javaw -Xmx512m -jar "C:\Program Files\Sweet Home 3D\SweetHome3D-2.0.jar"
It is well.

javaw -Xmx1024m -jar "C:\Program Files\Sweet Home 3D\SweetHome3D-2.0.jar"
SweetHome3D window is displayed some seconds and then is closed, as for SweetHome3D-2.0.exe and SweetHome3D-2.0.jnlp