I'm on the verge of starting construction. I have yet to decide what material to use, and the discussions in the forum aren't very helpful—everyone is advocating for their chosen option! There's a lot of focus on U-value here, similar to how people once only talked about the number of pixels in digital photography, neglecting other variables like lenses when it came to the final quality.
Bertil Harström wrote back in 2005 in "Arkitekt" (December): "U-value calculations are a theoretical model that doesn't account for the dynamic effects present in reality." Shouldn't we instead be discussing the "inertia" of the material? This would put blocks such as Maxit's 400 DSM block (with a U-value of 0.3) in a better light. What are the pros and cons? I would gratefully accept advice before I decide on building material.
Bertil Harström wrote back in 2005 in "Arkitekt" (December): "U-value calculations are a theoretical model that doesn't account for the dynamic effects present in reality." Shouldn't we instead be discussing the "inertia" of the material? This would put blocks such as Maxit's 400 DSM block (with a U-value of 0.3) in a better light. What are the pros and cons? I would gratefully accept advice before I decide on building material.
It would likely require a significant amount of heat storage capacity before it can compensate for a noticeably lower U-value (in terms of annual consumption). It's mainly about storing excess heat until it is needed more. In a typical residential house, there isn't much excess heat during the coldest season (unless the construction has very good U-values 
), and during spring and autumn, heating costs aren't that high anyway. However, it can be beneficial to have a thermally sluggish house to, for example, avoid needing to add as much extra electricity during a short cold snap if you're using a heat pump. (Plus, you could also consider that a thermally sluggish house makes the climate a bit more pleasant in the summer.)
), and during spring and autumn, heating costs aren't that high anyway. However, it can be beneficial to have a thermally sluggish house to, for example, avoid needing to add as much extra electricity during a short cold snap if you're using a heat pump. (Plus, you could also consider that a thermally sluggish house makes the climate a bit more pleasant in the summer.)0.1 Or 50% worse if you prefer.
Or to give an example for 150m2 outer wall at -20 outside and +20 inside:
150*(20-(-20))*0.2 = 1200W
150*(20-(-20))*0.3 = 1800W
What it ultimately comes down to in terms of cost depends on the location, heating method, and to some extent the heat storage capacity you mentioned.
Or 50% worse if you prefer.Or to give an example for 150m2 outer wall at -20 outside and +20 inside:
150*(20-(-20))*0.2 = 1200W
150*(20-(-20))*0.3 = 1800W
What it ultimately comes down to in terms of cost depends on the location, heating method, and to some extent the heat storage capacity you mentioned.
In new construction of permanent residences, the total amount of energy supplied per m^2 and year has been limited. This shall be reported in the form of an energy declaration to obtain a building permit. It can be difficult to meet this requirement for total energy consumption if you have walls with a U-value of 0.3... (And thus obtain a building permit) Instead, aim to come under 0.2 (at least). Then, it is good to have heat storage capacity in the construction (thermal inertia) which evens out the worst temperature peaks and troughs, but I believe this inertia does more for comfort than for the total energy consumption? In any case, you must compensate for the average heat loss over the year and with poor insulation such as 0.3 in the walls, it will be many kWh to push into the house. The average annual temperature where I build in Västernorrland is +4 degrees, and it is against this temperature that insulation should work on average over a year... Take the above example with 150m^2 wall: 150*(21-4)*0.2=510W *365 days*24h=4470kWh 150*(21-4)*0.3=765W*365 days*24h=6700kWh This gives 2230kWh/year in increased energy consumption... (very roughly calculated)