Ok so the RVT location selector just grabs the nearest weather data file and I’ve read that those prefaced with the number 59 contain Typical Meteorological Years, whereas the others are from Autodesk’s “climate server” (source unknown)…so (seeing an actual weather data selector right next to the location tool (head slap)) I switched to the nearest one prefaced with 59 and that just happened to be the same location where I retrieved an EPW for LB. This is the results with RVT numbers revised…
LB RVT
Dec21 182,102 188,079
Mar21 209,450 223,861
Jun21 141,403 155,207
Still off by 3%, 7% and 10% respectively. A lot better than being off by 20% but the path I took to get there is still a bit disturbing…at least the number gradient roughly matches LB.