If I have the dewpoint, relative humidity, absolute humidity, and temperature of outside air, how can I use a template to calculate the humidity of that air at a different temperature if it were to change? Like if that air were to enter a place that’s 65 degrees, what would the relative humidity be with the same absolute humidity at a different temperature?
Have you tried a Google search?
I came up with this in about 10 seconds:
https://www.netweather.tv/forum/topic/85748-relative-humidity-and-temp-change-formula/
It doesn’t give the formula but it links to calculator that does and explains how to use it.
I mean I found calculators but I need to add that functionality to home assistant to make it work autonomously to turn dehumidifiers and humidifiers on, I can’t really use the website and the formulas I found have some exp variable I don’t know what it is and tbh I’m not really well versed in meteorology, I thought someone here might have an idea what to do. But I guess I should probably ask on a meteorologist forum or something. Or a mathematical forum? Look I mean I really didn’t realize how complicated relative humidity and absolute humidity is. I actually emailed some guy that has his email listed on a tool he made that does it via web browser like what you showed me that I thought might be able to send me some links to explain weather and stuff. Idek what vapor pressure is, is that dewpoint?
I’m using this very rough approximation, it works for my needs:
{{(((states('sensor.relative_humidity')| float(default=0)/100)**(1/8)*(112+0.9*(states('sensor.temperature')| float(default=0))) )+(0.1*(states('sensor.temperature')| float(default=0)))-112) | round(1, 0)}}
Would mold indicator cover your needs? I use it to control ventilation to keep humidity below the point where mold could grow at the coldest spot in my house.
You can use this HACS Integration: GitHub - dolezsa/thermal_comfort: Thermal Comfort sensor for HA (absolute humidity, heat index, dew point, thermal perception)
Why don’t you make it easy and buy a cheap zigbee temp and humidity sensor?
Then you won’t have to guess by trying to calculate it.
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… I have a temperature and humidity sensor both inside and outside… I need to find out what the relative humidity of the air outside is when it enters my house, because it’s a different temperature. Air at 35 degrees at 40 percent humidity is only like 20 or 30 percent relative humidity at 65 degrees because as air heats up it can absorb more water before condensing. Therefore of I want my chinchilla to be not dead I need to make sure that I’m not turning on the dehumidifier if the humidity outside is too low when it changes to a warmer environment and the same is true in the summer when it’s 80 degrees out because the humidity outside at 40 percent when it’s 80 degrees is probably like 60 percent of the total capacity of the air, or 60 percent relative humidity when it comes inside so I need to ensure the humidifier doesn’t erroneously come on. I have the inside and outside temperature, relative humidity, absolute humidity, and dewpoint. How do I determine the outside humidity when moving to a different temperature is the question. Not how to guess the outside humidity with the inside humidity, that’s unnecessary.
Yes I have that. How do I use it to the the outside relative humidity and temperature to find out what the humidity relative to the inside temperature would be if the air moves inside?
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Can you explain what this is doing I’m not sure i quite understand.
What does this do? Does it provide the relative humidity of the air outside if it were to change temperature to the temperature of inside?
Then I must be missing something.
Whatever the relative humidity outside is is irrelevant since whatever it is outside when it moves inside will be whatever the inside humidity sensor will read.
All you need to do is just look at the reading of the actual humidity inside from the inside sensor.
why do you need to calculate it if you already have a sensor telling you what it actually is?
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Jesus tapdancing Christ… no. If the humidity is 40 percent outside and it’s 30 degrees when it moves inside it will be around 20 or 30 percent humidity, even if my indoor humidity is at that moment 45 percent. The humidity changes with temperature. And if outside air is constantly coming in, which it is because my house is not hermetically sealed like a Tuna can, it will constantly drift towards the outside humidity as it really is at the indoor temperature. Meaning if I turn on a humidifier and it goes slightly over the max allowed setting I don’t wat the dehumidifier kicking on if it’s not humid outside, which I need to calculate, because if it says it’s 40 percent humidity outside, that’s not the humidity inside. Humidity is relative. It’s called relative humidity. I need to find the relative humidity of the outside when it changes to the indoor temperature to prevent my humidifier and dehumidifier ping ponging on and off repeatedly by using what the actual relative humidity of outside is when it’s at the indoor temperature, which I’m trying to figure out how to calculate. You entirely misunderstand what I’m talking about sir and I’m really not sure how else I can explain this.
I didn’t tag you because I forgot.
Well, it calculates the dewpoint from outside temperature and humidity, which I’m pretty sure is the answer to your initial question - but as you edited your opening post and you’re now asking something completely different, it’s pretty irrelevant right now :).
Dude what ru Talking about? I have all that information from thermal comfort. This is my first post
If I have the dewpoint, relative humidity, absolute humidity, and temperature of outside air, how can I use a template to calculate the humidity of that air at a different temperature if it were to change? Like if that air were to enter a place that’s 65 degrees, what would the relative humidity be with the same absolute humidity at a different temperature?
That’s what I’ve been asking all along. I’m sorry you didn’t read my post properly but you can’t blame me for your misreading my post and honestly this is getting silly. I don’t know how many times I can explain it and I don’t think I edited the first post unless their was a typo.
Forgot to tag u
I believe this may end up being a very complicated calculation.
Here is an interactive Psychometric Chart that may help you create the calculations needed.
Well, sir…
You seem to be under the impression that the air outside only moves to the inside in big chunks. Almost like if your house was hermetically sealed like a tuna can and then you suddenly opened said tuna can. If that was the case then you might have a point.
But it doesn’t work like that. Air is continuously infiltrating into (and out of) your house and as such the humidity outside and humidity inside are constantly in flux trying to reach an equilibrium.
But the humidity inside can’t change instantaneously even if the humidity outside does (which that never does either). It takes time for the humid air (either higher or lower) to move into your house. And during that time it’s mixing with the air already in your house and being brought to the temperature inside your house so its always continuously changing.
But it will always be at whatever the sensor says it is right now.
And if you think you can use a simple equation to try to anticipate what the humidity will do in the future inside your house based on outside conditions then you won’t be happy because there are so many variables - rate of change of outside air temp, outside air humidity, inside air temp, inside humidity, if the air conditioner is running (pulls moisture out of the air), gas stove running (puts moisture into the air), if you are taking a shower, doing dishes, laundry, how sealed your house is so you know what the air exchange rate is (meaning how much is going in vs going out and how fast), etc., etc.,… hopefully you see my point.
The best you can do is to see what the actual humidity is right now (yes, relative humidity) and use that to control your humidification/dehumidification devices. If you are concerned about overlap then you need to set the hysteresis in both devices automations so it won’t happen.
And one more thing is that you might have a misconception about the term “relative humidity”.
It’s not relative between the inside and outside.
It’s relative to how much moisture the air actually contains (either inside or outside) relative to how much moisture the air can hold at a given temperature for a given air volume.
It is relative to temperature, and dewpoint and other environmental conditions.
If the humidity of the outside air is greater, overall in moisture content, I need to ensure the humidifier does not turn on because the outside air will slowly filter in and change the humidity to become higher.
If the outside relative humidity is 40 percent, and inside relative humidity is 40 percent, but the outside temperature is 95 degrees and the inside temperature is 65 degrees, if the air outside were suddenly cooled to 65 degrees, it would be extremely humid relative to the indoor temperature. It would no longer be 40 percent humidity, it would be much much higher,
If i used the outside relative humidity to determine if the dehumidifier should turn on it would still turn on if it was set to 43 percent humidity. However over time the humidity would continue to increase as the absolute humidity outside is extremely high compared to the inside humidity.
As you can see from the photograph attached
You can see the absolute humidity outside is 2.77g per meter cubed and Inside the absolute humidity is 5.78g per meter cubed, this is despite the fact that the inside RELATIVE humidity is actually LOWER. at 5.78g per meter cubed the humidity is 35 percent at 66.7 degrees
The absolute humidity outside is 2.77g per meter cubed and a higher relative humidity at 37% relative humidity.
So to recap, it’s less humid outside in how much total water there is in the air by volume. But the relative humidity is greater.
Keep in mind my humidifier has been on and off to keep it at this humidity. If not it would be 2.77g per meter and even Lower than 35 percent.
So to recap, (please read and understand what I said before commenting because you keep misunderstanding me)
The relative humidity is a number that depends on the temperature and dewpoint and absolute humidity.
HAVING MORE WATER IN THE AIR DOES NOT MEAN THAT THE RELATIVE HUMIDITY IS HIGHER UNLESS THE TEMPERATURE IS LOW ENOUGH THAT THE AIR CANNOT HOLD AS MUCH WATER. PLEASE DO NOT COMMENT IF YOU CANNOT UNDERSTAND WHAT I AM SAYING BECAUSE IVE EXPLANED THIS REPEATEDLY AND YOU HAVE CLEARLY NOT READ WHAT I HAVE EXPLAINED.
IF THE RELATIVE HUMIDITY OUTSIDE IS 35 PERCENT, AND IT IS COLDER THAN INSIDE, IT WILL BE A LOWER RELATIVE HUMIDITY WHEN THAT AIR ENTERS MY HOUSE.
I AM TRYING TO CALCULATE THE RELATIVE HUMIDITY OF AIR UPON ENTERING MY HOUSE. IT IS NOT THE SAME AS THE RELATIVE HUMIDITY OUTSIDE BECAUSE OR THE DIFFERENCE IN TEMPERATURE. IF YOU STILL DONT UNDERSTAND WHAT I MEAN PLEASE STOP COMMENTING BECAUSE I’M JUST GOING TO PASTE THIS AS A RESPONSE. IM NOT EXPLAINING IT AGAIN.