Fatparrot,
You are on the fortunate side of all the environmental choices. I was likely the poster you are referring to. Having lived with high humidity previously and now residing in the high desert of Idaho I can attest to the benfits of low humidity. Remember that the outside conditions have very little to do with what is occuring inside your home. Showering, washing clothes, watering plants, breathing, cooking, etc. all contribute to adding humidity to your somewhat sealed environment. As an example, right now the relative humidity as reported by the weather service where I live is 20%. I have 50% relative humidity inside my home without any humidifier.
If you live in a very dry place and it's hot outside and running your homes A/C, the air that passes through the cooling coils is dry enough to not cause much condesation, so humidity is not taken out of the air. But, by lowering the air temp, the relative humidity rises. That's where the word "relative" comes from in the term relative humidity. It is relative to the air temperature. That being said, if you still have very low humidity in the winter and are heating your home, the reverse happens and the inside relative humidity is less than outside. THAT is when you will need humidification. Simply buy a gauge and monitor what's going on inside your house and you will understand. If you remember my caution about removing too much humidity the same caution applies to adding too much. If your home has high humidity and the outside humidity is low, vapor pressure will make the humidity attempt to equalize itself with the outside conditions. Too much water vapor going through your walls will damage the materials contained therein.
The point is to not go overboard with whatever corrective measures you take. Also, if you ever install a humidifier in your heating system I advise getting a water softener first. Most residential humidifiers drip or spray water on a pad (or screen) that is placed in the path of the heated air. The water evaporates and raises the humidity. If you have hard water the humidifier will malfunction within a couple of years from mineral buildup. The worst case would be too much water being evaporated (it's a complicated thing to describe but imagine a faucet that won't shut off) and raising the inside humidity to a point where you get condensation in places that will damage your home.
After this long and perhaps confusing post, my guess is you need to do absolutely nothing. That is the case in my home. In any case, monitoring the humidity is a good thing.
