Sorry, should have said. S/H is Semi-hydroponics as Ryan has said.
It's a growing technique using lecca medium and keeping orchids wetter than you would otherwise expect. Lots of info on this link, and as Ryan said we have a sub-forum dedicated to discussing it.
Semi-hydroponics
The relation to this topic, is that the lecca will noticeably cool as water evaporates from it, there is constant evaporation because it's also constantly wet. That's great when you want to keep a plant cooler than your conditions allow, but not good when your conditions are at the low end of the temperature range your plants like. I have found that in cool temperatures phal roots suffer as a result of this (probably also linked to low humidity due to the heating we do have drying the air, low humidity will increase the evaporation rate and thus cause it to get even colder in the lecca).