I wrote about this on the main website. Open plan living is not ideal for domestic cats. This is because it is too open. Cats need, if one is going to be an excellent cat owner, at least one place to hide. In open plan living there are less opportunities to hide. Of course it depends upon the details of the interior space and the owner's preferences. Some owners like totally sheer, clean areas with minimalistic lines et cetera. It is these sorts of interiors which are not ideal. The need for a domestic cat to hide, however, is not that pressing in my opinion. It may occur in multi-cat households where one cat is perhaps bullying another and the submissive cat is timid. Or the general ambience of the house is not particularly healthy with respect to a domestic cat. The owner might not be that good. There may be too much activity or too much noise. There may be a stranger in the house for a while. There are numerous factors which can generate an uncomfortable ambience for a cat