The recent media outrage about where Senators "reside" seems to have all but ignored the legal definition of "residence". That definition is fairly straightforward -- the fact that the Senators under attack have not gone to that definition to show they are residents of their home province or territory is very telling.
"Reside" does not necessarily require physical presence. It is more a question of where a life is centred about. Where are taxes paid, what type of drivers licence is held, what's the mailing address for credit cards and that sort of thing.
So I may think of Vancouver as my "home" but if I have an Ontario driver's licence, pay my taxes out of Ottawa and get my VISA bill to an apartment on Elgin Street (in Ottawa) I reside in Ottawa.
The Federal Court of Canada has ruled on numerous occasions that "residency" does not necessarily mean "physical presence". It can include time spent outside of the jurisdiction of residence if during that period the mode of living was centralized in the jurisdiction of residence, i.e. where the applicant's spouse, children, home, bank accounts, major assets etc.
The Senators being challenged can easily answer all concerns by pointing to where they filed taxes, hold licences and pay bills. (Or these things will prove they are non-residents).