catcamper–I emailed Dillon at CLC and he said that they tested the prototype in 40F and below temps and they felt it was warm enough inside, so they decided to forgo the transom insulation to keep the price of the headliner package lower than it otherwise would be. we took ours out last weekend, and it was 50F at night. it was very toasty (had to take off the comforter about 2 am) but in the morning there was condensation everywhere that was not insulated. I will use the Costco interlocking flooring material on the transom, and around the ceiling fan bezel where the supplied headliner does not totally cover. I didn’t notice any condensation on the bottom of the galley flat, nor on the inside of the bulkhead.