Humidifyer at play here?
Actually, I’m thinking you have a swamp cooler turned on during the summer. Is that correct?
No to both.
Let me just spit ball here.
In the summer the cooler air sinks to the bottom of the building, making the bathroom (and mirror) cooler…lets just say in the 60’s.
In the winter the heat kicks on and keeps the lower level (and mirror) warmer, (lets say lower 70’s as an example). Even though the lower level is cooler than the upper level in the winter, there is sufficient mixing that your lower level is actually warmer in the winter than it is in the summer.
The steam temperature is the same year round.
So you get more condensation in the summer
That is a contributing factor. But that alone doesn’t explain it.
But you’re on the right track in that the downstairs temperature in the summer can reach temperatures lower than what is typical for the winter, and that’s why the mirror fogs up more.
But you still have to figure out why it gets that cold in the basement in the summer when the thermostat is set higher. And it’s not just that cold air sinks.
Is your furnace in the basement, and the heating system functioning in such a fashion that the basement bathroom is kept extra warm in the winter; while in summer with the furnace not running the basement reverts to the temperature of the surrounding soil, which never warms up all the way to even the cooled temperature of the aboveground portions of the house?
so the anomaly is that its colder than expected in the basement in the summer…
and not…
that its warmer in the basement then expected in the winter.
Its something about the summer temp that is the cause, not something about the winter temp?
The furnace (and A/C unit which is in the same housing) is indeed in the basement…but it’s not the location of the furnace and A/C that matters.
ETA: However, you’re on the right track about the soil comment.
Yep.
It MIGHT be warmer than expected in the basement in the winter, but not enough to matter. I’ll still get some fogging in the winter, but I can get way more in summer.
Not sure I understand the question, but I’ll say this:
The reason the basement MIGHT be warmer then expected in the winter (though, if it is, it’s not remarkably so) is similar to why it’s colder than expected in the summer.
There are, in fact, two reasons why this is certainly the case in the summer, and likely the case in the winter.
You have an HVAC vent in your bathroom that heats and cools that small room. Your HVAC system isn’t perfectly balanced, so in the summer the vent (might be closest to your HVAC system) sends out an inordinate amount of cooling. If you were able to block the vent into the bathroom you might reduce this phenomena
In the winter its not so noticeable either because hot air rises, or you block the vent in the winter to force air to other places in the house.
Nope.
Assume for this scenario that the HVAC system operates equally through every vent throughout the home and the amount of heating vs cooling out of the system are roughly equal.
Is the inordinate amount of summer cooling due to some other cause, phenomena, machinery, device etc, other than your HVAC system?
Is it due to some other machinery that causes cooling?
Is it due to more cold water running through pipes in your lower level during the summer? (like because you are watering your lawn or filling a swimming pool)
Is the inordinate amount of cooling due to some natural cause and not a human created mechanism?
No.
No.
No.
Both.
One of the reasons the basement gets so cool is a natural phenomenon. The other reason is man-made, though, the man-made reason itself is triggered from natural phenomenon.
ok. Lets try to find out the ‘natural phenomena’ that would cause unusual summer cooling
Is it associated with the temperature stability of the below ground in your area?
Like:
Is there a cave involved? A cistern?
Is there a heat pump involved?
Or just the fact that it is in contact with the earth that your lower level structures are a certain fairly stable cool temperature, and the summer air in the bathroom is warmer than in the winter…such that there is a bigger temp gap in the summer between your bathroom air and walls, than in the winter?
Yes
No to all three.
Yes. That’s close enough to part 1 of the solution.
While not fully below grade, half of the lower level is, and there are only three windows (which being that this is a structure built in 1908 and variously remodeled over the years calling those windows egress is a bit generous but in a pinch you can get out to the street via them), so the lower level is fairly efficient to heat and cool.
No.
There’s still one important piece of the puzzle missing.
is it more humid in your lower level in the summer, so water vapor is more likely to crash out when it hits the cooler mirror.
Less humid in winter would cause less vapor deposition.
Your 1908 house may not be well sealed so the lower level is ‘more damp’ in the summer.
The humidity level is fairly consistent throughout. Assume for this puzzle that all relevant humidity is a result of the steam from the shower.
(Also, not that it matters much for the puzzle, but it’s a condominium in an apartment building, not a house.)
do you have to run the shower hotter in the summer? “Warm” water in winter will feel hot to me, and the same temp water in summer will be chilly. So maybe your crank up your water temp during the summer while showering?
If anything, I run the water slightly colder in the summer, so no.
so, does the question come down to if the earth contact keeps your walls and mirror a fairly stable temperature year round, what makes your bathroom air temperature warmer in the summer than in the winter?
Is that a fair statement?
Or does it boil down to the amount of humidity in the air in the summer vs. winter?
The bathroom temperature is sometimes colder in the summer than it typically is in the winter. (You unintentionally reversed that in your post.)
Even though the thermostat is set higher in the summer (by about 10 degrees) than it is in the winter.
We’ve established that the bathroom being in the basement contributes to this. However, that’s mostly because the basement is by its nature well insulated being mostly below grade and having few windows. However, the basement alone wouldn’t explain it because the basement effect applies both in summer and winter.
So there’s something else at work here. You’re very close to figuring it out. I think the problem is that people are thinking too hard on this.
I’ll give another clue:
Furnaces and A/C units are always pumping out air at the same temperature regardless of thermostat setting. You’re either getting hot air at a constant temp or cold air at a constant temp, and either one is going to be warmer/colder than the ambient.