Question is- 1) Does department head wants to be involved anyhow in these "business affairs" and second problem 2) Somebody in the public can think that department head is also "not fully transparent" or "biased" so to say, so that this sunlight may be not enough. "Comparable prices" are also relative stuff, depends on who tells what. Are you going to hire real estate experts for this and document prices legally ?

@AgniusVasiliauskas 1) Department head is paid to do these things. If a conflict of interest complaint were made, it would definitely involve the head. 2) Someone can always complain about anything. The lease isn't an issue unless the terms were favorable to the student for some reason. Find comparable kitchens and cite their prices and the kitchen sale becomes a non-issue.

with a note saying that there is nothing for the department head to do other than take note that the transaction happened and that all sides have made efforts to ensure that they do not affect anyone's judgment ... I wonder if they would take the word of the 2 affected parties on the innocuity of the transaction. Indeed the very effort to present it as such might arouse suspicion. Plus the fact that the new tenant (professor) must have gone to the apartment of the old tenant (their PhD student) . . . Does anyone else see a danger with this ?

@Trunk you misunderstand. The purpose of the email is not for the Head to read it and confirm that it's a reasonable plan. The purpose is for it to be witnessed evidence that this was thought about and steps were taken before anyone made a complaint. If a complaint were made and parties just claim "oh yeah ... we definitely thought about it. Look here's a letter that I wrote", then the accusers can say "BS; you wrote that 5 minutes ago, as a cover up".

Yes, like @Brondahl says. The department head (or whatever other official at the university you may want to choose) is only there to receive the document and archive it, with a time stamp.

@AgniusVasiliauskas Indeed having a comparable quote that illustrates typical going rates for kitchens attached to the email is even better.

It's been a while since I left Germany (assuming this is Germany), but the relationship between professors and their PhD students is often more akin to colleagues and being invited for e.g. a group barbecue would not raise any eyebrows. I doubt anyone would bat an eyelid at a professor having been to a PhD student's apartment (or vice versa).

@Brondahl But why should the Head just accept this all as bona fide ? Any significant non-academic transaction between supervising professor and PhD student is a red flag to a Head, surely ? It is something best avoided. University accommodation officers could deal with this better. You can't have supervisors going along to their students' apartments to view and price apartments.

@Trunk read my comment again. This email has nothing to do with the Head accepting anything. He's there as a witness to the existence of the email; not a judge of its content.

The Head is acting, essentially, as a "notary public". And you could equally just use a professional notary instead.

Sure. But wouldn't the Head have plenty to say about all this kind of thing ? Pieces of paper are fine if everything else is right. Here it just ain't. Not appallingly of course. I believe no harm is being done in OP's case. But what if this kind of thing becomes commonplace ? It does force anyone in a senior role (e.g. Head) to ask themselves if there might be a better way to effect the same essential transaction than having professors hustle directly off their PhDs/fellows/etc. Academia really is incestuous enough without people mixing outside the campus and engaging in non-academic trade.

@Trunk Why would it be a problem that the supervisor has been to their PhD student’s flat? I’m not aware of any part of the world where PhD students are not allowed to socialise with their supervisors at any location they choose. I’ve certainly visited several PhD students at their flats for social events where their supervisors were also present, and I’ve never even conceived of the notion that this could be problematic in any way.

The moral hazards of supervisors visiting their PhDs at their apartments are quite obvious. For that matter, the moral hazards of PhDs (or undergrads) visiting their supervisors at their homes are equally clear. But let's look aside from moral hazards for a moment. Let's consider what's healthy for both professors (yes, they are human) and PhDs. Both need a life away from their jobs. While a professor may seem better advantaged in building themselves a life (higher salary, the confidence that comes with achievement and age, etc), it may not be any easier for them to say hello to a stranger.

[contd...] This relational challenge won't be met by their confining their social engagement with people at work: that will simply crystallize an inadequacy for want of exercise. A similar challenge faces the PhD researcher: they have less standing and much less resources - not to mention much less time - to provide themselves with an amenable social life. And all the while, their fires of ambition are burning away . . . getting involved socially with a professor might be tempting for a PhD. But it won't solve either the research challenge nor their need for emotional balance.

@trunk There is a difference between having a close social connection (or, god forbid, an affair) and coming to someone's house for a ten minute inspection of a kitchen. In any case, all of my graduate students have been to my house for dinner (not individually, but as a group), and that is pretty typical. I don't think anyone would consider this inappropriate.

Until someone lets the whole team down by exploiting their inside information to advance a pedestrian academic career or provide emotional distraction. Then the university management imposes a set of rules that penalise the 99% for the transgressions of the 1% . . .

@Trunk That seems quite ridiculously dystopian and pessimistic. The “moral hazards” of socially visiting a colleague’s home are very far from obvious to me, because I don’t believe there are any. This may in part be down to differing cultures, but at my university, supervisors and PhD students are first and foremost colleagues, and it is the norm here for colleagues to socialise. For decades, our professor has hosted a summer party at her house every year for all students and faculty (including PhDs) – what “inside information” would one gain by attending such a party?

I might ask what real good does it do for PhD candidates to go to these affairs. No PhD I met was starving or short of the price of a drink. Bonding? Surely academic research is already far too intimate in that staff and students working together see one another's human strengths and weaknesses without even trying to study them. It's not a reason, saying that other people are doing it, Oppenheimer did it, Bernal did it or whatever.

Let's just all agree that we disagree about this. It is certainly common for faculty to have dinner parties. If @Trunk doesn't see value in those, they're welcome to neither host nor participate. The rest of us can enjoy occasional social interaction.