Hello!
I am going to do a U-value calculation for a basement wall underground. I've heard that you can benefit from the wall being underground, as the soil should also help to insulate.
So, as it stands now, it is as follows:
Insulating board at 70 mm with a lambda value of 0.036
Concrete edge beam inside at 360 mm with a lambda value of 1.7
According to my calculations, it becomes:
Riso: 0.7 / 0.036 = 19.44
Rbet: 3.6 / 1.7 = 2.118
Utot = 1 / (19.44+2.118) ==> 1 / 21.56 = 0.46
Is this calculation correct?
And as I mentioned above, is there a factor that can be added because the basement wall is underground. I'm considering this as I would need to achieve a slightly lower U-value.
Very grateful for help!
I am going to do a U-value calculation for a basement wall underground. I've heard that you can benefit from the wall being underground, as the soil should also help to insulate.
So, as it stands now, it is as follows:
Insulating board at 70 mm with a lambda value of 0.036
Concrete edge beam inside at 360 mm with a lambda value of 1.7
According to my calculations, it becomes:
Riso: 0.7 / 0.036 = 19.44
Rbet: 3.6 / 1.7 = 2.118
Utot = 1 / (19.44+2.118) ==> 1 / 21.56 = 0.46
Is this calculation correct?
And as I mentioned above, is there a factor that can be added because the basement wall is underground. I'm considering this as I would need to achieve a slightly lower U-value.
Very grateful for help!
It means quite a lot for the u-value indeed. (Unfortunately, I am not home and can't check my old papers, so I can't be of any help right now.)
It might be a good idea to add to the post what type of soil you have, as it varies quite a bit. (For example, peat and granite don't exactly have the same thermal conductivity if you go to extremes...)
On the plus side, you can also add a transition resistance on the inside of the wall.
On the minus side, you should take into account that the wall is not entirely homogeneous. (i.e., you probably have joints in the insulation where a little extra heat easily leaks out, and the total u-value should be corrected for this.)
It might be a good idea to add to the post what type of soil you have, as it varies quite a bit. (For example, peat and granite don't exactly have the same thermal conductivity if you go to extremes...)
On the plus side, you can also add a transition resistance on the inside of the wall.
On the minus side, you should take into account that the wall is not entirely homogeneous. (i.e., you probably have joints in the insulation where a little extra heat easily leaks out, and the total u-value should be corrected for this.)
Thank you for taking the time to respond!
The land around the house facing the walls consists of stone, sand, and gravel.
Can I then add some factor in this calculation Utot = 1 / (19.44+2.118) ==> 1 / 21.56 = 0.46
for stone, sand, and gravel to lower the value? If so, is there a good site where one can find approximate values?
The land around the house facing the walls consists of stone, sand, and gravel.
Can I then add some factor in this calculation Utot = 1 / (19.44+2.118) ==> 1 / 21.56 = 0.46
for stone, sand, and gravel to lower the value? If so, is there a good site where one can find approximate values?
Hi,
I think you can do your calculations here http://www.rockwool.se/beräkningsprogram/energiberäkning
I think you can do your calculations here http://www.rockwool.se/beräkningsprogram/energiberäkning