Consider when you’re outdoors and it’s 35C… a dew point of 23 or even 25C will feel very nice.
Likewise, mold responds to relative humidity, not absolute humidity.
Absolute humidity is a useful metric where you have an imperfect boundary between air at different conditions, such as ventilation, infiltration and vapor drive.
]]>I think that RH doesn’t tell us how comfortable we live indoor. The RH is as the name said “relative” and show us a percentage of water vapor in a mass of air reported to the max amount of water vapour that mass could contain. It doesn’t tell us the amount gr/m3 or gr/kg in the air. We could have at different temperatures different RH. Isn’t it? As we heat up the air the RH will decrease. But the Quantity of moisture gr/ m3 remain the same. The absolute quantity of moisture will tell us the real absolute quantity of moisture into the air, that is Dew Point an not RH. Leet say in a summer morning we have outside 21C and RH 100% and DP 21C. It means that the air is saturated and we will see dew on the grass. During the day the air will worm up to 32C and RH 50% at the same DP of 21C. During the day even if we have the fantastic 50% RH as everybody tells is the optimum. At DP of 21C the air is very humid. The comfortable limits is between 10-15C DP. Am I right? In this case presented we have to humidify, ventilate etc our house according to DP and not RH.
]]>@Alejandro, in addition to
@Alejandro, in addition to what Allison said, an ERV can in some cases RAISE RH in winter, if used as primary exhaust for a high use shower. This is most likely to occur during shoulder months when weather can oscillate between periods of rain mild temperatures and cold snaps.
In warm climates, ERV’s are most useful for reducing ventilation-induced moisture in summer.
]]>Interesting that you are getting northern lights at 35%, generally as recall it shouldn’t be happening until you are in the teens to maybe low 20’s
As for when living down south, I might say 30 to 40.
]]>Gerald, I’m surprised you don
Gerald, I’m surprised you don’t get static electricity at 25% RH. I get it at about 35% in my condo. Regarding your question about whether you should get a humidifier, I’d say if it ain’t broke, don’t break it. If you’re comfortable and don’t notice a static electricity or dry skin problem, why rock the boat?
The ideal summer humidity is a different animal. Up to 60% is fine then. If you’re getting 50%, that’s great.
]]>Good questions, Nate. Most
Good questions, Nate. Most people keep their homes around 70° F, and that’s what I assumed here. For those who keep it significantly cooler indoors, the chances of accidental dehumidification are greater because the surfaces are cooler.
In summer, a dew point of 55° F is what you get at 75° F and 50% RH. In winter, you get 45° F with indoor conditions of 70° F and 40% RH.
]]>What temp are you assuming for RH again? Would dew point be good to add as well?
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