Take care of the insulation product as homogeneous, Despite the fact that in genuine apps, rigid elements have joints and in many cases cracks. Hence, the U-price is usually higher than what It might be Should the insulation behaved like a homogeneous content. Reference two gives direction on calculating U-values. https://stevel417mgx4.thechapblog.com/33756127/the-best-side-of-energy-efficiency