How do I compare indoor and outdoor relative humidity levels?

In summary, the conversation revolves around the question of whether opening doors will cause a loss of humidity in the house, especially with approaching rainy days. The person notes a decrease in humidity after opening the doors and wonders if it is a significant loss and if humidity flows as fast as heat. They calculate the amount of water per unit volume of air and find that outside air would have a lower relative humidity if brought into the house. The person then looks for information on the exchange of humidity across gradients and is reading about humidity on Wikipedia.
  • #1
needsleep
2
0
If my inside relative humidity level is 50% at 73 F,
and my outside relative humidity level is 97% at 36 F,
how can I tell if I open my door, whether I will lose inside humidity into the atmosphere?

The real life scenario is that my wife complained that the humidity was too low in the house overnight.
I boosted humidity up last night. A LOT.

But then my wife opens both doors this morning upon waking. This is unusual for her. We have several days of rain imminent, as you can see by the above data. My cheap relative humidity dial is showing a slight decrease after 30 minutes of having the inside doors open. The screen doors with their winter coverings of removable glass panels are still in place. A significant heat transfer is occurring through the cracks around the screen doors because of the difference in temperature. But I'm left wondering if my night time humidity is going out the door as well? And is it a significant loss of humidity? Am I losing relative humidity faster than I'm losing heat?? Or maybe humidity doesn't "flow" as fast as heat. I know when it's January in Minnesota, heat flows quite quickly if we open the door!

Thanks,
 
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  • #2
Seems to me you first need to calculate the amount of water per unit volume of air (g/l) for each condition of temperature and RH to arrive at any rational conclusions.
 
  • #3
Thanks for the tip.

I have amount of water per weight of air. I found a calculator online that told me that outside I had 4.67 grams of water per kg of air. And if I were to import this air into my home, I'd be looking at a RH of 27%. That explains why I had a loss of RH in my house. The RH indicator is fairly close to one of the open doors. So the increased humidity overnight was flowing out the door.

I'm curious to know if humidity flows as fast as heat. I'll start by looking for "humidity exchanged across a gradient." I'm currently reading the Wikipedia article on humidity.
 

FAQ: How do I compare indoor and outdoor relative humidity levels?

1. How do I measure indoor and outdoor relative humidity levels?

To measure indoor and outdoor relative humidity levels, you will need a hygrometer or a humidity sensor. These devices can be purchased at most hardware or home improvement stores. Place the device in the desired location and it will display the current relative humidity level.

2. What is considered a comfortable relative humidity level?

The ideal relative humidity level for comfort is between 30% to 50%. This level helps to maintain a balance between too much moisture (which can cause mold and mildew) and too little moisture (which can cause dry skin and respiratory issues).

3. How do I compare indoor and outdoor relative humidity levels?

To compare indoor and outdoor relative humidity levels, simply take the readings from your indoor and outdoor hygrometers and compare them. If the readings are similar, then the relative humidity levels are likely similar as well.

4. Why is it important to compare indoor and outdoor relative humidity levels?

It is important to compare indoor and outdoor relative humidity levels because it can affect the overall comfort and health of your indoor environment. If the outdoor relative humidity level is significantly higher than the indoor level, it can lead to excess moisture and potential mold growth. If the outdoor level is significantly lower, it can cause dry air and potential respiratory issues.

5. How can I adjust indoor humidity levels to match outdoor levels?

To adjust indoor humidity levels to match outdoor levels, you can use a humidifier or dehumidifier. A humidifier can add moisture to the air if the outdoor level is too low, while a dehumidifier can remove excess moisture if the outdoor level is too high. It is important to regularly monitor and adjust these devices to maintain a comfortable and healthy indoor environment.

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