It didn't get above mid 80's today with heavy cloud cover. It was high humidity with some rain in the early afternoon. On a day like this, that little 12K BTU window unit will freeze me out in the 384 ft2 room in the new building. I'll bet 5K BTU would have been more than enough today for that one room. One of the 25K BTU window units kept the entire old mobile home cooler than I needed it all day so I'll bet a single 15K BTU would have done fine in the trailer. Too bad there aren't many summer days like this here.