Inside / Outside of a shared wall between two zones

Hi there. Simple question.

I have a wall construction which is asymmetrical, it has insulation on the outer layer and thermal mass on the inner layer. How is this treated when I assign this construction to a shared wall between two zones? Which one gets the inner side of the construction? Or does EP calculate as both having the inner side towards each zone?


A or B?

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For internal walls the shared wall has to have the same construction. In the calculation process it relates to each of the walls “independently”, meaning that the first layer of the wall is on the “external” side of the wall.
So the answer is that non of your options is right. You are missing option C, in which option A has to sub-cases. The one you draw is correct for Zone 2 and you need a sub-case where you mirror the section for Zone 1.


Thank you,

Wouldn’t my drawing A) be right for Zone 1 calculations? (Inside layer towards the zone and outside layer towards the outside farther away from the zone? and Mirror that for Zone 2 calculations?

I guess it would be better to make a symmetrical construction in this cases where walls are shared?

You are right. For internal walls you need to have a construction that is symmetrical for both sides (say, plaster+brick+plaster). In this way you don’t have to worry about your question since it will fit both conditions/zones.

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