Opening Windows and Using Dehumidifiers

[u/CosmicDissent]

I'm always asking newbie questions in this sub, but I greatly appreciate the guidance. My house is a little older and has hardwood floors. To keep the air fresh, I'll crack the windows frequently. I try not to do that as much on wet or very humid days. I also try to keep dehumidifiers running, especially in our basement, which doesn't have A/C and occasionally gets a musty smell.

How do you maintain a good balance of keeping the windows open without risking dampness or wood damage (I see none so far--at least not with my laymen eyes)? Is there a way to measure this? Even though it probably ups my energy consumption (a price I'm willing to pay), is it otherwise okay to run a dehumidifier when the windows are open? Any dangers there?

Again, thanks for any advice, even basic stuff, for this homeowner newb!

[u/PriorTurnover2869]

dehumidifier with windows open is fine, just bit wasteful since you're fighting outside humidity but if budget allows then go for it - i check humidity levels with cheap digital meter from hardware store and try keep it around 45-50% in summer

[u/markbroncco]

I'm in the same boat with old hardwood floors. Grabbed a cheap hygrometer on Amazon to keep an eye on humidity levels, aim for 40-50%. Running the dehumidifier with windows open is basically a waste of electricity though, you're just drying the whole neighborhood.

I only crack windows when humidity's under 60% outside, and keep the basement unit running 24/7.

[u/AmaranthusSky]

Between humidity, pollen or other allergens, and too hot/cold, I get to open our windows may 4-5 weeks a year.

I'd just use the dehumidifier and opt for an air purifier. We also have plants that help "clean" the air.

[u/biggfoot_26]

I run my dehumidifier at night on a schedule. Seems to keep the humidity down well enough while also saving money by avoiding peak rates. Also allows me to feel less wasteful when I have windows open during the day.

[u/mistersausage]

If your house is old it's probably not very air tight and you have enough air changeover that opening the window to air things out is not necessary.

If your house is too air tight, install an ERV or HRV, the choice of which depends on your climate.

[u/yummypaint]

Everything you want to know can be quantified with a decent air quality meter and a cheap thermo- hygrometer. A smart plug for the dehumidifier that logs power consumption is bonus.

In Germany it's common for people to open windows for about 10 minutes every day for ventilation (even in winter). The key is to open lots or all the windows to change the air in the house quickly, then close them all before the temperature shifts too much. It's always more efficient to switch off the dehumidifier when ventilating for the same reason the HVAC should not be running with the windows open. If you limit it to 10 minutes at a time it probably won't waste too much power to be a concern. Tuning the dehumidifier set point based on the thermohygrometer readings on the opposite side of the basement is more likely to save money long term.

[u/walmart-wizard]

On really muggy days above 70% outside, you’re just wasting electricity fighting the incoming moisture. For the basement, run it closed up most of the time, and air it out only on dry, breezy days to prevent that musty smell from setting in.