Window condensation / sweats

[scottieyoon]

I live in less than a year old house with the latest energy efficient windows. This is my first winter at this house. I see lots of water/moisture around window, top to bottom, where they are literally dripping to floor. I check other postings. I don't see any visible leak (or at least I don't feel it). My wall clock which has humidity level check is telling me it's at 30, so I think that's pretty low. I'm keeping the house at 70 degrees and currently here at North Texas the outside temperature is at above freezing (around 35??). All my windows are like these. What can I do to get rid of this problem? I'm contacting the home builder in mean time.

[Joseph Meehan]

What kind of frames do the windows have? Metal?

At 30% humidity you should not be having much if any condensation on a good thermo window unless the frames are a problem.

[Don Phillipson]

First, buy a reliable humidity meter. The component in your wall clock is probably malfunctioning.

Secondly "the latest energy efficient windows" suggests your new house is probably more airtight than you were formerly used to.

Condensation occurs on a surface (e.g. window glass) when it is cooler than the "dew point," the temperature at which dissolved H2O vapor in the air turns to visible liquid water. This can easily happen when it is freezing outside and you have single-pane windows. Double glazing reduces the likelihood of interior condensation but it can still happen, depending on actual temperatures and humidities. You may feel the benefit of a dehumidifier (but not if your actual humidity were truly 30 per cent.)

[avid_hiker]

Is this on one window or all of them?...........how many are sweating? Do you raise or lower the inside temp when you leave the home? Then raise/lower the temp when you again arrive home, etc? Do you also have storm windows on the outside of these windows?

Me...live in New England and always have this problem. After shutting storm windows......no more problem.

[terry]

We had an almost identical posting string to this recently. In which someone wondered whether to blame the condensation on their new window. Sounds like high humidity in a well sealed house. Ventilate and/or air exchange!

[scottieyoon]

All my windows are having the same problem, upstairs and downstairs, some more than others. We keep the house at the same temp all day. No such thing as storm windows, just dual layer with tiny gap between (no air, someone told me) and it is slightly tinted blue per new city code for hot summer here in Texas. The frames are aluminum and water is on there, too. I'm gonna try getting reliable humidity meter and then try de-humidifier. I think the reading is wrong, too. I also read that on new house, the new lumber and concrete will generate more moisture than, say old house. I asked my wife to do the followings meanwhile.

open blinds for better circulation. circulate air from outside for an hour or so. keep the fans running at "on" instead of "auto". and keep mopping .....

[jolt]

At 70 degree indoor temp. at 30% RH the window temperature would have to reach 28 degrees or less for the moisture in the air to reach dew point. With a accurate indoor temperature and RH reading you can determine the temperature the glass must reach for moisture to condensate on the glass.

If the outdoor temperature dropped suffiently over night water droplets on the glass could occur.

You might try if you have a humidifier turning it down, or if several long showers are taken in the home each day, use the venting fan while taking a shower. Also sometimes after boiling something like pasta this will happen no matter what else you do if the home is very tight. If it is constant problem it maybe worth monitoring the RH by purchasing a hygrometer or sling psychrometer.

[scottieyoon]

My home builder just replied back with a PDF to read. I found the exact content in web.

[nicksanspam]

No. Tdp = (70+460)/(1-(460+70)ln(0.3)/9621)-460 = 37 F...

20 TI=70'indoor temp (F) 30 TA=35'outdoor temp (F) 40 RIF=.67'R-value of indoor air film 50 FOR RV=1 TO 4'window R-value (ft^2-F-h/Btu) 60 TG=TI-RIF*(TI-TA)/RV'glazing and dew point temp (F) 70 RH=100*EXP(9621/(TI+460)-9621/(TG+460)) 80 PRINT RV,TG,RH 90 NEXT RV

Window glazing Max Relative R-value temp (F) Humidity (%)

1 46.55 43.15557 2 58.275 66.32038 3 62.18334 76.20583 4 64.1375 81.62463

Nick

[scottieyoon]

I haven't seen code like that since high school. Is that BASIC?

[nicksanspam]

Yup. Just like the code in the ASHRAE 55-2004 comfort standard :-)

Nick

[Joseph Meehan]

Sorry to hear that. It is nearly certain that the problem is the frames. Aluminum is a terrible material for frames. It happens to be a great conductor. It is so good it is even draining the heat from the edges of the window on the inside which is why they are also sweating.

Some aluminum frames have thermo brakes built in, but it sounds like yours don't.

Sorry, but the only fix I know is to replace the windows.

[bowgus]

For the 1st year, there will be excess humidity in the building materials in the new house ... it'll likely calm down about in the 2nd year ... that was my experience. In the meantime, if you don't have power ventilation, you'll have to make do somehow ... crack a window open maybe. In my case, the new house attached to the old house, so I put an opening at the top of the adjoining wall letting that excess humidity go into the dry, leaky old house next door ... an excellent solution :-)

[Joseph Meehan]

Let me add one thing. Sometimes you can have luck by allowing additional air circulation to the windows. Open any curtains or drapes and maybe even use a fan to move the air around. Try that for a couple of hours and see if it helps.

[scottieyoon]

Replace all windows?? I don't know how to convey that message to my builder. All our subdivision homes (200+) will have to do the same. I said aluminum but that's my best guess. They are metal for sure and very thin. I can push them and bend them a little. I don't think I can bend steel by my finger. Moisture is building at the frame, too. I'm sure these are massively produced windows, probably well known brand due to high efficiency rating.

[avid_hiker]

That is a very informative article. Very interesting. I shall keep that in mind for my home also.

[avid_hiker]

was wondering if possibly you had a drippy water pipe somewhere causing this excess humidity. Do all your neighbors have the same problem?

[scottieyoon]

In fact, I was going to ask a neighbor this week. We are all here for the first winter.

[scottieyoon]

About this energy efficient windows. I have to say that these windows really work during summer. I had 2500 sq ft house just 2 miles south from where I'm at and my electricity bill was about $300 per month. Now with 4000 sq ft house with these windows, I'm still at $300 per month, max !!! My old house was built in 1999. I'm sure other factors helped, like SEER 14 AC (two of them), which I paid extra for. And these blue tint actually looks pretty good. Sorry, off the subject.

[Abby Normal]

There is a lot of moisture of construction in a new home, and a lot of the energy efficiency windows may have what can appear to be high R-values, but this tends to be for the centre of the glass. The frames can short circuit a lot of heat and sometimes they may have metal spacers separating the panes of glass. Metal frames would be just asking for it.

U-shaped condensation patterns are common as the windows are a lot colder around the edges than in the middle of the glass.

New homes can be fairly air tight, and in the winter the people can become their own humdifiers, but this is more common in the North.

You may have to ventilate a lot during this first winter. Hopefully you have bathroom fans vented to the outside. As an experiment try cracking open one window and running a bathroom fan steady to see if the dry air can drop your RH enough to stop the condensation.

Getting the glass warmer will help too. Try keeping the drapes open at night, this keeps the windows a little warmer. Bay windows are always the most prone to the condensation.

If running a fan during the cold weather does not lower the RH, maybe check that you are not creating the moisture yourself. Lots of plants being watered, simmering foods for a long time, hang drying clothes inside the house etc.