Abstract. There is a perception that teaching space in universities is a rather scarce resource. However, some studies have revealed that in many institutions it is actually chronically under-used. Often, rooms are occupied only half the time, and even when in use they are often only half full. This is usually measured by the "utilisation" which is defined as the percentage of available 'seat-hours' that are employed. Within real institutions, studies have shown that this utilisation can often take values as low as 20-40%.One consequence of such a low level of utilisation is that space managers are under pressure to make a more efficient use of the available teaching space. However, better management is hampered because there does not appear to be a good understanding within space management (nearterm planning) of why this happens. Nor, a good basis within space planning (long-term planning) of how best to accommodate the expected low utilisations. This motivates our two main goals: (i) To understand the factors that drive down utilisations, (ii) To set up methods to provide better space planning.Here, we provide quantitative evidence that constraints arising from timetabling and location requirements easily have the potential to explain the low utilisations seen in reality. Furthermore, on considering the decision question "Can this given set of courses all be allocated in the available teaching space?" we find that the answer depends on the associated utilisation in a way that exhibits threshold behaviour: There is Contact Author (Authors listed alphabetically.) 2 Towards Improving Utilisation a sharp division between regions in which the answer is "almost always yes" and those of "almost always no". Through analysis and understanding of the space of potential solutions, our work suggests that better use of space within universities will come about through an understanding of the effects of timetabling constraints and when it is statistically likely that it will be possible for a set of courses to be allocated to a particular space. The results presented here provide a firm foundation for university managers to take decisions on how space should be managed and planned for more effectively. Our multi-criteria approach and new methodology together provide new insight into the the interaction between the course timetabling problem and the crucial issue of space planning.