Thread by @EnergyVanguard

Is humidity control just for warm-humid weather? Or can you grow mold in winter?

A little thread for the part of #energytwitter that hasn't seen the bigger picture of #buildingscience.

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First, if you think you're immune to moisture & mold problems because your climate is dry in summer, let me invite you to take a look inside your fridge. What's inside that container in the back that you've forgotten for a couple of months.

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Extreme example: Family in Kansas had a poorly insulated building enclosure. They kept the inside relative humidity at 50% while outdoor temperature was -5 °F.

Yes, that's ice on the walls & ceiling inside the house. Here are the details:

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bit.ly/3vqD2GT

Another way to create moisture problems, grow mold, & degrade your #indoorairquality is to use unvented space heaters or fireplaces. The mold here is from the high humidity in such a house. They also had water dripping down the storm door when I arrived.

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And yes, keeping unused rooms unheated can lead to moisture, mold, & IAQ problems. To see why, you need to understand the dew point temperature.

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energyvanguard.com/blog/3-importa…

The indoor air is all connected. With the heated part of the house at 70 °F & 40% RH, the dew point temperature is 45 °F. That air gets around the house, even to the unheated rooms.

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Even if you're keeping an unheated room at 60 °F, poor insulation, air leakage, & thermal bridging can make the floor, walls, or ceiling much colder. If the outdoor temperature is 10 °F, parts of an unheated room might drop below the dew point temperature.

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Here's an article on indoor relative humidity in cold weather that explains some of the issues:

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energyvanguard.com/blog/bad-advic…

#Electrification & #heatpumps are great. I've done that in my house & had the gas meter removed.

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But applying energy solutions without considering health, comfort, & durability keeps making Eric Sevareid's quote relevant:

"The chief cause of problems is solutions."

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Whether your ultimate aim is #decarbonization, #comfort, #health, or something else, one rule holds above all others:

A house is a system.

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