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Window blinds closed or open in winter

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  • Nov 10th, 2021 12:13 pm
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Nov 28, 2016
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Window blinds closed or open in winter

As any home owner, we want to save money on heating/cooling.

Summer time, its easy. Draw the blinds during the day, stop the sun from coming in, helps with ac use.

Doing that however, you dont have to worry about window condensation

Winter its the opposite, open them to let the sun in for free radiant heat in windows that get the sun.

But at night, many sites say to close your blinds to stop heat being drawn towards the windows

Only problem with that is, windows condensation or frost as it gets colder out since there is no air movement from the furnace supply ducts

For those that do this, whats your solution? Do you not close the blinds? Leave them open at the bottom for some air flow? Or just close them and then deal with a frosty window in the morning?

Seems to be varying answers on the internet. Maybe because of the different style of blinds and drapes people can have

These are houses with normal humidty levels to, 30% and under. Ive tried this, and even with humidity in the house down to the mid to low 20's at time, frost still happens no matter what. Eventually it clears up, but the problem is with frost buildup is that it eventually turns back into liquid that then runs down the glass
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Jul 29, 2006
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I have the same issue. The blinds are not really going to do anything to conserve heat in a room at night. The cold is going to hit the blind and fall to the bottom of the blind and roll out. I have venetian blinds so I leave them pulled up a little to let air flow and minimize some of the condensation.

The surefire way to stop this, short of replacing the windows, is to apply the shrink film to the worst windows. I did this in my old condo every winter and that fixed the problem.
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Disagree for summer.

Previous house in Markham ... East facing ... windows all along south side of house ... plenty of light coming in ... therefore no use of lights from sunrise to sunset (9pm). Plenty of airflow with front and rear doors/windows open ... therefore no need for AC.

Current house in Oshawa ... South facing ... have skylight ... plenty of light coming in the house ... therefore no use of lights from sunrise to unset (9pm). Plenty of airflow with front and rear doors/windows open ... therefore no need for AC.

It really depends on the design of your house ...

I only have issues with condensation/frost in late autumn when the temp hovers around 0 to 5 degrees overnight ... ie right now ... once winter hits ... temp stabilizes .. no issues.

Our blinds/curtains are closed at night regardless. Open during the day all seasons. I HATE BEING IN THE DARK. I always like natural light coming into the house.
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jdmfishingonly wrote: Disagree for summer.

Previous house in Markham ... East facing ... windows all along south side of house ... plenty of light coming in ... therefore no use of lights from sunrise to sunset (9pm). Plenty of airflow with front and rear doors/windows open ... therefore no need for AC.

Current house in Oshawa ... South facing ... have skylight ... plenty of light coming in the house ... therefore no use of lights from sunrise to unset (9pm). Plenty of airflow with front and rear doors/windows open ... therefore no need for AC.

It really depends on the design of your house ...

I only have issues with condensation/frost in late autumn when the temp hovers around 0 to 5 degrees overnight ... ie right now ... once winter hits ... temp stabilizes .. no issues.

Our blinds/curtains are closed at night regardless. Open during the day all seasons. I HATE BEING IN THE DARK. I always like natural light coming into the house.
...depends on your comfortable temperature as well. No way in my family we can sleep without A/C during the summer. Airflow doesn't help with reducing temperature.

That being said, I don't open or close my blinds to save energy, I open/close blinds because I want or don't want sunlight. I know this is RFD but seriously, you're not going to be saving that much money assuming you have efficient windows.
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Silver Coins and Numismatics | Heatware
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Dec 4, 2009
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Flamborough
We have California shutters, so I change the direction of tilt, season to season. In summer, I turn them down on towards the window to block as much light. In fall, I tip them down towards the room to allow ambient light in and to direct moving air towards the glass to dry any condensation. Works alright, depending on the rH in the house…
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Nov 21, 2007
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WikkiWikki wrote: ...
Summer time, its easy. Draw the blinds during the day, stop the sun from coming in, helps with ac use.
....
The heat of the sun has already entered the house and residing on the curtain.
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Oct 16, 2008
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WikkiWikki wrote:
Seems to be varying answers on the internet. Maybe because of the different style of blinds and drapes people can have
There are no nee or yee, no right or wrong for this. Each family, each house is different. Houses/rooms face different direction Play around to find your liking..
...
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Jon Lai wrote: ...depends on your comfortable temperature as well. No way in my family we can sleep without A/C during the summer. Airflow doesn't help with reducing temperature.

That being said, I don't open or close my blinds to save energy, I open/close blinds because I want or don't want sunlight. I know this is RFD but seriously, you're not going to be saving that much money assuming you have efficient windows.
Summer ... we have our temp hovering around 21 degrees without AC on ... windows opened ... the odd times we turn on a fan ...

If temps get over 37 outside .... we may turn on the AC (normally if temps rise to 24 inside)

Otherwise the light breeze coming through the house is suffice.
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jdmfishingonly wrote: Summer ... we have our temp hovering around 21 degrees without AC on ... windows opened ... the odd times we turn on a fan ...

If temps get over 37 outside .... we may turn on the AC (normally if temps rise to 24 inside)

Otherwise the light breeze coming through the house is suffice.
That's cool.. what city? My house will be over 24 if the outside temp is more than 30, not 37... I wish that was the case.
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Silver Coins and Numismatics | Heatware
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Windows are cold at night in the winter, so anything that impedes interior airflow past the windows will decrease heat loss. That includes closed blinds and drapes. Yes, that may mean more condensation and even frost on the windows, but that's a sign that you have successfully decreased heat loss. Be sure to wipe away any moisture when you open up blinds or drapes during the day to let sunlight in.

A good passive conservation measure is awnings for south-facing windows. During the summer when the sun is high in the sky, the awning block sunlight and keeps the house cooler. In the winter when the sun is lower on the horizon, the awning doesn't block sunlight.
Last edited by Scote64 on Nov 10th, 2021 10:01 am, edited 1 time in total.
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Jon Lai wrote: That's cool.. what city? My house will be over 24 if the outside temp is more than 30, not 37... I wish that was the case.
Oshawa ... South facing .... nothing blocking the rear of the house ...
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Samwfive wrote: The heat of the sun has already entered the house and residing on the curtain.
Oh please explain this to all of us and how this makes sense?
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congo wrote: I have the same issue. The blinds are not really going to do anything to conserve heat in a room at night. The cold is going to hit the blind and fall to the bottom of the blind and roll out. I have venetian blinds so I leave them pulled up a little to let air flow and minimize some of the condensation.

The surefire way to stop this, short of replacing the windows, is to apply the shrink film to the worst windows. I did this in my old condo every winter and that fixed the problem.
I know at night I tell everyone to leave a gap at the bottom of the blinds for airflow. Some of our blinds we can lower from the top as well, so I have airflow all night.

But sometimes kids dont listen or remember, and then open the blind and the window is entirely frost. But I think this has now been solved now that they are older. Or I open the blind and theres water pooled at the bottom becaue the sun came out and melted the frost.

Window film while would work, probably wont be something I do. They are double pane windows, although buiilder grade, so probably not the best out there.

I wish I could afford to just say, yep, Im goin triple pane. But for most homeowner, spending 20 grand or more on windows at one shot usualy isnt in the cards
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jdmfishingonly wrote: Disagree for summer.

Previous house in Markham ... East facing ... windows all along south side of house ... plenty of light coming in ... therefore no use of lights from sunrise to sunset (9pm). Plenty of airflow with front and rear doors/windows open ... therefore no need for AC.

Current house in Oshawa ... South facing ... have skylight ... plenty of light coming in the house ... therefore no use of lights from sunrise to unset (9pm). Plenty of airflow with front and rear doors/windows open ... therefore no need for AC.

It really depends on the design of your house ...

I only have issues with condensation/frost in late autumn when the temp hovers around 0 to 5 degrees overnight ... ie right now ... once winter hits ... temp stabilizes .. no issues.

Our blinds/curtains are closed at night regardless. Open during the day all seasons. I HATE BEING IN THE DARK. I always like natural light coming into the house.
You can disagree, but doesnt make it right. Becaue your house isnt the same as others across the country.

So you are telling me this would work at +37 degrees outside, with night time lows of +27?

Ive tried it all, and doing that here, and we have roll up screen doors on our front door and deck door, would mean basically +40 degree air being blown into the house. When it cools off at night, I do to cool the house off.

Whats you usual house humidty in the summer for your area with everything open?

I can have my blinds drawn and not need any light either

What do you mean temp stabilizes? In your house, or outside? So when you get to -38 you have no condensation build uo on your windows at all in the corners even. Whats your house humidity? Triple pane windows?

I never close my blinds in the winter during the daytime, excpet when the sun is affecting my eyes sitting at the table, or a sunset that is right in my eyes when Im eating supper.

And only at night at bedtime right now

But thats why I posted the question, since they say closing them at night, which I assume is even when you are still awake, is supposed to help with heat loss, or stop the cold radiating from the window glass, you still have the lack of airflow/condensation issue that comes with thta, because, science
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jdmfishingonly wrote: Oshawa ... South facing .... nothing blocking the rear of the house ...
Prairies, south facing, same as above. Highs in the summer of +39

What are your daytime temp highs? Whats your house temp as well when you do this.

Im sure I could not use my ac to, and sweat my balls off all summer
Last edited by WikkiWikki on Nov 11th, 2021 8:44 am, edited 1 time in total.
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Jon Lai wrote: ...depends on your comfortable temperature as well. No way in my family we can sleep without A/C during the summer. Airflow doesn't help with reducing temperature.

That being said, I don't open or close my blinds to save energy, I open/close blinds because I want or don't want sunlight. I know this is RFD but seriously, you're not going to be saving that much money assuming you have efficient windows.
There is a fine line of saving money, comfort and having what you want.

Myself, I like the blinds open, and we live in a house that has privacy, so people looking in at night isnt an issue. And even if they do, I dont care, its my house

Reason I posted the question was just curious to see how others if they did close them dealt with the condensation build up due to lack of air movement. Cant have ti both ways, one is a direct result of the other

Saying that, shutting my blinds with all our south facing windows, definitely saves on AC use during the heat waves
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teoconca wrote: There are no nee or yee, no right or wrong for this. Each family, each house is different. Houses/rooms face different direction Play around to find your liking..
True, but the science is still the same, close off a window from air flow, condensation will form with the trapped air, and any other air that sneaks in.

I think I do have a system that works, I was just curious to see what others did, or maybe learn something new that would work better
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jdmfishingonly wrote: Summer ... we have our temp hovering around 21 degrees without AC on ... windows opened ... the odd times we turn on a fan ...

If temps get over 37 outside .... we may turn on the AC (normally if temps rise to 24 inside)

Otherwise the light breeze coming through the house is suffice.
Something isnt adding up here. How can a house stay 21 degrees with windows and doors open and outside is hotter than that. Even with a cross breeze, thats just hot air blowing through your house

Temps are 37 outside and you "may" turn the ac on. What magic house do you have?
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Jon Lai wrote: That's cool.. what city? My house will be over 24 if the outside temp is more than 30, not 37... I wish that was the case.
Unfortunately, I need to call bullshit on this. The math and temp differences just do not line up.

Otherwise the ac industry wouldnt be selling ac units, we would just do what this person does
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WikkiWikki wrote: Unfortunately, I need to call bullshit on this. The math and temp differences just do not line up.

Otherwise the ac industry wouldnt be selling ac units, we would just do what this person does
Yup ... you can call it whatever you want. It all depends on the design of the house ... walls, doors, windows, etc.

But if you are so smart ... you would not be posting a question here and then not taking criticism from others.
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