[TRNSYS-users] Massless Layer

[Camila Davila Valdebenito via TRNSYS-users]

Hi TRNSYS users!
I'm simulating a building and I need to create a massless layer. I've 
calculate the overall heat transfer coefficient that I need for some "X" 
wall (6.6581 W/m2K in this case). The massless layer requires a thermal 
resistance in [hm2K/kJ], which is the reciprocal of the heat transfer 
coefficient. Doing this, I get R=0.0417203 [m2Kh/kJ].
When I create a wall with this layer (and this R value) the wall type 
manager shows me an U value of 3.123 [W/m2K] (totaly diferent of the one 
that I need).
Does anyone knows how TRNSYS calculate this? or what is the right unit 
conversion?
Thanks for your time