窗户上的温度，相对湿度，露点和凝结
Hi,
A quick background to give you context. The 1867 sq. ft. (basement included) semi detach house was built in 2009 as part of a new large subdivision by a big developer in the west end of Ottawa. The house is a basic 2×6 wood frame, R-20 bat insulation, vinyl siding, natural gas furnace, no HRV and solid wood exterior doors. We keep the house temperature at 15°C (60°F) at night and during the day it’s at 20°C (68°F).
自第一个冬天以来，我们就一直在窗户上看到水分积聚，但建筑商只是说这是由于新建筑而导致的水分。在我们搬进去之前，我们购买了一个独立的除湿机，该除湿机在地下室的起居区将近一年，并将其设定为45％。
在淋浴后15-30分钟，我们在浴室里的风扇在浴室里运行，并且在大部分时间做饭时，引擎盖风扇正在运行。当天气约为0°C（32°F）时，我经常打开门/窗户以播放房屋3-5分钟，但由于我们的加拿大冬季，这可能只会每月一次一次。
今年，我决定摆脱我在房子里的一些植物，只给他们每两周的一小部分水。当天气在-1°C和-12°C（32°F - 10°F）之间时，这似乎有助于减少窗户底部的水分量。厨房岛上的湿度计约为30％，自圣诞节以来，地下室的除湿机在低30％的情况下显示出来。
2020年2月9日,周日我们有一个非常寒流come though the Ottawa Canada area and at around 8:00am the temperature at -25°C (-13°F) and feeling like -31°C (-24°F). When we get cold weather around -20°C or colder, there will be ice forming on just about all of the windows.
After leaving in the house for ten years and reading a ridiculous amount on the subject, I believe on have narrowed it down to two issues; no HRV/ERV and cheap windows with low U-factor.
Anyone else have any thought?
Thank you,
阿诺德
GBA Detail Library
由气候和房屋部分组织的一千个建筑细节的集合
答复
That's common when it gets that cold, especially with builder grade windows.
在68 F内部和35％的RH露点为40 F，温度需要在表面上方的窗户上方，因此，当它真正的寒冷时，您就会变得霜冻。如果您厌倦了擦拭窗台，请增加内部温度和降低湿度以对抗它。
Google "dew point" and "windows" and you'll get some reading.
I would be more concerned with a dehumidifier running nonstop to keep it at 45% well after year one.
谢谢卡尔森的回复。我应该澄清一下，我的脱氧仪单元并没有始终脱落。当我的设备上电动机时，风扇不停地运行，而冷凝器只有在湿度下降到我所设置的湿度时才会触发，该湿度通常约为45％。
My builder grade windows are barre minimum the code require when it was built and I suspect they are at around an U-factor of 0.5 (R-2) but apparently they are Low-E.
我想每当温度低于双数摄氏摄氏度时，我都会继续擦拭。
Thanks,
阿诺德
I have rather expensive triple pane windows, and I still end up doing moisture of the windows at -20c. It probably buys be a little bit more leniency, but eventually you'll get condensation.
Hi,
I thought I would give an update for everyone else reading this thread in the future. In the spring I bought a new hygrometer on amazon which indicated to me that the other one I had was way off. A few day ago we bought a new dehumidifier (Frigidaire FFAD5033W1) after our ten year old one keep icing up and not really removing much moisture. In two days we been running it the relative humidity leave in the house went from 50-55% to the low 40%.
This morning the outdoor temperature was -15*C (5*F) and hardly any condensation on our windows. I suspect the old dehumidifier was not very effective at removing moisture, especially in the last year.
Thank you,
阿诺德
You should find that a HRV in the Winter is a less expensive way to reduce humidity than a dehumidifier.
+1 !!!
A dehumidifier converts the moisture to sensible heat (temperature), but at a relatively poor coefficient of performance when the dew point of the indoor air is <10C (where it has to be to mitigate window condensation). The HRV/ERV solution is more efficient, and the slight heat loss from that ventilation rate is made up by a (hopefully) more efficient heating system.
嗨，阿诺德，
这是一个兔子洞，您可以下降：Understanding Dew Point。而且，就达娜（Dana）而言，如果您开始将HRVS/ERV的效率视为未来的解决方案，那么Martin Holladay的这篇文章将列出每个解决方案的差异和最佳应用：HRV还是ERV？。
I agree an HRV would be better solution but given the cost to have one installed when we will be starting our new house build in 2021, it wasn't worth it. We're going to be putting that HRV money towards the new house.
Thank you,
阿诺德
Dew point is defined as saturation vapor density or 100% relative humidity. Dew point is the transition temperature between evaporation and condensation. Condensation occurs on windows because the temperature of the glass is below the dew point temperature of the air. '
露点温度完全基于空气中的水分量，并且不受空气温度的影响。可以使用空气温度，相对湿度和适当的图表找到露点温度。当然还有一个可用的公式，但我建议一个比较图表...相信我！
为了阻止凝结在窗户表面上形成：您必须：
（a）将空气的露点温度降低至窗户表面温度以下的水平
（b）将窗户表面温暖到空气露点温度以上的温度
（c）两者的组合
Relative humidity can be raised or lowered simply by adjusting room temperature. This change may make a person feel more comfortable, but changing temperature does not affect dew point. Lowering Rh by raising temperature MAY affect condensation on windows IF it also raises glass temperature above the dew point level. If the windows aren't sufficiently warmed by increasing room temperature then it will not affect window condensation.
就像更换室温一样，升高或降低空气的水分水平也会改变空间中的相对湿度，但是与温度变化不同，水分水平的变化也会提高或降低露点，这可能会影响窗户冷凝的潜力。向合唱团讲道，但这就是为什么除湿机，ERV/HRV工作并提高温度“干燥空气”的原因。
快速温度变化公司的例子ntrol humidity:
考虑在65°F的房屋，相对湿度为40％。在这种情况下，房屋中有6.25克的水，等于38°F的露点温度。如果窗玻璃小于38°F，则很有可能有水分，甚至可能在玻璃上积聚。
Clearly the Rh is too high, so we raise the air temp to 75°F and we have lowered the Rh to 29%, which most people would consider to be very dry no matter how you measure it. With the result that the windows still have condensation build up because despite the lower Rh, we have done nothing to lower the dew point. It's still at 38°.
Whole point being, be careful when talking about Rh and window condensation, it can be tricky and is often misunderstood.