It’s glad to hear the release of LBT 1.5.0! It seems a new bug occured in Honeybee HVAC system of this version. The “All-Air system” and “DOAS system” can’t work well.
Good catch, @YZZhang . People should still be able to assign a HVAC that supports ventilation to a Room without a ventilation specification. I just pushed a fix so that this doesn’t stop the model from being created and the simulation from proceeding: