How will I dry herbs?

In between raven calls, which always make me stop and observe, I was walking around the plantings, weeds, and wild things.  I've noticed a number of medicinal herbs which are ready for harvest -- Red clover (trifolium pratense) and American plantain (plantago rugelii).  I've cleaned out a small, mostly enclosed stall in the barn which will hold a home made herb drying rack.

Looking at that room I can think big -- seal the outside, insulate, build a raised floor, and finish the inside to house shelves and a climate control system.  Or, I can think of it as a secure room to hold an enclosed herb drying rack that I build.

Keeping true to my vision to keep it simple, I will do the latter -- use the room close to as-is.  It will keep water and animals out, has electricity, and a new roof I put on last year.  The only improvement it needs besides cleaning it out, is a heavy piece of plastic laid on the floor to act as a vapor barrier to keep the soil moisture out.

Here's how it looks, ready for the herb drying rack

(The insulated box holds some solar electric charging equipment)