I have roof made by scheme from images. Both should be same, just different angle.
I have 20cm of space yet to fill. How can I calculate conductivity in W/m2K if i fill missing 20cm of space with 20cm of mineral wool or if i fill just 10cm and leave 10cm of air. I would like to know this because i want to know heat loss ratios between walls, roof and windows to rationally spend same amount of money to get best insulation for my house. Maybe ill leave this empty and buy better windows, or maybe take thicker insulation for walls. Notice that some insulation already exists, 12 cm of glass wool and 2 x 2.5cm of wood. My question is about remaining 20 cm of space.
[Update]
Several facts that matter here, this object is in Croatia, see temperature graph below.
It will serve for 4-seasonal living, insulation required to keep heating bill lover in winter and to prevent heating during summer when temperatures can be sometimes 35-40 Celsius.
Best Answer
Where are you located and is this for a 4-season living space?
You want to insulate your ceiling to keep the warmth in (if in a climate with a heating season) or keep the heat out (if in a climate with a longer cooling season). Assuming you are in a region where you need to heat your house.
You will lose more heat through an uninsulated ceiling than you could ever recover through better wall insulation or better windows.
Make sure you extend your insulation over the exterior walls to the edge, otherwise you will lose a lot of heat through the corners at the exterior wall.