I'm in a hothouse!
October 21, 2020 2:14 PM   Subscribe

I've always felt like my apartment was a little on the hot and muggy side, but was chalking it up to me being sensitive to heat - until I got a thermometer and hydrometer and realized it's NOT my imagination. How can I de-moist and de-hot the air?

It is 72 degrees in New York city right now, but it is currently measuring 77 in my bedroom - with a rate of 58% humidity. We have another thermometer/hydrometer in the living room and it's 77 degrees with 56% humidity. And that's WITH both bedroom shades down and the windows open. Something's gotta change.

The specs on my apartment:

* 4th floor (top floor) of a Brooklyn brownstone, building is from 1905.
* Building is brick on the outside, but no exposed brick inside.
* East and West facing windows at either end of the apartment. The bedrooms are on the west end so they get all the sun in the afternoon. The light is one of the things I love about it, but I draw the blinds in the bedroom during the day to cut down on the heat when it's hot.
* One air conditioner in the living room (the other end of the apartment, the one with the east window).

I'm a little reluctant to add a second air conditioner, especially since my roommate would not be able to put one up in HIS room (the one room in his bedroom is also our fire escape). Also, I love having the unobstructed windows in my room. I'd also definitely want to take the AC out of the windows during the winter - they get a little drafty then, and the AC would exacerbate that.
And it's the humidity that is more so of a problem than the heat.

I have Damp Rid things, but I'm not sure they'd be sufficient. Would a compact dehumidifier be better? Or should I spring for a smaller AC after all?
posted by EmpressCallipygos to Home & Garden (26 answers total)
Could this be resolved by adding fans into windows on opposite sides of the apartment - one pulling air in, the other pushing it out? I find air flow to help substantially with both temp and humidity.
posted by NotMyselfRightNow at 2:24 PM on October 21, 2020 [5 favorites]

Exactly. Get two of these fans. There are many months of the year, especially in the evenings, when they will be sufficient, and they use a tiny fraction of the energy of an AC unit, and they can easily be removed from the window. If you don't have one, also get a table/floor fan, which will help to circulate the AC within the apartment when it's really hot and will directly cool you off.
posted by Mr.Know-it-some at 2:27 PM on October 21, 2020 [4 favorites]

Response by poster: Oh, forgot to add that fun bit -

There is a straight shot down a hallway from the living room window to my roommate's bedroom. MY bedroom, however, is a side alley off that hallway and I'm uncertain whether the air would actually be able to make that right turn and flow that way. (Would it?)
posted by EmpressCallipygos at 2:28 PM on October 21, 2020

Can you drink out of a bent straw? As long as there aren't any other major openings - like a door open to the hallway - then the air will flow through the apartment.
posted by Mr.Know-it-some at 2:32 PM on October 21, 2020 [2 favorites]

I would try a fan blowing _out_ in your bedroom, and open windows (or a fan blowing in) elsewhere.
posted by whisk(e)y neat at 2:34 PM on October 21, 2020 [2 favorites]

The mid-west climate in which I grew up was hot and humid in the summer, and our small house had one window-mounted air conditioner. We kept a dehumidifier running 24/7 which helped tremendously. This was a long time ago but it was a small floor model, probably 2'H×2'L×1'W.
posted by davcoo at 2:52 PM on October 21, 2020 [3 favorites]

Without getting into fluid mechanics too deep, yes the air will make a right turn. The overall flow will be less than if it were a straight shot because you have to overcome the air's own inertia which wants to keep it moving straight into your roommate's room, but there will be flow through your room. If you find that there is more air running into your roommates room than yours you can try experimenting with opening and closing your doors to varying degrees to fine tune the flow rates, if you want to get fiddly with it.
posted by dudemanlives at 2:57 PM on October 21, 2020

I mean we can spend all week on optimizing flow (and you should!) but yes fans are 100% the best answer. There are a TON of schemes available. One exhaust one intake is the starting point. Two exhausts may weirdly help, as may two intakes! A big thing will be timing. Especially getting that sweet night air in. You may even end up closing up during the day and circulating/cooling at night. That can be a hassle but it's worth it for a low-cost difference in your indoor afternoon temps, maybe up to 6 degrees F (or more when nights are cool!). Just hang in there and fiddle with fans and you will surely improve the situation. Good luck!
posted by SaltySalticid at 3:17 PM on October 21, 2020 [3 favorites]

As a mild tangent, with respect to your roommate -- for his window, wouldn't a portable AC work? They're less efficient than window-mounted units, but in return they just have a hose running between the unit and the window, so they don't block the "escape-ness" of the window in any meaningful way (this does not mean that a bldg inspector wouldn't wig out, but in a fire you could easily escape through that window).

...not saying you need an AC for this occasion, but if you're going to be there next summer as well it may be something to keep in mind.
posted by aramaic at 3:31 PM on October 21, 2020 [1 favorite]

Since it's a bit cooler outside, why not try opening the windows on warm afternoons instead of closing the shade? Seems likely this is a case of hot air rising, not just solar heating. Also, even if you close your windows overnight, opening them first thing, when it's cooler, and in the evenings, might go a long way to get some air flowing and cool things off.
posted by bluedaisy at 3:57 PM on October 21, 2020

Response by poster: Well, we've had the windows open for several hours now and there is a fan in one window. The temperature has gone down. However, the humidity has gone UP.

I have just priced some compact dehumidifiers and may be springing for one. This is ridiculous.
posted by EmpressCallipygos at 6:18 PM on October 21, 2020

Yes, get a dehumidifier. Possibly two--check the sq ft rating on the one you're getting vs. the space you need it to work. DampRid, even the big jar, won't do much other than keeping clothes in a closet from getting moldy.

I have this portable/compact one in the bedroom of my tiny and not-well-ventilated SF apartment. It's reasonably priced, fits in the tiny space (unlike all of Wirecutter's top picks, which are great but big), and works great. It even has auto-shutoff so there's no danger of a big mess if I forget to empty the tank (because I know me, and I will do that at some point).
posted by rhiannonstone at 6:36 PM on October 21, 2020 [1 favorite]

Get yourself one of those cheap Infra Red point and shoot thermometers. Point it at walls, floors, ceilings, random thing about the apartment and notice the small differences. When it's cooler outside than inside, open the windows and ventilate. When it's coldest outside in the early morning, shut the windows. If you wait until it's warmer above the colder to shut things up then you're loosing the cold air inside so you want to shut things up a bit before they start warming up. Be mindful of the thermal delay in your walls, they heat up during the day and it can take hours for that heat to make it inside after the sun has gone down. On the same concept, they get cold at night and will be cooler on the inside after the outside is starting to get warm. This helps keep that cool air that you've filled your apartment with cool.

Like SaltySalticid said, this is sort of micro-managing things but I can keep my SoCal uninsulated at all and very drafty at that (my windows are slats) about 10-15 degrees cooler than outside without ever turning on the AC (mostly).

Don't know about the humidity thing.

A similar approach also works in the winter, opening up as soon as it's warmer outside than inside and closing up just when it's starting to get cold outside.

Make sure wherever you put the fans that you're not fighting the natural airflow. Go the same direction as whatever breeze you might have it going if it's stable. Blowing out is better than sucking in because at least it's going to take the heat generated by the fan itself outside, and if the fan bursts into flames it's not blowing fire inside.

Seriously there's a long forgotten by me study of industrial ventilation and at least once a failing fan blew sparks inside the building causing fires. Trivia.
posted by zengargoyle at 6:37 PM on October 21, 2020 [1 favorite]

You can't run a dehumidifier and open the windows! You're just blowing the dehumidified air right back outside!

A dehumidifier is just an air conditioner where the hot part is inside. Why would you want to add heat inside when you could cool and dehumidify for the same cost by just using an air conditioner? They only make sense when you don't want to cool or are in such a mild climate the extra heat doesn't matter, neither describe NYC.

If it's 72 degrees outside and 77 inside, you couldn't lower the air temperature even 5 degrees with fans because the walls of your building retain warmth and are warming you and the air back up.

77 degrees isn't that warm -- wear light garments and have the fan blow on you, with or without windows open (if the outside air is cooler than the wall temperature, you should have the windows open). If that's not good enough, air conditioner.
posted by flimflam at 7:39 PM on October 21, 2020 [3 favorites]

Response by poster: So over the past 90 minutes I have watched the temperature in my bedroom drop three degrees - and the humidity RISE from 60% to 64%. I think the humidity is a big part of the discomfort.

I'd prefer to have the windows closed this time of year so I can also have an air purifier going (my allergies are acting up), and the air purifier blows out on the cooler side so I'll be giving that a try. I think the open windows will do me good for the next 2 nights until it gets here.

I'm more gobsmacked that the humidity in here was THAT bad.
posted by EmpressCallipygos at 7:54 PM on October 21, 2020

I have watched the temperature in my bedroom drop three degrees - and the humidity RISE from 60% to 64%.

This is the expected result; relative humidity is temperature related. Hotter air can potentially have more moisture in it so, for the same amount of water vapor in the air, a lower temperature will show a higer relative humidity.

Warm weather in late October is likely to be relatively short lived, so you will soon be into heating degree day territory, but if you can’t survive until things cool off you can either:

1) Move as much outside air as possible through your apartment until inside temperature and humidity approximate outside conditions.
2) Use an air conditioner to cool your apartment and also lower humidity — the secondary function of air conditioners.

If you try to use use a dehumidifier in your situation you will either lose the drier air it exhausts out of the open window, or, if you close the windows, heat up the room further (dehumidifiers blow out air that is both warmer and drier than they take in).
posted by Quinbus Flestrin at 9:48 PM on October 21, 2020 [2 favorites]

And if you've already been running some kind of air conditioner inside a closed air space then yes, opening windows will raise humidity by undoing all the work the aircon's been doing to lower it.
posted by flabdablet at 11:08 PM on October 21, 2020 [1 favorite]

Response by poster: well, moving outside air in until things stabilize is taking too long. I had open windows all night with a fan and the humidity got up to 70% at one point. I am getting a dehumidifier. (And you may take it as read that I know to have closed Windows when I use it.)
posted by EmpressCallipygos at 3:34 AM on October 22, 2020

To give you an idea of what you're fighting against, the National Weather Service has a handy page of hourly temperature/humidity, etc. readings for the last three days. The NY observations are from Central Park, but Brooklyn is not likely to be significantly different.

As of noon 10/22, the temperature and humidity have been fairly stable over the last 24 hours: temperatures steady in the low to mid 60s, humidity fairly steady around 84-97%. It's really humid and muggy/misty out.
posted by Quinbus Flestrin at 9:41 AM on October 22, 2020

Stop looking at the relative humidity and start checking the dew point. The relative humidity is nearly worthless. Right now, the dew point in NYC is 65F which is moderately humid. Higher than 65F is very humid. If the dew point is below 60F, then do the open windows and fan thing. If it's higher than 60F, run the dehumidifier you are considering buying. Getting the dew point down in your house can make 77F temperature seem colder if wind is blowing.
posted by The_Vegetables at 9:49 AM on October 22, 2020 [1 favorite]

If it's higher than 60F, run the dehumidifier you are considering buying.

Or close the windows and run the A/C you have.
posted by The_Vegetables at 9:56 AM on October 22, 2020 [1 favorite]

FYI - many NY buildings were designed to have the window open all winter. Your Old Radiator Is a Pandemic-Fighting Weapon

I wish that I had known this when I had a hot apartment! I had this idea that I shouldn't waste energy by "heating the outdoors". However, if this is how the radiators were designed - then this is how we should use them. I'm planning on using this crazy method this winter to feel safer during the pandemic - fresh air is key to reduce COVID transmission.

When I lived on the top floor of a old walk up with crazy strong radiators that couldn't be adjusted, my method was to open at night with a fan blowing in -30C air. It wasn't enough to let me sleep well, so I send my sympathies!
posted by Gor-ella at 11:15 AM on October 22, 2020

Response by poster: We have some interesting updates - this morning, this has become a bit of a full-on scientific inquiry.

* I have three thermometer/hydrometer units I bought for the apartment recently, and they have been scattered around the house - one in my room, one in the living room, and I gave the third to my roommate to place where he pleased. He put it in his office instead of his bedroom.

* I also have a mini dehumidifier which is definitely working. It is small enough to sit on a tabletop, and I have that on my nightstand; it's been there about 3 days and has been on constantly.

* My roommate brought me coffee this morning in my room - and did a double-take when he noticed the humidity in my room was at 60%. Because it was 50% in the living room, and 47% in his office. And the dehumidifier was sitting NEXT to the hydrometer. He has two theories - either that I'm in my bedroom almost 24/7 these days and it may be picking up on whatever I'm sweating, or the hydrometer in my room is wonky (we literally watched it jump from 60% to 57 and then back again within 5 minutes). He's swapped mine for the one in his room; the one in my room now is climbing, so it's definitely picking up on a rise in humidity.

So - WOULD the presence of a human in a room affect that room's ambient humidity?
posted by EmpressCallipygos at 8:00 AM on October 25, 2020

Yes, absolutely. That's why windscreen demisters are a thing.
posted by flabdablet at 5:50 PM on October 25, 2020

Double-yes. I am famous for fogging up the entire half of the car I occupy, the other half held clear only by dint of vent arrangements.

(Not joking. Friends kick their anti-fog system into high gear when I step into the vehicle, because obviously I'm going to fuck up their windscreen and window visibility.)
posted by aramaic at 6:33 PM on October 25, 2020

Response by poster: We have another explanation - we moved the dehumidifier down to the ground, which also moved it away from the hydrometer. And the hydrometer quickly dropped to about 52%. The dehumidifier is still going, although it has also cooled down and is going to be raining for much of the next several days so this may all be a moot point anyway.
posted by EmpressCallipygos at 8:09 PM on October 25, 2020

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