Zero-energy Attefall. How would you have done it?

[fribygg]

I'm saying that what I mention applies to zero-energy houses, plus-energy houses, and passive houses.

All three of the above, with a focus on passive houses, I have built/designed an incredible amount of over the years.

Do you have any experience with small summer cottages? That's what the original poster is considering building...

 

[Ulltand]

 

[KungAnka]

Good aspect! We have an uninsulated log house and it has sunk over time.

Dad solved it with dowels made of round rods that he drove into the log wall, then he attached upright studs to the dowels. It has worked well, it was about 30 years ago that house was built.

 

[oliven1]

Do you have any experience with small summer houses? That's what the TS is considering building...

what's the difference?

 

[oliven1]

My dad solved it with dowels made of round rods that he drove into the log wall, then he attached standing studs to the dowels. It's worked well; it was about 30 years ago when that house was built.

exactly these kinds of solutions that absolutely do not work if you want to build energy-efficiently.
it creates enormous cold bridges.

insulation must be completely separate from the studs, absolutely no studs in the insulation.

 

[Ulltand]

precisely these kinds of solutions absolutely do not work if you want to build energy-efficient. they become enormous thermal bridges. insulation must be completely separate from the studs absolutely no studs in the insulation.

A thermal bridge is nothing more than a small area with a poorer U-value. The total impact on the U-value is therefore limited. The U-value for a 195 mm stud in the case of a thermal bridge is about 0.7. So, roughly like an extremely good window. Sometimes it almost seems like many people think it's over if there are thermal bridges. But of course, if you want to get down to zero energy, these should be avoided.

 

[Ulltand]

what is the difference?

As I have pointed out earlier, an important difference is that you don't want 50 cm of insulation in a small house.

 

[oliven1]

A thermal bridge is nothing more than a small area with a poorer U-value. Therefore, the total impact on the U-value is limited. The U-value for a 195 mm stud in the case of a thermal bridge is about 0.7. So, like a really good window roughly.

Sometimes it almost seems like many people think it's over if there are thermal bridges. But if you want to go down to zero in energy, these should indeed be avoided.

then one hasn't grasped the importance of avoiding thermal bridges.
a stud in itself is not close to 0.7

having, for example, a stud frame of 195mm between the insulation does not have a limited impact on the house.

 

[Rabbithole]

One usually estimates lambda 0.1-0.12 for spruce/pine

195mm stud then becomes u=0.61

 

[Ulltand]

Speaking of small FTX units, this one from PAX is a smart variant. Mount it in the WC, with an air exhaust channel to the living room and a carbon filter fan above the stove.

 

[KungAnka]

exactly these kinds of solutions that absolutely do not work if you want to build energy-efficiently.
they create enormous thermal bridges.

insulation must be completely separate from the studs; absolutely no studs in the insulation.

Enormous thermal bridge 😀. Say the studs are spaced c-c 60 and that each stud is 2.70 and has 4 pcs 20 mm dowels. That becomes 2.5 dowel/m2 or 7.8 cm/m2.

How long the part of the dowel is "visible," i.e., the part between the end embedded in the log wall and the end inserted into the stud (i.e., the free part that allows the log wall to move freely compared to the stud), depends on how thick the insulation is. In the insulation layer, 0.78% of the wall is solid wood, the rest is insulation. No enormous thermal bridge.

Or maybe you thought you would rigidly fasten the stud against the log wall? Then you've probably missed the technical construction, the log should be able to move.

 

[oliven1]

Huge cold bridge 😀. Say the studs are placed at c-c 60 and each stud is 2.70 with 4 pieces of 20 mm dowels. That becomes 2.5 dowels/m2 or 7.8cm/m2.

How long a part of the dowel is “visible,” i.e., the part between the embedded end in the log wall and the end inserted into the stud (the free portion that allows the log wall to move freely compared to the stud) depends on how thick the insulation is. In the insulation layer, 0.78% of the wall is solid wood, and the rest is insulation. Not a huge cold bridge.

Or did you perhaps think one should hammer the stud tightly against the log wall? Then you may have missed the technical design; the log is supposed to be able to move.

the insulation should be completely unbroken.
this is how we always build passive houses to meet both insulation and airtightness requirements.

 

[fribygg]

In the long term for a modest permanent residence, but more now as a summer cottage with the possibility to heat temporarily during the winter.

The insulation should be completely unbroken.
This is how we always build passive houses to meet the requirements for both insulation and airtightness.

How do you build summer cottages of about 20-30m2 that will eventually become permanent residences @oliven1?
I think well-insulated timber houses on pilings or a proper stone foundation with a stove for heating and perhaps an air source heat pump if you accept being dependent on electricity is an excellent idea. However, I am very doubtful if it's economically feasible to make it a Zero-energy house.

 

[Rabbithole]

The insulation should be completely unbroken.
That's how we always build passive houses to meet the requirements for both insulation and airtightness.

Completely unbroken insulation is practically impossible. It's good that you're building carefully, but the whole concept doesn't fall apart because of a few minor thermal bridges. It's the overall picture that counts.
And thermal bridges have nothing to do with the airtightness of the house.

Many small streams, as they say.

 

[oliven1]

How do you build summer cottages of about 20-30m2 that in time will become permanent residences @oliven1?
I think well-insulated log houses on pillars or real stone foundations with a stove for heating and maybe an air heat pump if you accept being dependent on electricity is an excellent idea, however, I am very doubtful whether it is economically viable to make it a Zero-energy house.

completely agree, hard to make a small log house a zero-energy house.
that's roughly what I've been saying all along.

doesn't mean log houses are bad in any way, they have other qualities.