Anonymous
Anonymous asked in Science & MathematicsPhysics · 1 month ago

If you leave windows open overnight to lower the indoor temp before hot days, is it best to close them first thing, or once it’s hot outside?

7 Answers

Relevance
  • Vaman
    Lv 7
    1 month ago

    This is what we used to do in the region when the day time temperature used to be 45 C and night it used to 15. We used keep windows and door open during the night time and close it during the day time. It used to remain cool for some time.

    • Commenter avatarLogin to reply the answers
  • Anonymous
    1 month ago

    I close them while it's still cold/cool outside.

    • Anonymous1 month agoReport

      Ideally right before the outside temp starts to increase?

    • Commenter avatarLogin to reply the answers
  • 1 month ago

    The time is when the materials of the walls and contents are at the temperature of the outside.  That time depends on the materials of the house.  Two extremes are a tent.  It reaches the outside temperature quickly during the night.  And a solid brick or stone house where even in the morning the interior stone may still be many degrees above the outside temperature.  So you leave the house open for  lot longer.  It has nothing to do with insulation or other properties.  If there is a temperature differential then HEAT will flow in the direction of that differential.  In all cases.

    So what I do is use a large fan at night to increase the air flow through the house cooling it rapidly then close it meaning it heats slowly.  That way the AVERAGE temperature in the house is substantially less than the average temperature outside even with no other cooling at all.

    • Commenter avatarLogin to reply the answers
  • 1 month ago

    I've been trying to master this for some time.  There are several issues not even related to insulation, such as how many floors does your house have, how much sunlight enters the home, and how much other heat (people, appliances, etc.) is created inside the home.  

    If no one is home, there are no windows, and nothing is running, then closing the windows the moment the outside air temperature rises above the inside temperature is the obvious answer.

    But, if you are cooking, say, and generating significant heat, it is better to leave the windows open.

    Similarly, as the attic heats during the day, it most often makes sense to open the upper floor windows while leaving the lower ones closed.

    If there is a large amount of sunlight entering the home, then you would want to open the windows earlier as well.

    The answer depends on so many variables that you have to find out for yourself.

    • Commenter avatarLogin to reply the answers
  • How do you think about the answers? You can sign in to vote the answer.
  • 1 month ago

    It would be best to close everything before sunrise if you have a very well insulated house with an R value of > 60. This would be a subterranean house. Open it all up when the outside temp falls equal or below the internal temperature.

    • Commenter avatarLogin to reply the answers
  • Dze
    Lv 7
    1 month ago

    i dont think it will make much difference unless you have AC, then running it first thing for alittle while just to remove moisture from the air should keep it feeling nice the furthest into a hot day ...

    • Anonymous1 month agoReport

      It would at least delay the indoor temp increase. Starting from 50 is better than starting from 72.

    • Commenter avatarLogin to reply the answers
  • Anonymous
    1 month ago

    Do you have vents? You don't want the critters invading your house.

    • Commenter avatarLogin to reply the answers
Still have questions? Get your answers by asking now.