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Old 08-10-16, 01:01 PM   #28
Mobile Master Tech
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THIS LINK and also THIS ONE shed some amazing light on real-world insulation.

Whether for a storage tank or a building envelope, the diminishing returns of extra insulation and the dramatic degradation in its effective R or U value with even tiny amounts of uninsulated/less insulated area are surprising. So much so, that improving more poorly insulated areas (by using low-e windows, fixing insulation gaps around obstacles, designing without thermal bridges, etc) is WAY more important than adding extra insulation past a certain point.

An uninsulated pulldown attic staircase (or gaps around insulation) of only 1% of the total area increases heat flow for an attic with R30 by around 25%, while adding insulation to R50 reduces heat flow by only about 5%!

I will be making sure there are no thermal bridges between the bottom of my tank and my basement slab....
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