Yep! Surface mould is almost always caused by poor ventilation especially in old solid walled buildings where the warm moist air hits the cold surface of the walls and condensates. Try to maintain an ambient temperature, fit controllable trickle vents to windows (if there are any) try not to put furniture against external walls.
Air conditioning is an option which obviously has running costs; http://www.passivent.com/intelligent-mechanical-extract-ventilation-imev/p/4
or a passive vent system like this will help which uses no electricity; http://www.passivent.com/cross-flow-and-passive-