Yes, You can import Archicad models into Ecotect. In ArchiCAD open a 3D window of your model, save your model as .3ds format file. In next dialog box, select material radio button and set the units as per your preferences. Import 3D CAD geometry in Ecotect and start your analysis.

With version 5.6 we (ArchiCAD users) may be able to export IFC 2X3 format into ecotect.

Hope this helps!

In addition to above, yesterday I discovered two new ways of importing ArchiCAD models in ecotect. First is DXF and other is wavefront .OBJ. both worked well as an import, but i am not sure, how accurate they will be for analysis. Still exploring.