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Comment by goodells | Hacker News Reader

There’s also radon to consider… yikes!

Radon is particularly prevalent in Iowa. A completely closed up house is the worst thing for it!

My dad spent a few years thinking through details about the house before building. Passive radon mitigation was built in (active added later), air exchanger would bring in new air without losing all the heat/cold of the conditioned air, radiant floor heating in the basement, ~24" of blown in insulation in the attic, 6" walls for additional insulation, 24" eves give a bit more shade around the house.

Best treatment of radon is a lot of fresh air exchange. It's what these fans do well.

The fan wouldn’t be exchanging fresh air, it would be drawing it up from the ground. Radon gas is a product of decaying uranium underground. It usually gets into homes due to the “stack effect” where heated indoor air rises (in winter) and draws the gas up through the foundation. The parent commenter seems to be proposing a mechanism to do this in summer as well, just using a fan instead.

You open the windows in the house when running the whole house fan.

When we installed the fan, the documentation mentioned failure to open 9 square feet or more of outside doors/windows could result in a window breaking from the negative pressure.

Like someone else said, you open the windows.

A negative pressure house is bad for more than just radon. It can cause certain appliances to vent bad stuff into the house too.

Would you eventually suck them dry of bad stuff? Would putting appliances in a negative pressure environment before selling them to consumers be good?

"bad stuff" in this case is combustion gas from natural gas appliances, sewer gas from sucking the water out of toilets, etc. So no, there's no end to the "bad stuff" they generate.

Separately, offgassing is an issue for sofas and mattresses, anything made of particle board as well, but if you put them in a low pressure environment, it doesn't drastically accelerate offgassing. If they offgas formaldehyde, they're going to keep doing it after the low pressure period has ended, so better to avoid those materials altogether.

We have a radon meter in the house. Even just a single box fan in Window, sucking air out of the house makes and ENORMOUS difference. We're talking <1 ppm, whereas before it could get up to ~12ppm on bad days. We bought a radon removal system when we bought the house, it it doesn't seem to work nearly as well as simply venting the house.

Yes. First get a sensor so you can track it, radon can change quite a bit over time. I bought two from airthings.com. They support IOS, Android, and even have an graphana plugin (direct, not requiring upload to a cloud first). They track temp, humidity, VOCs, radon, CO2, and something else I can't remember. They have pretty incredible bluetooth range, it's slow, but I can get an update of both sensors from anywhere in my 3 story house. I'm used to bluetooth only sometimes working when on the same floor.

After mapping out my house we saw numbers as high as 15, 4.0 is the recommended mitigation threshold in the USA, 2.6 for the EU.

After talking to a company they recommended sealing our sump pump area, and then installing a fan that sucked air from under our foundation. Our readings dropped from 15 to 0.5, and stayed there. I do wonder how long the sump pump sealant will last, but I have the airthings to watch.

So sure, open up the windows when you can, but I'm glad I can close the windows when it's smokey or cold and still have low radon levels.

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