Difference in U Value calculation between PHPP 9 and PHPP 10

[Liz King]

Wondering if anyone can help with a PHPP 10 query.  I’ve imported a project from PHPP 9, and I am finding that, for a particular warm roof build up, the u-value calculation is coming out much lower than that given for the exact same build up that I had in PHPP 9.  No change to thermal conductivities, orientation, adjacencies or thicknesses. The difference is in the region of 0.04W/(m2K), which feels quite significant.  Does anyone have any idea why this is the case or has experienced something similar in migrating from PHPP 9 to PHPP 10?

[Rory Kennon]

Hi,

Apologies and I may be a bit late to the game on this one.

I have looked at the example files for PHPP 9 and 10 which have the same U-value entries and can see no difference.

It may be that the ‘Adjacent to’ dropdown is incorrect and not set to outside air, but a change of only 0.01W/m2K is the only difference when toggling this setting?

If not already done so I would try manually entering the figures to rule out any rounding issues.

[Author]

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