Yes.
No. Regular bathroom mirror with built-in cabinet.
Is the fogging happening through what we assume is standard means? Like the mirror is colder than the humid warm air, causing the water vapor to crash out onto the surface of the mirror?
I’ve been assuming something is ‘different’ about the summer situation…but…
Is something unexpected happening in the winter situation where you are not getting as much condensation on the mirror as we should expect?
Is someone coating the mirror in the wintertime with antifog material, and not doing it in the summer time?
Yes. Standard means.
As far as the winter situation being different…sort of. It’s not so much the winter that’s affected by it as the summer is, but it’s the same circumstance. It’s more that the summer has more condensation than expected for a specific reason and this is less of a thing in the winter.
No antifog material involved.
Since there hasn’t been any additional questions in a few days, I’ll drop a small hint:
There are three full baths in our home. Although I don’t shower in the other two, if I did, one would have the same mirror fogging issues, and one would not.
Is the one you use on an upper floor? Ground floor? Basement?
Basement-ish.
In Chicago, many buildings are laid out where the first/ground floor is about one-half story above ground and the basement is sometimes occupied by an English garden style apartment where that living space is a half-story below grade but otherwise has standard egress doors.
Our condo occupies two floors. The top floor sits half-story above grade with two entrances/exits. The bottom floor (no egress other than windows that are at street-level), is a half-story below grade, like and English garden without doors.
The one I use is on the bottom floor.
Do you take the same length of shower in the summer than in the winter?
Do you take them at the same time in the summer vs in the winter?
Is it your shower that is fogging up the mirror?
Is there a house guest that is there in the summer but not the winter?
Yes
Irrelevant
Yes
No
Another hint:
The key part of the puzzle is the location of the bathroom as established in the above post. It is directly connected to two factors that explain why the mirror fogs up more in summer than winter despite the thermometer being set to a higher temp in summer.
Figure out those two factors, and the puzzle is solved.
Is the location of the heating /cooling system relevant?
Is the mirror attached to a wall that has the outside on the other side?
Does this involve steam pipes at all?
There are a lot of parts that go into an HVAC system, but if you’re referring to the unit that contains the furnace and AC compressor, then no.
No to both.
Not sure this has been asked: Is there a window involved?
No window involved.
Does it have to do with the fact that you are heating the home in winter and cooling it in summer?
Certainly.
Does hot or cold air blow on or near the mirror?
Not near enough to itself matter for this puzzle. It could be a contributing factor at making the mirror steam up worse than otherwise, but it would only be a booster for the main reason this happens.
In other words, even if the HVAC isn’t running at that moment, the scenario is still observed.
can you confirm that the temperature difference between the steam and the mirror is greater in the summer (causing more condensation), than the temperature difference in the winter?
Is the greater condensation in the summer related to a larger temperature difference between the steam and the mirror than is found in the winter?
Yes to both questions.