice breeze blowing through the house. Even if it isn't the most energy efficient it's okay with me.

[changoplatanero]

how do you ventilate without losing all the heat?

[mariushn]

Salut! Could you please share more info / photos / tips, besides the sdac.ro link? How high is the elevation? What kind of heating do you use? How do you refresh the air? (opening the windows or heat recovery system) Thanks

[AtlasBarfed]

So with home solar panels and storage getting cheaper and cheaper and better and better, where is the optimization point of investing in better insulation vs just buying more solar panels?

Especially if the solar panels may produce profit on sunny mild days about 40-50% of the year if there is reverse metering and the like?

[maxwell86]

Insulation beats solar panels. It’s not only much cheaper to get, but also to maintain.

The body heat of a family of 4 is enough to heat a well insulated house.

Solar panels are there to supply electricity for use. The last step of passive houses are zero-energy houses, which means that they don’t get electricity from the grid.

[goodpoint]

> small (99sqm)

Is that correct? 99 is not small at all.

[poseva]

Small in comparison with a typical single family homes that goes >150 sqm in my area. I completely agree with you, 99 sqm is more than enough for a 4 people family.