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Heated area 200m2 (2,153 sq ft)
KfW 55 standard
Mechanical ventilation with heat recovery
Current outdoor temperature 6°C (43°F)
Heating energy consumption including hot water 35 kWh
Electricity consumption 9 kWh
COP 3.88
I'll start.
Heated area 200m2 (2,153 sq ft)
KfW 55 standard
Mechanical ventilation with heat recovery
Current outdoor temperature 6°C (43°F)
Heating energy consumption including hot water 35 kWh
Electricity consumption 9 kWh
COP 3.88
A
Alessandro28 Jan 2021 08:46I know how cold and warm air behave in relation to moisture ;-)
Warm, humid air is expelled through the window after showering, not cold air entering the room. That’s why I don’t understand your post @halmi.
I keep the window open until the hygrometer in the bathroom stabilizes at the outdoor humidity level. Any further ventilation doesn’t help because otherwise the bathroom cools down too much.
Warm, humid air is expelled through the window after showering, not cold air entering the room. That’s why I don’t understand your post @halmi.
I keep the window open until the hygrometer in the bathroom stabilizes at the outdoor humidity level. Any further ventilation doesn’t help because otherwise the bathroom cools down too much.
Yes, well, Halmi’s explanation is a bit confusing, but I also think that just having windows open doesn’t help much because you don’t achieve enough air exchange in a short time. You need cross-ventilation to let the moist air out and bring in air with less moisture (regardless of whether it’s cold or warm) that can absorb the remaining moisture and then also leave the room.
Otherwise, the moisture just condenses on the open window and stays in liquid form around the window reveal, only to be reabsorbed later by the now cooler air, which can hold less moisture --> higher relative humidity...
Edit: I wrote “pane” earlier, but that’s actually fine because it would be on the outside when the window is closed.
However, all the water in the window reveal and so on is still there.
Otherwise, the moisture just condenses on the open window and stays in liquid form around the window reveal, only to be reabsorbed later by the now cooler air, which can hold less moisture --> higher relative humidity...
Edit: I wrote “pane” earlier, but that’s actually fine because it would be on the outside when the window is closed.
However, all the water in the window reveal and so on is still there.
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Alessandro28 Jan 2021 08:58Well, I don’t quite see it that way.
If you look closely, warm, moist air escapes through the upper part of the window, while cold air enters the room through the lower part.
This creates an air exchange even when the window is open (without cross-ventilation).
The outside humidity level in my bathroom is reached within 5-10 minutes, depending on the outside temperature. The bathroom door is closed during this time!
So, I can’t get the humidity any lower than that.
If you look closely, warm, moist air escapes through the upper part of the window, while cold air enters the room through the lower part.
This creates an air exchange even when the window is open (without cross-ventilation).
The outside humidity level in my bathroom is reached within 5-10 minutes, depending on the outside temperature. The bathroom door is closed during this time!
So, I can’t get the humidity any lower than that.
Alessandro schrieb:
Well, I don't see it that way.
If you look closely, warm, humid air escapes through the upper part of the window, while cold air enters the room through the lower part.
This creates air exchange even when the window is open, but cross-ventilation is not taking place.
Depending on the outdoor temperature, the humidity level in my bathroom reaches its maximum in 5-10 minutes. The bathroom door is closed during this time!
So I can't reduce the moisture any further. 5-10 minutes after showering without cross-ventilation. Then you could leave the window tilted open for half the day.
In our previous apartment, thanks to our private entrance, we would open everything wide (really everything—even in winter) for 10 minutes, three times a day.
And even that wasn’t enough.
You’re right, but the air exchange is too slow. This causes the humidity to simply condense, sometimes even in the bathroom, instead of being removed.
The relative outdoor humidity is measured at a much lower temperature, correct? This means that the absolute amount of water per cubic meter is much lower outside than inside your home (at the same relative humidity level). What halmi means is that cold air contains significantly less moisture overall. When you allow this air into your bathroom, once it warms up again, it can hold more moisture (because it initially contained less moisture). So as soon as you return to your desired temperature, the relative humidity would be lower.
I would just add that this process needs to happen quickly enough so that the moisture doesn’t simply condense on surfaces and remain inside the room. Theoretically, with sufficient air exchange, this wouldn’t matter because the fresh air contains very little absolute moisture. But of course, no one wants to cool down to 5°C (41°F)…
The relative outdoor humidity is measured at a much lower temperature, correct? This means that the absolute amount of water per cubic meter is much lower outside than inside your home (at the same relative humidity level). What halmi means is that cold air contains significantly less moisture overall. When you allow this air into your bathroom, once it warms up again, it can hold more moisture (because it initially contained less moisture). So as soon as you return to your desired temperature, the relative humidity would be lower.
I would just add that this process needs to happen quickly enough so that the moisture doesn’t simply condense on surfaces and remain inside the room. Theoretically, with sufficient air exchange, this wouldn’t matter because the fresh air contains very little absolute moisture. But of course, no one wants to cool down to 5°C (41°F)…
A note on intuitive thinking:
@Alessandro You opened the window for 5–10 minutes. Assuming you actually exchanged the air volume during that time (which is questionable, since you probably aren’t measuring humidity in several spots, right? Maybe there’s still a damp "air pocket" under the ceiling or in a corner.) Then you close the window. But the moisture that has settled on the walls, ceiling, tiles, ceramics, towels, and rugs remains. You won’t get rid of that moisture with 5 minutes of ventilation without cross-ventilation. As a result, you close the window, the slightly cooler air warms up and absorbs moisture again from the surfaces — leading to an increase in humidity.
Is that possible?
@Alessandro You opened the window for 5–10 minutes. Assuming you actually exchanged the air volume during that time (which is questionable, since you probably aren’t measuring humidity in several spots, right? Maybe there’s still a damp "air pocket" under the ceiling or in a corner.) Then you close the window. But the moisture that has settled on the walls, ceiling, tiles, ceramics, towels, and rugs remains. You won’t get rid of that moisture with 5 minutes of ventilation without cross-ventilation. As a result, you close the window, the slightly cooler air warms up and absorbs moisture again from the surfaces — leading to an increase in humidity.
Is that possible?
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