Now that the temperature outside has dropped, the windows start to accumulate water vapor. I am assuming that it might also lead to that black stuff forming. Is there a more efficient way of dealing with the condensate than wiping it dry every day?
Now that the temperature outside has dropped, the windows start to accumulate water vapor. I am assuming that it might also lead to that black stuff forming. Is there a more efficient way of dealing with the condensate than wiping it dry every day?
Please measure the room temperature, humidity in the room as well as the temperatures of the frame, the surrounding walls and the glass. A simple IR thermometer and a cheap digital hygrometer suffice, stick some matte tape to the glass to measure that. Find out, what the dew point is and how far below that the critical surfaces are.
As a reference: I currently have 23°C room temp, 40% rel humidity, the walls are at about 22°C and the window frames here show at 19°C. No condensation, because the dew point is well below all of that.
Thank you for the suggestion. My hygrometer shows 65% at about 20C. But the humidity outside right now is like 90% with all the snow and rain. So I guess part of the problem might be that the room is too cold.
See the thing is, humidity is always given relative to the Dew Point in percent. If I assume 0°C for outside with 90% humidity thats 4.6 g/m3 of water. In your room with 20°C and 65% humidity its 11.2347 g/m3
So if you open your windows your humidity will decrease. Warmer air can store more water.
Under ideal conditions you could get to 27% at 20°C which you will never reach, but opening the windows for 5 minutes (ideally two windows on opposing sides of the house to get a good draft) should get you below 55% already. Repeat it three time a day and you will stay below 50% humidity.
Also, thanks for the detailed calculations. I never realized how that actually worked
Glad to help :)
I forgot to mention: Thats also why you get condensation on windows. The window is cold and cools the air near it. The air than can hold less humidity and it condensates on the window.
If you measure the temperature of the coldest spots on your windows you could even calculate how much humidity you can have in you flat at 20°C before water condensates there.
I’m kind of shuddering at the thought of opening my windows in this cold, but ok, I’ll try that)
There’s fan systems that take outside air and inside air and pass them by each other in a heat exchanger. I’ve got a few of those in my house, the UI looks like this and this explains the principle quite well I think:
Maybe your landlord is open to the idea to install one of these. You get permanently fresh air without losing too much heat, they get some peace of mind that there’ll be no mold in their property.
Thank you for the tip! Our windows do have two “ventilation things” on each side that move air in and out. I am assuming they kind of do what the picture shows.
Eh, not too likely if they go directly into the wall. The trick with the one I’ve mentioned above is the heat exchanger. The warm air from inside passes its heat to the cold air from outside without touching it directly. The water it loses during that runs to the outside pipe and drips off.
Ah, ok. The ones we have are embedded into the walls. I had a feeling they were just a gimmick)
Not the room, but certainly some surfaces. at 65%/20°C the dew point is at about 13°C. Any surface near or below that temperature will collect water droplets. Find those, measure them and then either find a way to get these surfaces warmer or lower the humidity in your room until they are no longer beneath the dew point. If necessary, get an electric dehumidifier. Unless you need to run it all the time, it’s a valid workaround for a few days per year.
Just checked the windows temperatures. Interestingly, the temperature varies quite a bit along the surface of the window. The middle of the window is about 18C but the bottom measures at about 13C, which is exactly the dew point for my 20C / 65% (thanks for the calculator, btw).
Thanks so much for a detailed answer, I will try to follow your advice.